Load Frequency Control (LFC) Strategies in Renewable Energy‐Based Hybrid Power Systems:A Review

The hybrid power system is a combination of renewable energy power plants and conventional energy power plants. This integration causes power quality issues including poor settling times and higher transient contents. The main issue of such interconnection is the frequency variations caused in the hybrid power system. Load Frequency Controller (LFC) design ensures the reliable and efficient operation of the power system. The main function of LFC is to maintain the system frequency within safe limits, hence keeping power at a specific range. An LFC should be supported with modern and intelligent control structures for providing the adequate power to the system. This paper presents a comprehensive review of several LFC structures in a diverse configuration of a power system. First of all, an overview of a renewable energy-based power system is provided with a need for the development of LFC. The basic operation was studied in single-area, multi-area and multi-stage power system configurations. Types of controllers developed on different techniques studied with an overview of different control techniques were utilized. The comparative analysis of various controllers and strategies was performed graphically. The future scope of work provided lists the potential areas for conducting further research. Finally, the paper concludes by emphasizing the need for better LFC design in complex power system environments

Purposes to Seek Information Resources by Academicians of the Oldest & Leading University of the Sub-Continent: An Explanatory Study

Major goal of this research was to know the purposes of seeking information resources by the academicians at GC University Lahore. As an allied goal, effort was made to know the role of the university library in meeting information and research needs of the academic faculty. Mixed methods research design was adopted for meeting goals of the research. Explanatory Sequential Design (QUAN + qual) was utilized. Firstly, quantitative data was collected through the instrument of questionnaire and analyzed by SPSS Software. Qualitative data was collected from 30 seasoned academicians working in different departments of the university. Thematic approach was followed to make analysis of the qualitatively driven data. Results of the study show that academicians search information resources for the purposes of preparing lectures, for guiding research scholars and students, for presenting research papers, to keep up with current developments, for writing research articles and enhancing their general knowledge. Findings of the study show that respondents are satisfied with the resources and services of university library. Participants recommend the need of formal training for developing skills to search specific information resources through online sources. Findings of this study are limited to the teaching faculty at GC University Lahore Pakistan, a leading institute of the sub-continent. The study has practical implication for the authorities of the universities and policy-makers of Higher Education Commission, Islamabad to design services in accordance with the needs of faculty members of the university. The study has revealed purposes of seeking information resources by academic faculty of the university, role of the library and practical solutions to meet information and research needs of the teaching faculty members

Resource Sharing among Medical Teaching Libraries: A Developing Country Perspective

Resource sharing is a functional as well as financial need of any library. In this modern era of information technology while information explosion is at extreme, it is impossible for a library to cover the entire surface of available knowledge. Developed countries are actual beneficiaries of this practice where idea of resource sharing has been transformed into a formal practice. Developing South Asian countries are also working on this concept in order to adopt it as a practice. This study identified the resource sharing opportunities for medical teaching libraries in Lahore with reference to perception and willingness. The sample of this study encompassed 26 leading medical libraries of all public and private degree awarding institutions in Lahore, Pakistan. The survey research method was adopted for this study. Findings showed that resource sharing is a valuable practice. It enhances the level of user satisfaction. It adds value to library collections which is not limited to library books only. Libraries are willing to initiate resource sharing through creating union catalogues. This study could be applied to all medical libraries in Pakistan to develop a real time formal resource sharing network which would accelerate performance reaming in limited financial resources

A robust variable-structure LQI controller for under-Actuated systems via flexible online adaptation of performance-index weights

This article presents flexible online adaptation strategies for the performance-index weights to constitute a variable structure Linear-Quadratic-Integral (LQI) controller for an underactuated rotary pendulum system. The proposed control procedure undertakes to improve the controller s adaptability, allowing it to flexibly manipulate the control stiffness which aids in efficiently rejecting the bounded exogenous disturbances while preserving the system s closed-loop stability and economizing the overall control energy expenditure. The proposed scheme is realized by augmenting the ubiquitous LQI controller with an innovative online weight adaptation law that adaptively modulates the state-weighting factors of the internal performance index. The weight adaptation law is formulated as a pre-calibrated function of dissipative terms, anti-dissipative terms, and model-reference tracking terms to achieve the desired flexibility in the controller design. The adjusted state weighting factors are used by the Riccati equation to yield the time-varying state-compensator gains

FREQUENCY OF CAROTID ATHEROSCLEROSIS IN CEREBRAL INFARCTION

Objective: To know the frequency of carotid atherosclerosis in ischaemic stroke patients in our population using color Doppler ultrasound. Methodology: This is an observational study conducted in the department of Medicine Nishtar Hospital, Multan. All the patients admitted during this duration with CT scan proof of stroke were included in the study. Risk factors in all these patients were stratified. Doppler ultrasound was performed on all patients with ischaemic stroke according to the study protocol. Results: A total of 100 patients were included in this study over a period of five months. 66% of these were having cerebral infarction. Hypertension (72%), diabetes (35%), smoking (29%) and obesity (20%) were the common risk factors. The frequency of significant carotid atherosclerosis in acute ischaemic stroke patients was 21%. Conclusion: Carotid atherosclerosis is one of the most important indicators, predictors as well as an independent risk factor in the development of ischaemic stroke. KEY WORDS: Carotid, Atherosclerosis, Doppler ultrasound

