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Tuesday, 24 November 2020

Introduction to Nanoelectronics

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Introduction to Nanoelectronics


New technologies need new materials with higher physical, chemical and mechanical properties. When the grain size is usually reduced to below 10 nm, most electronic and optical properties differ. Their mechanical, chemical and many physical properties, however, start to differ substantially from bulk below 50-100 nm. Nanomaterials can be defined as those materials that have at least one of their nanometric range dimensions, below which the property of interest varies greatly compared to microcrystalline materials.



Impacts of nanotechnology


Smaller size means operations for a given output at higher frequencies, greater functionality, lower manufacturing and lower power. Memory space and data rates for transmission will increase. Health diagnostic equipment is faster, more practical, and more precise.(Lab-on-chip). In pharmaceutical products, nano-particles enhance their absorption inside the body and make them easier to administer, often through a combination of medical devices.


By constructing vehicle parts that are lighter, stronger and more chemically resistant than metal from nanocomposite materials, vehicle fuel efficiency and corrosion resistance can be improved. Without a substantial increase in weight, thickness or rigidity of the fabric, nanoparticles or nanofibers in fabrics can improve stain resistance, water resistance, and flame resistance.


Limitation of microelectronics


It seems fair that Moore's law would have to slow down the pace of scaling down.


Several factors are linked to technical limits:


The amount of heat produced by the energy consumed and which cannot be extracted due to the material's thermal conductivity limits and the growing number of overlayers. As the size of the area to be doped is reduced to about 0.1μm3, the number of doping atoms becomes so low (about 10) that it is not possible to properly monitor the "parameter spread" in fabrication.


Physical Boundaries:


Thermal limit: The energy required for a bit of writing should be many times kT, which is the average thermal fluctuation energy.


Relativistic limit: it is unlikely for signals to spread faster than the speed of light


Principle of uncertainty: According to the Heisenberg principle of uncertainty, the energy & time required to write or read a bit should be related to ΔE.Δt ≥ h


Developments In Nanoelectronics & Optoelectronics


Evolution of the minimum feature size of a Si DRAM


Today, it is assumed that current Si technology will continue to develop one order of magnitude lower towards feature sizes, i.e. L ~10 nm; But below this scale, it will be appropriate to build transistors based on new concepts such as single electron transistors, resonant tunnelling devices, etc.


The principles of mesoscopic & quantum physics must explain the function of this new form of system. Due to developments in the deposition of very thin films to form heterostructures in which electrons could be limited to a 2D mesoscopic device, evolution towards nanoelectronics was possible. We are presently close to the limits of traditional optical lithography and other nanolithographic techniques of high resolution.


Superconducting electronics: consists of 2 superconducting layers separated by a very thin isolating film of oxide, which can be tunnelled by superconducting electron pairs. High switching rates, sum of dissipated power is very low and the resistance of interconnect superconducting lines is virtually null.


Spintronics-which exploits electron spin orientation. By enclosing a semiconductor layer (base) sandwiched between two ferromagnetic layers (emitter & collector), electron-spin transistors are constructed. Electrons gaining the emitter's magnetization state will only pass through the collector through the base if their spins are compatible with the collector's magnetization.


Molecular electronics: This is based on the various states or configurations that molecules can take, such as "trans" or "cis" as well as the unpaired electron spin parallel or antiparallel alignment.


Bioelectronics: trying to replicate nature - for nanotechnology norms, a neuron is very large. The parallel processing capabilities as well as their 3D architectures and the topology of the interconnects are what nanoelectronics try to mimic biological neurons


Optoelectronic Integrated Circuits (OEIC): laser diodes are generated in chips using standard integrated circuit technology, combined with transistors and optical interconnects.

Tuesday, 10 November 2020

Effect of Maternal Depression on Child Development

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Introduction

Postpartum depression can occur in mother during the postnatal period and can extend into longer periods. The postpartum depression can cause distressed mood, weariness, loss of appetite, loss of normal sleep patterns, anxiety and suicidal thoughts in mothers. The chance of women with postpartum depression, to experience depression in future is up by 50 to 60 %. Women with a history of mood depressions, or a family history with psychological disorders have a high chance of suffering from depression. Some of the other reasons for the postpartum depression are, stress factors such as negative life incidents, poor marital relationships, having a physically disabled child or with mental disabilities, lack of social support, drug abuse, and hostile living conditions. Compared to the depressions which occur for regular individuals, postpartum depression tends to be milder, with lower levels of anxiety and agitation. The effects of postpartum depression on a child is not confined to infancy. The effects can be seen even in a school aged child or even in the adolescent stages.


Like in any health issues, the most effective way of containing the postpartum depression is by preventing its occurrence. Education sessions should be imparted to the mothers and pregnant women for helping them prepare to face the challenges of parenting. Development of a strong mother-child bond is absolutely necessary for the healthy development of a child. Psychotherapy sessions, interventions to improve the parenting skills and maternal sensitivity are available to improve the conditions of  mothers who suffer from maternal depression. Home visiting by health workers and nurses and analyzing the situations along with giving expert advice can also help the effected mothers.

