A hybrid artificial neural network - genetic algorithm for load shedding

This paper proposes the method of applying Artificial Neural Network (ANN) with Back Propagation (BP) algorithm in combination or hybrid with Genetic Algorithm (GA) to propose load shedding strategies in the power system. The Genetic Algorithm is used to support the training of Back Propagation Neural Networks (BPNN) to improve regression ability, minimize errors and reduce the training time. Besides, the Relief algorithm is used to reduce the number of input variables of the neural network. The minimum load shedding with consideration of the primary and secondary control is calculated to restore the frequency of the electrical system. The distribution of power load shedding at each load bus of the system based on the phase electrical distance between the outage generator and the load buses. The simulation results have been verified through using MATLAB and PowerWorld software systems. The results show that the Hybrid Gen-Bayesian algorithm (GA-Trainbr) has a remarkable superiority in accuracy as well as training time. The effectiveness of the proposed method is tested on the IEEE 37 bus 9 generators standard system diagram showing the effectiveness of the proposed method

Minimize the load reduction considering the activities control of the generators and phase distance

This study shows how to calculate the minimum load that needs to be reduced to restore the frequency to the specified threshold. To implement this problem, the actual operation of the electricity system in the event of a generator outage is considered. The main idea of this method is to use the power balance equation between the generation and the load with different frequency levels. In all cases of operating the electrical system before and after the generator outage, the reserve capacity of other generators is considered in each generator outage situation. The reduced load capacity is calculated based on the reciprocal phase angle sensitivity or phase distance. This makes the voltage phase angle and voltage value quality of recovery nodes better. The standard IEEE 9-generator 37-bus test scheme was simulated to show the result of the proposed technique

A voltage electrical distance application for power system load shedding considering the primary and secondary generator controls

This paper proposes a method for determining location and calculating the minimum amount of power load needed to shed in order to recover the frequency back to the allowable range. Based on the consideration of the primary control of the turbine governor and the reserve power of the generators for secondary control, the minimum amount of load shedding was calculated in order to recover the frequency of the power system. Computation and analysis of the voltage electrical distance between the outage generator and the loads to prioritize distribution of the amount power load shedding at load bus positions. The nearer the load bus from the outage generator is, the higher the amount of load shedding will shed and vice versa. With this technique, a large amount of load shedding could be avoided, hence, saved from economic losses, and customer service interruption. The effectiveness of the proposed method tested on the IEEE 37 bus 9 generators power system standard has demonstrated the effectiveness of this method

Load Shedding in Microgrid System with Combination of AHP Algorithm and Hybrid ANN-ACO Algorithm

This paper proposes a new load shedding method based on the application of intelligent algorithms, the process of calculating and load shedding is carried out in two stages. Stage-1 uses a backpropagation neural network to classify faults in the system, thereby determining whether or not to shed the load in that particular case. Stage-2 uses an artificial neural network combined with an ant colony algorithm (ANN-ACO) to determine a load shedding strategy. The AHP algorithm is applied to propose load shedding strategies based on ranking the importance of loads in the system. The proposed method in the article helps to solve the integrated problem of load shedding, classifying the fault to determine whether or not to shedding the load and proposing a correct strategy for shedding the load. The IEEE 25-bus 8-generator power system is used to simulate and test the effectiveness of the proposed method, the results show that the frequency of recovery is good in the allowable range

The global response: How cities and provinces around the globe tackled Covid-19 outbreaks in 2021

Background: Tackling the spread of COVID-19 remains a crucial part of ending the pandemic. Its highly contagious nature and constant evolution coupled with a relative lack of immunity make the virus difficult to control. For this, various strategies have been proposed and adopted including limiting contact, social isolation, vaccination, contact tracing, etc. However, given the heterogeneity in the enforcement of these strategies and constant fluctuations in the strictness levels of these strategies, it becomes challenging to assess the true impact of these strategies in controlling the spread of COVID-19.Methods: In the present study, we evaluated various transmission control measures that were imposed in 10 global urban cities and provinces in 2021 Bangkok, Gauteng, Ho Chi Minh City, Jakarta, London, Manila City, New Delhi, New York City, Singapore, and Tokyo.Findings: Based on our analysis, we herein propose the population-level Swiss cheese model for the failures and pit-falls in various strategies that each of these cities and provinces had. Furthermore, whilst all the evaluated cities and provinces took a different personalized approach to managing the pandemic, what remained common was dynamic enforcement and monitoring of breaches of each barrier of protection. The measures taken to reinforce the barriers were adjusted continuously based on the evolving epidemiological situation.Interpretation: How an individual city or province handled the pandemic profoundly affected and determined how the entire country handled the pandemic since the chain of transmission needs to be broken at the very grassroot level to achieve nationwide control

EXPERIENCES OF THE NURSING STUDENT IN LEARNING HAI PREVENTION AND CONTROL IN ASIAN COUNTRIES THROUGH THE USE OF SCENARIO-BASED SIMULATION: AN EXPLORATIVE QUALITATIVE STUDY