EFFICACY OF INTRAVENOUS ACETAMINOPHEN VERSUS KETAMINE FOR POSTOPERATIVE PAIN AFTER ABDOMINAL HYSTERECTOMY

Objective; To determine the efficacy of intravenous acetaminophen versus ketamine for postoperative pain after abdominal hysterectomy. Material and Methods; A total of 114 women undergoing abdominal hysterectomy were taken in this study. The study was conducted from June 2017 to May 2018 at department of Anesthesiology, Nishtar Hospital, Multan. Results; Our study comprised of 114 ladies undergoing abdominal hysterectomy, mean age of the study cases was 54.13 ± 6.89 years (with minimum age of the patients was 39 years while maximum age was 68 years). Majority of our study cases i.e. 92 (80.7 %) had parity more than 3 and American Society of Anesthesiology (ASA) score level 1 in 93 (81.6%). Sixty one (53.1%) belonged to rural areas, while mean duration of surgery was 72.80 ± 11.32 minutes. Mean BMI level in our study cases was noted to be 23.98 ±4.17 Kg/m2 and obesity was present in 34 (29.8%) of our study cases. Efficacy was noted in 60 (52.6 %) of our study cases. Efficacy was 73.7% study cases in group A while 18 (31.6%) in group B (p=0.000). Conclusion; Our study results support the use of intravenous acetaminophen (IVA) for pain management in patients undergoing abdominal hysterectomy compared with ketamine. Intravenous acetaminophen is safe, reliable and effective for the pain management in postoperative abdominal hysterectomy patients which was associated with shorter hospital stay and cost effective for the suffering families. No adverse reactions were noted in this study with the use of intravenous acetaminophen. Keywords; Intravenous acetaminophen, Ketamine, Abdominal Hysterectomy.

Aflatoxins in dates and dates products

A total of 153 samples of dates and dates products (date cookies, date cake and date halva) from Punjab and Khyber Pakhtunkhwa, Pakistan were evaluated for aflatoxins (AFs) using HPLC equipped with fluorescence detection. Thirty eight out of 96 samples (39.6%) of different date varieties and 18 out of 57 (31.6%) samples of date products contained AFs. The total mean level of AFs ranged between 2.90 to 4.96 μg/kg and 2.76 to 4.80 μg/kg in dates and dates products, respectively. About 16 and 20 samples of dates were found above the permissible level for AFB1 and total AFs, respectively (i.e. 2 μg/kg, 4 μg/kg). Furthermore, two samples of date's cookies and one sample of date cake were found above the level of AFB1 and total AFs and three and five samples of date halva were found above the recommended limit for AFB1 and total AFs, respectively. The high occurrence of AFs may cause health hazards and limit exports

Aflatoxin M1 in milk from urban and rural farmhouses of Punjab, Pakistan

Aflatoxin M1 (AFM1) was determined in 107 milk samples collected from urban and rural farmhouses from Punjab, Pakistan, by HPLC with fluorescence detection. An incidence rate of 64% (38/59) in milk samples from urban farmhouses was found, with a mean concentration of 0.064 ± 0.023 μg L−1. In rural samples about 52% (25/48) of milk samples were contaminated with AFM1, with a mean of 0.04 ± 0.034 μg L−1. About 42% of milk samples from urban and 27% from rural farmhouses were well above the limit permitted by the European Union (EU). However, only 15% and 8% of milk samples from urban and rural farmhouses, respectively, exceeded the limit of USDA/Codex regulations. The results showed that the contamination of milk with AFM1 from Punjab, Pakistan, when compared with Codex limit is present and needs continuous monitoring. The awareness and education among dairy farmers on the potential health risks associated with aflatoxins should be communicated

Natural occurrence of aflatoxin B1 and aflatoxin M1 in “halva” and its ingredients.

A total 431 samples including halva (56), pistachio (71), almond (63), semolina (69), cardamom (34), raisins (46), halva puri (39) and wheat powder (53) were analyzed using HPLC equipped with florescence detector. The results have shown that 32 (57%) samples of halva, 45 (63%) pistachio, 43 (68%) almond, 46 (67%) semolina, 21 (62%) cardamom, 19 (41%) raisins, 21 (54%) halva puri and 22 (42%) of wheat powder samples were found contaminated with AFB1, and 11 (20%), 23 (32%), 34 (54%), 12 (17%), 11 (32%), 7 (15%), 9 (23%) and 11 (21%) samples, respectively were above the European Union permissible limit (2 μg/kg). The results have shown that 20 (59%) samples of halva that contained milk were found contaminated with AFM1 and 3 (9%) samples were found above the recommended limit for AFM1 i.e. 0.05 μg/kg. Limit of detection (LOD) and Limit of quantification (LOQ) for AFB1 and AFM1 were 0.04 μg/kg, 0.12 μg/kg, and 0.004 μg/L, 0.012 μg/L, respectively