 

Types of effects for maternal depression


A mother’s responsive and sensitive care is crucial for children’s optimal development. According to some available data about 13% of women experience maternal depression problems. Maternal depression, also known as prenatal depression make the mothers more lax, inconsistent and disengaged with their child. This impaired parenting is of prime concern during children’s early years when the mother's care and stimulation is required for the development of the child. As a result, such improper and impaired parenting can hinder the early development of child. Maternal depression is of great social concern, and effective intervention approaches are required to prevent or reduce its negative impact on child's development. The maternal depression is associated with children’s developmental problems including impaired socio-emotional, cognitive and behavioral functioning.


Socio-emotional functioning


Children of depressed mother are more likely to express negative effects. Such children find it quite difficult to  control their anger. They tend to have an insecure attachment and poor interpersonal skills. Experiencing high stress level is another characteristic of such children

 

Cognitive functioning


Children of the depressed mothers also show impairment in cognitive development. Such children show less advanced language development . The academic skills of the child tend to suffer. They have a lower self-esteem, and display other cognitive vulnerabilities like depression or other similar disorders.


Behavioral functioning


At the behavioral level, children of depressed mothers are characterized as having increased sleep problems and have less control over their anger and aggressive behavior. They are found to be less cooperative and are less active. They are also at heighten risk of developing internalizing (e.g., depression) and externalizing (e.g., aggressive behavior) problem behaviors in comparison to children of non depressed mothers.

Better social and home environment can help in reducing the effects of maternal depression. The paternal guidance and care can improve the conditions of the child. In contrast, the conflicts between parents can further degrade the conditions of children who are already victims of maternal depressions


Effect of maternal depression on infants


Active interaction of infants and mother is absolutely necessary for the development of infants. Depressed mothers display some disordered interaction with the infant. These interactions can be hostile or unresponsive type. In case of mother's hostile behavior, the infant experience anger and they turn away from mother to avoid the hostility and develop an angry and protective style of adjustment. The unresponsive mothers on the other hand, are unresponsive to the child's needs and activities. The children in such a situation, due to a lack of support and ineffectiveness from the mother's side, finds it difficult to cope with the conditions and challenges, thus becoming more withdrawn and laxative in character. The children need the guidance and soothing presence of parents to develop ways to regulate their emotions. The infants ate unable to regulate their emotions by themselves. The cognitive development of Infants of  depressed mothers is also affected adversely. Such infants  show patterns of abnormal behavior and arousal. Their ability to keep clam and perform non social learning tasks is affected adversely.


Effects of maternal depression on preschool children


Depressed mothers fail to imbibe the pressure felt by a child. They fail to effectively solve problems faced by the children or improve their mental regulations. The child cannot rely on the mother for getting ample support or finding a viable solution for their problems. The studies show that the victim children were passive in nature. They showed less maturity and autonomous behavior. Such children are more vulnerable to internalizing and externalizing problems . Children of depressed mothers have low interaction sessions and they tend to respond adversely even to friendly approaches. Their interest for physical play and engagements are minimal.


Studies shows that children who experience the insensitive maternal interactions shows poor cognitive development and functioning. According to some recent studies boys are found to be more affected by the mother's untoward mental health conditions and interactions. Some other concerned areas of cognitive development, such as cognitive-linguistic functioning, ability of perception and performances are also found to be adversely affected.


Effect of maternal depression on school age children


The child's adjustment capabilities depended on the severity of maternal depression. The children of depressed mothers show increased depression, anxiety and conduct disorders. The studies showed that the risk of psychopathology in affected mother's children is very high compared to others. The emotional and mental problems in mothers affect the learning and academic performance of the children. Such children seems to develop attention deficit/hyperactivity disorder (ADHD) . The fact was discovered through a detailed study in children of age group 4 to 17 years. The affected mother's child shows lower IQ levels, attention problems and difficulties in mathematical reasoning . They displayed a requirement for special education and care. In addition, the boys are found to be more affected by these adverse situations.


Effect of maternal depression on adolescent


The adolescent age of a person is the transitional period. It is transition from childhood to adulthood. There is an increased need of guidance and control during this phase of life. The inactive or hostile behavior of mother will have a negative influence on the person. The adolescents with a depressed parent shows high levels of depression and anxiety disorders. They can develop certain behavioral disorders such as drug abuse, usage of liquor, violent behaviors etc. Adolescent offspring's of depressed mothers developed phobias and panic disorders. The attack of depression was more common in the age group of 15 to 20. The learning disabilities like ADHD and lack of concentration seen in school children also persists in the adolescent age. So the academic performance suffer.


