LLC Resonant Converter Topologies For Plug-In Electric Vehicle Battery Charging

Recent improvements in battery technology and reduction in price have intensified interests in electrical vehicles (EVs) as these provide best means for pollution free and efficient transportation necessary for the sustainable development of the whole world. In near future, plug-in electrical vehicles (PEVs), which are equipped with on-board chargers, are expected to dominate the automobile market. Most commonly used on-board chargers consist of two stages with AC/DC converter as first stage and DC/DC converter as second stage. This thesis focuses on second stage whose function is to regulate charging voltage and current in accordance with battery’s charging requirements. The terminal voltage of EV battery varies over wide range during usage and it may discharge up to normally depleted or deeply depleted states. Therefore, the main challenge for DC/DC converter designer is to realize wide range of output voltage and current while maintaining good efficiency so that the converter is able to revive deeply depleted battery. To this end, this thesis contributes five novel topologies of LLC resonant converter for the DC/DC stage of on-board PEV battery charger which are: double LLC tank resonant converter, double LLC tank resonant converter with hybrid-rectifier, hybrid-bridge LLC resonant converter, hybrid-bridge LLC resonant converter with hybrid-rectifier, and interleaved LLC resonant converter with series connected voltage doublers. The first topology uses frequency control to achieve only depleted battery charging voltage range. Whereas, the other four topologies use mode changing with switching frequency control to extend the output voltage range for reviving deeply depleted battery, compared with conventional counterparts which use complex control techniques. Moreover, all the proposed topologies operate below resonance frequency for most extensively used normal battery charging range, therefore, power switches operate with ZVS and rectifier diodes with ZCS. The proposed topologies are designed for charging lithiumion PEV battery pack with terminal voltage as 420V when fully charged, 250V when depleted, and 100V or less when deeply depleted. The circuit configuration, analysis of operation, gain characteristics and design procedure of all the topologies are presented in details. Finally, all the proposed topologies are implemented and tested in laboratory and also simulated using MATLAB Simulink environment with 400V DC input and 1.5 kW maximum output power. The captured experimental and simulation results are presented in this thesis for validation of operation and performance of proposed converter topologies. The presented results showed that the four proposed topologies can effectively charge both normally depleted as well as deeply depleted battery, while the first topology can achieve only normally depleted battery voltage range. On the other hand, last two topologies have shown widest output voltage range of 50V–420V. Therefore, last two topologies have the ability to charge even very deeply depleted batteries. All the proposed topologies have peak efficiency higher than 95% at peak output power. However, the last topology which is interleaved LLC resonant converter with voltage doubler rectifier has highest efficiency of 95.65%. Moreover, this topology also has widest output voltage range of 50V–420V, so it can be considered as the best one among all the proposed topologies

How 5G wireless (and concomitant technologies) will revolutionize healthcare?

The need to have equitable access to quality healthcare is enshrined in the United Nations (UN) Sustainable Development Goals (SDGs), which defines the developmental agenda of the UN for the next 15 years. In particular, the third SDG focuses on the need to “ensure healthy lives and promote well-being for all at all ages”. In this paper, we build the case that 5G wireless technology, along with concomitant emerging technologies (such as IoT, big data, artificial intelligence and machine learning), will transform global healthcare systems in the near future. Our optimism around 5G-enabled healthcare stems from a confluence of significant technical pushes that are already at play: apart from the availability of high-throughput low-latency wireless connectivity, other significant factors include the democratization of computing through cloud computing; the democratization of Artificial Intelligence (AI) and cognitive computing (e.g., IBM Watson); and the commoditization of data through crowdsourcing and digital exhaust. These technologies together can finally crack a dysfunctional healthcare system that has largely been impervious to technological innovations. We highlight the persistent deficiencies of the current healthcare system and then demonstrate how the 5G-enabled healthcare revolution can fix these deficiencies. We also highlight open technical research challenges, and potential pitfalls, that may hinder the development of such a 5G-enabled health revolution

Role of Tax Administration System and Public Governance on Taxpayers' Compliance Behavior, Moderating role of Religiosity

Considering the fact that direct tax collection and tax to GDP ratio in Pakistan is very low and the budget dificit is covered using debts, which further increases the dificit in the next years. It was needed to study the tax administration system of Pakistan and its impact of compliance behavior. This study is focused on determination of the impact of tax administration system and quality of public governance on individual taxpayers’ compliance behavior, in the presence of religiosity as a moderating variable. Survey method was employed and 625 questionnaires were distributed using a self-administered questionnaire from the individuals across the five major cities of Pakistan. The response rate was 66% and 412 appropriate questionnaires were returned from the respondents. Results of this study showed that tax administration system and quality of public governance has a strong and direct impact on taxpayers’ compliance behavior whereas, religiosity has an inverse and weak impact on taxpayers’ compliance behavior. Furthermore, religiosity moderates the relationships of tax administration system from positive to negative and weaken the relationship between public governance and tax compliance behavior