Risk factors


Contextual factors: Living conditions of a mother and child contributes to the depressing state of mind in mother. Often the conflicts between parents or stressful life events affects the mother's mental stability. The support of other family members and economic condition of family plays a major role in state of mind. Lack of education, social status and economic stability can affect the efficiency of parents.


Role of fathers : The children of depressed mothers tend to interact more with their father. In such situations paternal control and guidance is of prime importance. The child tries to draw confidence from their father. The father can act as a buffer between the child and the depressed mother. He can be helpful is imbibing some pressure and making the situation better.


Characteristics of the child: Sex differences have determined the depth of effects due to maternal depression. As described earlier, boys are found to be more affected by maternal depression. The temperamental factors of the child decides upon how much a child gets affected by the maternal depression. Children with better adaptive and cognitive development can effectively utilize the availability of other resources to negate the effects of maternal depressions. They can attract the attention of other family members and receive care and guidance. The child can realize the shortcomings or illness of their mother and make adaptations.


Treatment and  preventive methods


Preventive and Intervention Policies: To reduce the effects of maternal depression on the children preventive and intervention measures should be used. The parents should be educated about the positive benefits of a healthy pregnancy. They should imparted with knowledge and skills for child rearing and guidance. The recent researches emphasis on the importance of interventions that helps in improving the parenting skills and thereby improve the mother child interaction. The community workers and nurses can make a regular home visits to make the mothers more sensitive about their children's needs and development. They can increase the empathy and attachment of mother towards her child. They can help in improving paternal involvement to reduce the effects of maternal depression. The mothers who go through such depression phase should be given extra care and emotional support by other family members. The intervention practices have helped in making improvement in mental health and development of affected children. While the interventions are made, it should be considered that different policies and methods are required for different situations. So the methods should be flexible and dynamic.


Antidepressants: The use of antidepressants to treat the pregnant women should be done with utmost care. The chemicals can cause damage to the fetus and may cause health issues to the new born. The usual chemicals like tricyclic antidepressant can be replaced with less toxic selective serotonin retake inhibitors. The chemicals which are used for treatment should be imparted in maximum possible lowest of doses. The effect of chemicals used by mothers can be seen in the newborns as these chemicals pass on to the newborn from mother through breast feeding.


Role of Doctors: The maternal depression often go unnoticed and so they are left untreated. The pediatrician or doctors who examine the child and mother, can recognize the problems and risks at an early stage and take appropriate steps. The doctors can provide valuable advice and guidance to the depressed mothers along with medication to improve the condition.


Conclusion


Maternal depression has been found to affect the children of age group belonging to infancy up to adolescence. The lack of maternal care effects the mental development of child. The ability of child to cope with situations, problem solving capabilities, learning ability all gets affected. Early detection and intervention methods are found to be helpful in eliminating the depression in mothers. The most challenging factor about the maternal depression is that, it often goes unnoticed. A constant monitoring of health workers is required to alleviate the concerns raised by this issue. We cannot altogether put such mothers on medication, because it can affect the health of fetus.

Sunday, 8 November 2020

Logistics and Supply Chain Management in Chocolate Industry

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Logistics manages the transportation and delivery of  the final products from the site of manufacture to the hands of  final consumers. A supply chain is an organization of systems or associations engaged with the worth addition measure in each stage before an end result is shaped lastly and conveyed to the hands of definite buyers. The entire flexibly chain cycle can be planned to get a snappy visual reference of the progression of crude materials from hands of raw material providers to the hands of manufacturers and afterward the progression of finished products to the hands of the customers. This report analyzes the various stages of a supply chain and logistics. The relationship between each of the stages has been studied. For the purpose of analysis the supply chain mapping of chocolate industry has been taken. The supply chain map of a chocolate industry is as given below.

Fig: Supply chain map of a chocolate industry

At first we can have a look at various stages in a supply chain map. The main raw material for the production of chocolate is cocoa. Cocoa is mainly grown in Western African countries. These cocoa beans are imported from these tropical countries. The beans are collected from the farmers and stored. They are transported to harbors, from where they are shipped to other continents or countries. The coca shipment is received at the respective country' harbor. From there the cocoa beans are transported to the preprocessing centers. At these centers the cocoa is separated to cocoa butter and cocoa mass. The cocoa butter is the main requirement for the chocolate manufacturing process. The butter mass is transported to the chocolate production centers. The butter mass along with sugar, milk powder and vanilla is used to make the chocolate. We should also look into the issue of procurement of these raw materials in addition to cocoa. Milk powder and sugar are often available with local suppliers. So we can obtain this from such suppliers, and hence reduce the transportation costs. Vanilla is not available in all local markets and they may be imported like cocoa beans. After the production process, they are packed and transported to the storage centers. From there they are delivered to distribution centers. From distribution centers they are taken to supermarkets and shops, from where the products finally reach the hands of consumers. Logistics deals with taking the finished products to the consumers. It is not an easy task. For proper working the logistic function we need to have an idea about the local markets, people' tastes, customs duties information's and lots of similar data. The mapping of supply chain operations increases the visibility of each entity in the chain. It helps us to recognize the risk factors and make adjustments accordingly.

 

Importance of Logistics in Chocolate Industry


The chocolate industry is growing at a faster pace in the recent times. The increasing demand for chocolate in the overseas markets are providing an opportunity for the chocolate companies. They are spreading their business to new horizons rather than remaining stagnant in the already existing markets. They have become less dependent on the local markets. The logistic play roles can provide an information about local market demands and opportunities. They can also help in clearing the customs formalities. Since chocolates are perishable food item, they need a quick, timely and safe transportation to the destinations. Logistics is extremely important for such delicate items. We can have a quick look of the need for an efficient logistic system for the chocolate industry.


1. Transporting safely and securely


Chocolates are very delicate in nature and so they should be delivered in time and safely .While transportation it should not be affected by humidity or high temperature. It will degrade the quality of chocolates. To  ensure that the chocolate is transported safely and arrive on time, make sure you choose a reliable logistic  provider.


2. Meeting and maintaining customer demand


To meet the customer demand, timely delivery of products is essential. On certain occasions like local festive seasons, chocolate demand can go up. The logistic mechanism should be flexible enough to work extra for meeting such demands. The logistics provider can also provide us with local market demand data. The products should also be immaculately clean and free from contamination while sending over long distances.


3. Customs duties and regulations


The ever changing duties and taxes can be tiresome for the manufacturers for import of raw materials as well export of finished products. The calculations can be quite challenging, especially in the food products industries. The logistic providers can update us with the latest customs duties and regulations.


4. Choosing the right markets


The logistics experts can provide us with some useful data and advice or opinions Their knowledge and experience can prove invaluable for both short and long-term decision making.


5. Language barriers


Communication is an important aspect throughout the supply chain. When shipping overseas, language barriers can provide with difficulties in tracking the product chain. By ensuring good ground support and local we can avoid any potential challenges of this nature.

 

Importance of Supply Chain Analysis in Chocolate Industry


Supply chain analysis helps in delivering the desired product to the right people at the required time. The activities starting from purchase of raw materials, production and transportation is analyzed by mapping of supply chain. It helps in easy analysis to identify the risks and make improvements in the production and marketing process. The supply chain analysis has following advantages in a chocolate industry.

 

1. Recognize the risks and visibility


By mapping the supply chain and making an analysis, we get an idea about the providers of raw materials, manufacturing and transportation. So we can analyze the potential risks created by each entity in the chain. The ignorance about a higher or lower tier is removed. In case of chocolate production, the availability of cocoa beans is an important factor. Famine or other natural disasters in your producers' area can create a shortage of cocoa beans and affect the production adversely. So if you know about your producer's, you can be alert about the existing conditions and look for other alternatives. So it is important for the manufacturer to know about each entity in the supply chain. So for better visibility we need to create a global supplier database if we have to look for an alternative in case of an emergency. The inflations can be helpful in creating a long term relationships with the suppliers and this can help in getting the raw materials even when the sources are scarce.


2. Build a map


The most effective way of analysis of material or product flow is to mp the supply chain. Similar to a data flow diagram it shows the each stage in processing. We can have a quick reference of the processing and marketing from the mapping. Relevant data is required from each stage of supply chain to make a reliable supply chain mapping.


3. Work collaboratively


Supply Chain mapping can be a complex work. For a chocolate industry they have to track the suppliers of cocoa, vanilla and other raw materials. Different chocolate industries might be getting the raw materials from common providers. So by sharing such non sensitive information can be helpful in creating supply chain maps.


4. Supply Chain Management


Supply Chain management deals with sourcing, production, distribution and transportation. They also provide inputs to data collection, business administration, optimization of process etc. The members of supply chain operation management members need a variety of skills like good communication ability, strong problem solving and analytical ability and in depth business knowledge.


The supply chain can be complex. The cocoa providers informations are often incomplete. The indirect supply chains can provide us with difficulties in data collection. The data collection process is tiresome especially in case of import and exports. The chocolate industries raw material cocoa is often imported from Western Africa.

Wednesday, 4 November 2020

Risk Assessment of Covid 19 Pandemic

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Risk Assessment of Covid 19 Pandemic

Introduction


2020 has been a year marred by Covid 19 Pandemic. The disease which is believed to have originated in the Wuhan province of China took the global economy in a deep crisis. The social and economic structure of our society was in disarray. USA has been one of the worst affected Nations in the world. Covid 19 is creating havoc around the world with almost 47 million cases and around 1.2 million deaths in 2020. USA has been the most affected by the pandemic and it has the highest number of death and the infected cases compared to other world nations. Scientists are working around the clock for developing vaccine  against the virus. Vaccine is expected to arrive in the market by the next year 2021.  The Global spread of the virus has disintegrated health systems and disrupted the social and economic development. Many countries have imposed lockdown strategies and isolation methods to control the spread of disease. This measure has helped them to contain the disease to a great extent. The world is slowly recovering from the economic crisis pandemic has caused. But it may take time for the full recovery of our economy and the world is waiting for the arrival of an effective vaccine against covid-19. The covid-19 can be fatal, particularly for the aged persons and others who are having health issues like diabetes, cardiovascular disease, hypertension, lung disease etc. (Alexandrovich et.al, 2020). The virus spreads at a rapid rate and grows exponentially. There are also cases where the patients don't have any visible symptoms. So that makes it more difficult to detect in such conditions and the carriers will be spreading the disease without the knowledge of being affected.