Bureaucracy and Public Management Reforms: Evidence from Pakistan

The paper examines administrative performance and public management reforms in Pakistan. The study is based on the expert opinion of the civil servants gathered via 27 semi-structured interviews. Pakistan has inherited the administrative structure from the British colonial raj. Although there have been numerous reforms aimed at improving administrative performance, none of them have been implemented adequately. The changes pursued in the first two decades were related to enhancing the administrative performance by creating an adequate structure of administrative posts and ensuring a fair remuneration system. The first full reform package was presented in the 1970s with steps to improve the civil service performance and nationalization of significant banks and industries. The New Public Management (NPM) inspired the Pakistani government to adopt the policies of managerialism and privatization during the 1990s. The government intended to remove the status quo and privatize the public sector industries. This reform was successful only with regard to the privatization of some sectors and banks. The remaining reform programme failed mostly because of political instability, weak political will, political interference with the reform process, etc. The semi-structured interviews conducted with Pakistani civil servants tackled the public administration problems and their possible solutions. The respondents suggested that an indigenous public management model should be created. They indicated that the government should firmly support the implementation of reform measures. Civil servants should get salaries according to their expertise. There must be a well-defined and up to date performance and evaluation system able to ensure performance-based promotions, rewards, and punishments

Feasibility, Architecture and Cost Considerations of Using TVWS for Rural Internet Access in 5G

The cellular technology is mostly an urban technology that has been unable to serve rural areas well. This is because the traditional cellular models are not economical for areas with low user density and lesser revenues. In 5G cellular networks, the coverage dilemma is likely to remain the same, thus widening the rural-urban digital divide further. It is about time to identify the root cause that has hindered the rural technology growth and analyse the possible options in 5G architecture to address this issue. We advocate that it can only be accomplished in two phases by sequentially addressing economic viability followed by performance progression. We deliberate how various works in literature focus on the later stage of this ‘two-phase’ problem and are not feasible to implement in the first place. We propose the concept of TV band white space (TVWS) dovetailed with 5G infrastructure for rural coverage and show that it can yield cost-effectiveness from a service provider’s perspective

MEASURING INFORMATION LITERACY SKILLS OF MBBS STUDENTS

The main purpose of this study was to measure the information literacy skills of MBBS students at King Edward Medical University Lahore, Punjab Pakistan. The quantitative research method was used to carry out the study. A convenient sampling technique was used to collect data from the entire sample. The total number of respondents was 309 with a total response rate of 91.69%. SPSS 22nd version was used to analyze the gathered data from respondents. Descriptive statistics were applied to check the frequency, percentage and reported in the form of tabulation. Moreover, the mean and standard deviation was also found to find out the results. The results showed that respondents were usually able to decide where and how to find the information and select information most appropriate to the information need. However, respondents were occasionally able to identify a variety of potential sources of information, evaluate information critically, differentiate between fact and opinion, and limit search strategies by subject, language and date. The usage of internet resources was a strength and opinioned as good while ethical and legal use of information, computer literacy skills, use of searching techniques and tools for information retrieval, and research skills were opinioned as fair. The printed information literacy instruction was preferred by KEMU students whereas online courses, orientation by librarians and seminars and workshops were not preferred by the respondents

ASSESSMENT OF SURFACE WATER QUALITY OF RIVER KORANG

Water quality of fresh water basins in Pakistan is being degraded because of human actions. Surface water quality at Angoori road, Phulgaran, Baheria golf city which are the main tributaries of river Korang, Rawal Lake and WASA filtration plant were investigated during June and April. Physico-chemical parameters including heavy metal detection of the water samples and possible sources of contamination were analyzed. The study showed that the pollution level in all the sampling sites is rising because of discharge of domestic wastes, poultry waste, agricultural activities and solid waste dumping directly into the sites. Parameters like COD, DO, TA and TSS and metals like lead and cadmium exceeded the permissible limits as compared with USEPA, PakEPA and WHO standards. The contamination level is higher in June as compared to April. The two station Angoori road and Rawal Lake are more contaminated as compared to other sites. Moreover WASA filtration plant is working efficiently it decreases the amount of contaminants coming from all sites and the water quality is fit for drinking

Effect of seed layer on the performance of ZnO nanorods-based photoanodes for dye-sensitized solar cells

In this paper, zinc oxide nanorods (ZnONRs) were synthesized by chemical bath deposition (CBD) method at 90 °C by using zinc nitrate hexahydrate and hexamethylenetetramine as precursors. In a first stage, the ZnO NRs were grown on un-seeded and pre-seeded fluorine-doped tin oxide (FTO) glass substrates by direct CBD method to study the effect of the ZnO seed layer on the NRs structural, morphological and optical properties. The X-ray diffraction (XRD) analysis performed on the preseeded NRs revealed a pure ZnO hexagonal wurtzite crystalline phase, while the Field Emission Scanning Electron Microscopy (FESEM) unveiled that the pre-seeded NRs exhibit a smaller diameter, higher density, higher aspect ratio and improved orientation along the c-axiswith respect to the un-seeded NRs. In a second stage, the powder obtained by aging, centrifuging and drying the precipitates formed during the CBD growth was analyzed by XRD to assess its crystal structure and phase purity and subsequently coated on un-seeded and pre-seeded FTO glass substrates by doctor blade technique. The ZnO NRs based seeded and non-seeded films fabricated by the two methods were finally used as photoanodes in dye-sensitized solar cells (DSSCs). Interestingly, the employment of pre-seeded ZnO NRs films deposited by doctor blade technique in comparison to the counterpart electrodes synthesized by direct CBD growth has led to a noticeable increase in the DSSC photoconversion efficiency from 0.35 to 1.86%. On the other hand, the inclusion of the seed layer has effectively improved the fill factor of the DSSC I-V curves for both the photoanode deposition techniques