Risk Analysis


We need a renewed focus on the public health systems to contain the  pandemic and slow down its transmission. It can affect all sections of the society and it have adverse effects on the economy as well as the social system . We can have a look at the different sources of the transmission of the virus. Social distancing is an essential strategy for preventing the spread of disease. Lockdown has been enforced on by the government systems to prevent the crowding of people and enforce the social distancing. It was an effective method to contain the spread of virus, but unfortunately we can't continue the restrictions for very long periods of time since it will affect our economy adversely. So we can identify certain issues which has increased the risk of transmission virus. Frontline health workers always have a greater risk of getting infected  since they come in contact with the affected people more often. They need to follow strict personal hygiene and use safeguard strategies to keep themselves safe and also to arrest the spread of disease to others. Tourism and immigration  have been some of the reasons for the spread of disease. People travelling to or from other countries can bring the disease along with them into our nation. Also there is an equal chance of bringing the disease when citizens travel two other countries and return (Desmet et.al., 2020). Government imposes ban on travel for some period of time to prevent the disease. Some pubic common use areas such as restaurants, toilet public transport system can be a source of disease spread. When we use such public areas there is a need of maintaining high hygiene and personal social distancing. The face needs to be covered with a mask and make yourself clean with sanitizer frequently. Try to avoid the crowded areas and follow the rules and restrictions imposed by the government. The government can put monitoring and supervision techniques to make sure that the citizens are following directions and maintaining procedures. Limit social gatherings in homes and other common places to maintain the social distancing rule. Another area of consideration is for workers living together and travelling together to work together. If any of the workers gets the disease then there is a high chance of the disease getting spread among the whole group of workers (Wilder et.al., 2020).


We have to make subtle changes in our lifestyle to help stop the spread of the pandemic. Social gatherings and other crowded areas are sources of spreading for the disease. The government of different countries imposed restrictions on such gatherings and restricted the number of persons who could attend functions and funerals. The borders of the countries were closed for some time to prevent entry and exit of people . Many IT companies and educational institutions have shifted to online mode. The workers and faculty can work from their homes and thus avoid the need to travel and mingling with people. This reduces the risk of getting the disease read extend.


However, very few strategies and associated risk assessments will take into account the occurrence of an epidemic or similar structural disorders. Even if a company has an infection on its risk radar; Even the most experienced boards and executives in these situations may have limited experience and system recognition so concerns may be limited to their staff and health care costs. As a result, strategies that are “hot from the press” or at various stages of development are inappropriate due to the 2019 corona virus epidemic (COVID-19) and the monumental effects of this global event. In many cases, while employee health is still important, immediate attention should be paid to travel restrictions, supply chain disruptions, and celebrity concerns about how the business is reacting. On infection. These awkward situations that have already occurred are exacerbated by the impending global recession and the emergence of ever changing challenges - it is difficult to say whether the recession and the effects of COVID-19 will begin to end (Haq, M. N., 2020).


What we see is that COVID-19 infection is proving to be a truly interrelated risk, manifesting itself very quickly due to its systemic nature. Our concern for medical services has led to many of our current mitigation efforts focusing on ‘curving the curve’ to further address risk. While giving such a response can reduce the severity of the effects, one can expect these effects to be long lasting and long lasting. In general, strategies produce a version of the future, often without understanding how that version works. However, there are many scenarios where some business conditions may change temporarily after COVID-19, while we can be confident that others will be more stable.


A firm can present a strong argument for using a method that uses an emotional lens for the situation; Not only does it identify the traditional characteristics of risk (i.e. probability and significance), but there are also interrelationships and velocity measurements that are increasingly important for such a systemic risk. By realizing that risks operate as an interconnected network, companies can identify the most influential risks and best goals and use risk reduction techniques to positively impact the key challenges and opportunities they face. They face a Govt-19 world. By deliberately introducing the risk dimension for infection, the analysis of the application of such a method illustrates the importance of considering the clusters of related risks and explores how the risk of infection may alter the potential risk associated with infection. The analysis also reveals that compared to the impact of individual risks captured with traditional approaches, any domino risk has greater severity and speed of danger when viewed in clusters (Courtemanche et.al., 2020).


Risk Evaluation


Effect of covid-19 runs very deep and it may take time for the economy to recover from such losses. Demand and supply shock has been a feature of the economic crisis brought about by this pandemic. The health systems were found inadequate to contain the pandemic and temporary hospitals were set up to accommodate the patients. Quarantine, lockdown unemployment and business closures, reduced the demand for goods and services, that further degraded the economic situation . Job losses has been a regular feature. The adverse affects have been greater for women and the non-white workers. The data collected shows a decline of 8.7 % in the case of consumer goods sales from February to March 2020. It was the largest decline in the recent years since the collection of data has begun. The good news is that the consumer goods economy is slowly recovering from the crisis and this was shown in consumer goods sales, when it increased by 12.7 % from April to May. Another area of concern is the industrial production. The output from industrial production decreased to unknown levels . Machine tools, plastic machinery, steel production are the highly affected industries (Haq, M. N., 2020). The small business revenue has decreased by almost 20 percentage since January 2020.


The covid-19 has affected the unorganized sector to a great extent. It has left thousands jobless and is rapidly increasing the unemployment. The education sector has been in complete lockdown following the attack of covid-19. The students are continuing their education through online means. The effectiveness of such online education does not match to the direct classroom sessions. It can also negatively affect the academic progress and mental development of the young generation. Tourism and hospitality sector is also facing the loss of revenue due to the current scenario. The countries have closed their borders and put restrictions on travel. Apart from the economic losses, we can have a look at the social burden which was imposed by the  covid-19. Social distancing and quarantine measures have kept friends and relatives apart without any social engagements. The continuous seclusion process can have a heavy toll on the mental health of people. The anxiety about the disease is also increasing the negative effects on the mental health of people. Now, since the IT companies and certain other firms changed their work pattern, the employees are made to work from home for long periods of time through computers and tablets (Desmet et.al., 2020). This is causing musculoskeletal disorders in certain persons because of using display screen equipments for long periods of time.


Spread of covid-19 has shown certain Geographic trends. It first appeared in densely populated areas and then shifted its presence to more rural areas. So it affects more, who have low access to hygiene and with lower social and economic conditions. It shows that some racial and ethnic minority groups have increased chance of getting affect. They were found to have low access to the health services and it was found that such groups make more often use of the   public transport systems. The government policies have also resulted in their low social and economic development.


Measures to overcome similar threats in future

 

The experience and investments made in emergency preparedness made in covid 19 scenario can be used to fight against such a similar crisis in the future. It will be easier to deploy the resources and make a timely response to the demanding situations in the future. Active surveillance, collaborating different sections and groups to work together and addressing the psychological needs can be done with greater efficiency using the experience. Early preparation is an important factor in dealing with such hazards. Systematic analysis of the data and assessing the situations deeply can be helpful in such situations. The flaws in our health system have been exposed by Covid 19 pandemic, and the government can take measures to rectify those drawbacks and strengthen the health infrastructure.

Friday, 30 October 2020

Improving Energy Efficiency and Air Circulation Using BIM Technology

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Introduction:


Building Information Technology (BIM) has been a revelation in the field of construction. It has helped us improve the construction field by making a digital representation of the building details. It gives an idea and 3D view about the functional and physical properties of each and every part of the building. Even a door or a window can studied to the minutest of details and improve the efficiency. It helps the Engineers and contractors to visualise the proceedings prior to the actual work and help reduce the waste and improve the efficiency level of the building. The project puts forward an idea to reduce the energy consumption for the building and also improve the air circulation. Energy reduction is of great importance in the current world and the proposed idea is of great significance. The air circulation can improve the mental and physical conditions of the occupants and hence have a good impact on the living conditions.


Background


The BIM technology helps create a 3D view of the building which helps for a better understanding of the space in building, materials used and the system as a whole. The softwares commonly used to develop a BIM model are Autodesk Revit, Autodesk BIM360, ArchiCad, Sketch Up. In the project a sustainable model of building is developed and compute the energy consumption of the building. In the BIM technology we can design a building considering the properties of lighting, shadows and natural sun light. While designing we can maximize the use of the natural sunlight and thereby reduce the artificial lighting requirements. Large amounts of energy is consumed for human comforts. We can improve natural air circulation and thereby improve the thermal conditions inside the building. A continuous movement of air will ensure better living conditions and reduce the need of artificial fan and AC. Smart building and design can also  utilize the solar energy available.

Figure: BIM Cycle

The energy analysis can be done making use of BIM authoring tools. The energy analysis report is obtained using Insight 360. The energy utilization of building is analyzed by Energy Use Intensity (EUI) in Kilowatt per year, and improvements are done accordingly.

For studying the ventilation, the 3D image of building developed is integrated with computational fluid dynamic (CFD) modelling within a BIM platform. It can improve the positioning of doors and windows of building, and hence improve the thermal conditioning inside the building. The 3D model is converted to CFD model to analyse the air circulation.

Improving Energy Efficiency and Air Circulation Using BIM Technology

For analysing the energy demand of building, first we create a conceptual level climatic study of the building. Then create an architectural and structural model of the project. For that make use of BIM authoring tools. The properties of materials used in each and every part of building can be given as an input to the tool. So all physical and parametric properties of the material is recorded in the tool. This will give an idea about the properties of materials like heat transfer coefficient, energy embodied value etc. After the analysis a report is made on the energy use by Insight 360 tool. The rest is analysed and Energy Use Intensity is calculated.

EUI.   = {Total Energy Consumption for building/ Total floor area}

The analysis report will also have many options like optimising operation schedule, building operations, lighting efficiency and others, to alter the energy consumption levels. The tools like Auto desk Insight can be used. It is a cloud based energy analysis tool, that can help in improving the energy and environmental performances of building and consider the solar and lighting approaches for the building.

The energy efficient model developed in such a manner can also have an improvement in the natural air ventilation facilities. The 3 dimensional BIM model can be transferred to SAT format for conversion of external air into a 3 dimensional format. Later it is sent back to BIM software and transferred into the CFD simulation software. The geometry of the work is simplified for analysis process. The most required places are considered and others are neglected. For inlet, the boundary conditions like air velocity air temperature are defined. All the specified parameters are specified and visualised in the CFD format. Turbulence flow and heat transfer models are developed in CFD. The CFD simulations are integrated with BIM platform, and it will give a better understanding of air movement. While returning to BIM model, make the required adjustments in physical model to improve the airflow by comparing with CFD model ippo. The final 3 D model is developed in the BIM platform.

Discussions and Conclusions

BIM is an ever growing technology and it can be used in various situations to bring further improvements in the construction technologies. Information about the weather conditions needs to considered while designing for a better natural ventilation. Average wind speed, humidity and temperature are given as an input to the designing tools. Energy and material wastage can also be reduced to a great extent using BIM technology. So by creating an energy efficient building the cost of building has been proved. With a further improvement of the ventilation properties of the building,   the living conditions inside the building has also been increased. So the proposed projects fetches both health and economic benefits. Computer aided Engineering has improved recently with the different tools available. Now we can study the wind loads on buildings, pedestrian comforts in urban areas, control and analyse the air quality, predict the spread of smoke and many. The benefits of the technology have a never ending list and we can strive to improve the living conditions and efficiency of our built in environment.

Saturday, 17 October 2020

Power Electronics Lab Viva Questions

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Power Electronics Lab Viva Questions and Answers


1. What you understand about the Safe Operating Area (SOA) of a power device?


The boundaries of voltage and current in which the power device can be operated without destructive failures can be determined by the SOA. The SOA of a bipolar power transistor is given below:


2. What are cycloconverters? List the different types of cycloconverters?


The main use of a cycloconverter is to convert a constant frequency, constant voltage AC signal to another frequency AC waveform. By synthesizing the output waveforms from the AC supply segments, this can be achieved.

There are mainly two types of cycloconverters

(a) Step down cycloconverter

By using forced communication, a step down cycloconverter gives the output with frequency lower than the input frequency.

(b) Step up cycloconverter

By using line communication, a step up cycloconverter gives an output with frequency greater than the input frequency.


3. What you know about the operational amplifiers (Op Amps)?


Basically op-amp is a integrated circuit (IC), which can be used to work as a voltage amplifier. An op-amp has two inputs with different polarity hence it is fed with a differential input. So op-amp has two different polarity inputs and single output. An op-amp circuit gets high gain i.e., the output signal is very high as compared to input signal. There are mainly two types of op-amps.

(a) Inverting op-amps:

A inverting amplifier possesses negative feedback. The input is given to the inverting terminal (-ve terminal) of the op-amp and the non-inverting terminal is grounded. R1 is the input resistance and R2 is the feedback resistance.

(b) Non-inverting amplifier

The non-inverting amplifier gives amplified output signal and the output is in phase with the input signal.


4. Write the equations for gains of inverting and non inverting amplifiers?


Gain of non inverting op-amp is

Gain of inverting amplifier is


5. What you understand about forced communication?


By the effect of external circuitry, the current flowing through the thyristor is forced to become zero. This process is termed as forced communication.

 

6. List down the different types of voltage controlled (voltage driven) devices?


The different types of voltage controlled devices are:

IGBT, MCT, IGCT ,SIT etc.

 

7. In AC mode, what does the voltmeter shows?


In AC mode, the multimeter shows  the Root Mean Square (RMS) value of voltage or current. In DC mode, the multimeter shows only the RMS value.

 

8. What you understand about the  holding current of a SCR?


The minimum mandatory current for holding the SCR in forward conduction state is known as the holding current. The SCR switches from the state of forward conduction to forward blocking state, if the forward current is less than the holding current.


9. What you understand about universal motors?


Universal motors can be used for working with single phase AC source as well as DC source. It is often known as single phase series motor and is a commutation type motor. The motor runs in the same direction, when we reverse the polarity of the line terminals of a DC series motor. We cannot run a DC series motor as a universal motor, even though both are built in similar manner. Universal motors are widely used for speed control and high speed application purposes.  They can be used in wash machines, power drills, kitchen applications and blowers.

 

10. What you know about the hard switching of a thyristor?


The SCR can be said to be hard fired, if the gate current is very-very higher than the required gate current. This will enhances the di/dt capability and reduces the turn ON time.

 

11. MOSFET or IGBT is used for high voltage applications?


IGBT is mostly preferred for high voltage applications. For breakdown voltage up to 1000 V, IGBT is commonly used.

Fig : IGBT

MOSFET are commonly used for breakdown voltage less than 250V. 

 

12. What is the process of commutation?


The direction of current flow is changed in a particular path of the circuit for turn off the SCR. This process is called commutation.

 

13. Discuss about the control strategies of chopper?


The different control strategies of chopper are:

Frequency Modulation (constant TON or TOFF , variable frequency)

Current Limit Control (CLC)

Pulse Width Modulation PWM (Variable TON, constant frequency)

 

14. What you understand about the latching current of SCR?


The minimum current required to turn on (latch) the SCR from forward blocking state to forward conduction state is termed as the latching current.


15. For isolating the power circuits, power semiconductor from the low-power circuits which components are used?


Transformers and Opto-Couplers

 

16. What you know about natural commutation?


The process of enabling the thyristor to turn off and the current flowing through the thyristor goes through a natural zero is called natural commutation. Natural commutation occurs in AC circuits.


17. For DC applications, is it possible for using fuses with an AC voltage rating?


Fuses can be rated for using voltage AC or DC.  Normally the DC voltage rating of fuses is half of the maximum AC voltage rating.

 

18. For Turn ON the SCR, what methods you know?


For turn on the SCR, different voltage triggering methods are used. They are:

 (a) Light Triggering

 (b) Gate Triggering

 (c) dv/dt Triggering

 (d) Temperature Triggering

 

19. List the different types of current driven (current controlled) devices?


The different types of current controlled devices are:

SCR

GTO

GTR

 

20. Discuss about the characteristics of an ideal op amp?


The different characteristics of an ideal op amp are:

(a) Infinite input impedance Rin, and so zero input current

(b) Infinite open-loop gain G = Vout / Vin

(c) Infinite bandwidth with zero phase shift and infinite slew rate

(d) Zero output impedance Rout

(e) Zero input offset voltage

(f) Infinite power supply rejection ratio.

(g) Zero noise

(h) Infinite common-mode rejection ratio (CMRR)

(i) Infinite output voltage range.

 

21. Relating to the commutation process, what are the different types of commutations you know?


(a) Voltage commutated chopper

(b) Load commutated chopper

(c) Current commutated chopper

 

22. Give some examples of power electronics applications?


(a) Speed control of motors

(b) Uninterruptible Power Supply (UPS)

(c) Switch Mode Power Supply (SMPS)

(d) ICU

 

23. What you know about a snubber circuit?


The snubber circuit is a series combination of a resistor and a capacitor in parallel with the SCR. The circuit is mainly used for the dv/dt protection of SCR.

 

24. IGBT or MOSFET is most commonly used for high frequency applications? Justify your answer?


Since MOSFET has low switching losses than IGBT, MOSFET is commonly used for high frequency applications. For the applications of frequency range upto 20 KHz, IGBT are used and for frequency range greater than 200 KHz, MOSFET are used.

MOSFET
Fig : MOSFET


25. What you know about the duty cycle of a chopper?


The duty cycle of a chopper can be defined as the ratio of ON time of the chopper to the total time period of the chopper.

26. List the advantages of freewheeling diode in rectifier circuits?


The advantages of freewheeling diodes are:

(a) Input power factor is improved

(b) The load current waveform is improved

(c) Prevents the output voltage from becoming negative

 

27. What you know about the firing angle (delay angle) of an SCR?


The firing angle also known as delay angle can be defined as the angle between the zero crossing of the input voltage and the instant the SCR is fired. When the zero crossing of supply voltage takes place, one pair of thyristor is forward biased. These SCRs are triggered after the delay angle (α).


28. What are the uses of special machines?


The limitations of general purpose motors (Induction motors, synchronous motors) are they are neither precision position nor precision speed motors. For the applications of high precise position and high precise speed, special purpose motors (Stepper motors, PMDC motors etc) are commonly used.

 

29. What you know about a Permanent Magnetic DC motor (PMDC)?


A PMDC is same as that of an ordinary dc shunt motor. In PMDC, the field is provided by permanent magnets structure instead of salient- pole wound field structure.

The major advantages of PMDC are:

(a) Low noise

(b) Small size

(c) Low manufacturing cost

(d) High efficiency

There are mainly three types of permanent magnets used.

(i) Rare-Earth magnets

(ii) Ceramic magnets

(iii) Alnico magnets