BACKGROUND: Healthcare-associated infections (HAIs) have posed a major threat to both patients and to the safety healthcare personnel worldwide. According to the World Health Organization, 10% of hospitalized patients are affected by HAIs worldwide. OBJECTIVE: The objective of this study was to explore the experiences of nursing students in learning HAIs prevention and control by the application of the scenario-based simulation pedagogy now in use in two Vietnamese and two Cambodian universities. METHODS: A qualitative study was conducted among 160 nursing students from 2 Cambodian universities and 2 Vietnamese universities, and by using the purposive-sampling method. The data were collected through a focus group discussion and analyzed by the Graneheim and Lundman method (Graneheim & Lundman, 2004). RESULTS: Two themes and six categories were generated. 1) First theme: factors for enhancing student learning on the prevention and control of HAIs by use of scenario-based simulation; and 2) Second theme: factors hindering students learning on HAI prevention and control by use of scenario-based simulation. CONCLUSION: The findings showed that SBS is an effective learning method for nursing students that can be applied to enhance the quality of nursing education in the Asian countries as SBS not only improves the clinical skills, but also the soft skills of nursing students. However, the effective outcomes and impacts can only be achieved in the context with the appropriate learning materials and equipment, simulation facilities and the instructors with pedagogical skills

SIMULATION AS A TEACHING METHOD FOR NURSING EDUCATION IN HEALTHCARE-ASSOCIATED INFECTION PREVENTION AND CONTROL IN ASIAN COUNTRIES: A QUALITATIVE STUDY

BACKGROUND: Applying simulation for nursing education, especially in healthcare-associated infection prevention and control (HAI-PC) in developing countries has limited evidence. The study was conducted to explore educators’ perceptions of simulation as a teaching method for nursing education in HAI-PC in two Vietnamese and two Cambodian universities. METHODS: An exploratory qualitative design was applied. A focus group of 37 educators from four universities was conducted for data collection. Inductive and deductive qualitative content analysis was applied in analysing the data. RESULTS: The core category was constructed to reflect educators’ perception of scenario-based simulation (SBS) as a teaching method for nursing education in HAI prevention and control. This main category included three subcategories: (i) enhancing nursing competence; (ii) preparing students for simulation; and [1] promoting simulation pedagogy competence. CONCLUSIONS: The findings identified the importance and benefits of applying simulation as a teaching method in nursing education. Additionally, it emphasized the necessity of enhancing knowledge associated with HAIs and providing additional training on simulation for educators to improve the quality of conducting simulations

Safety and efficacy of fluoxetine on functional outcome after acute stroke (AFFINITY): a randomised, double-blind, placebo-controlled trial

Background Trials of fluoxetine for recovery after stroke report conflicting results. The Assessment oF FluoxetINe In sTroke recoverY (AFFINITY) trial aimed to show if daily oral fluoxetine for 6 months after stroke improves functional outcome in an ethnically diverse population. Methods AFFINITY was a randomised, parallel-group, double-blind, placebo-controlled trial done in 43 hospital stroke units in Australia (n=29), New Zealand (four), and Vietnam (ten). Eligible patients were adults (aged ≥18 years) with a clinical diagnosis of acute stroke in the previous 2–15 days, brain imaging consistent with ischaemic or haemorrhagic stroke, and a persisting neurological deficit that produced a modified Rankin Scale (mRS) score of 1 or more. Patients were randomly assigned 1:1 via a web-based system using a minimisation algorithm to once daily, oral fluoxetine 20 mg capsules or matching placebo for 6 months. Patients, carers, investigators, and outcome assessors were masked to the treatment allocation. The primary outcome was functional status, measured by the mRS, at 6 months. The primary analysis was an ordinal logistic regression of the mRS at 6 months, adjusted for minimisation variables. Primary and safety analyses were done according to the patient's treatment allocation. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611000774921. Findings Between Jan 11, 2013, and June 30, 2019, 1280 patients were recruited in Australia (n=532), New Zealand (n=42), and Vietnam (n=706), of whom 642 were randomly assigned to fluoxetine and 638 were randomly assigned to placebo. Mean duration of trial treatment was 167 days (SD 48·1). At 6 months, mRS data were available in 624 (97%) patients in the fluoxetine group and 632 (99%) in the placebo group. The distribution of mRS categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio 0·94, 95% CI 0·76–1·15; p=0·53). Compared with patients in the placebo group, patients in the fluoxetine group had more falls (20 [3%] vs seven [1%]; p=0·018), bone fractures (19 [3%] vs six [1%]; p=0·014), and epileptic seizures (ten [2%] vs two [<1%]; p=0·038) at 6 months. Interpretation Oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and epileptic seizures. These results do not support the use of fluoxetine to improve functional outcome after stroke

Clinical and Functional Characteristics of Subjects with Asthma, COPD, and Asthma-COPD Overlap: A Multicentre Study in Vietnam

Introduction. Subjects with asthma-chronic obstructive pulmonary disease (COPD) overlap (ACO) share common features of patients with asthma and COPD. Our study was planned to describe the clinical and functional features of subjects with ACO compared to asthma and COPD patients. Subjects and Methods. Study subjects who met the inclusion criteria were classified into three different groups: asthma, COPD, and ACO groups. All study subjects underwent clinical examination and biological and functional testing. They were then followed for 6 months to evaluate the response to conventional treatment. Results. From March 2015 to March 2017, 76 asthmatic (mean age: 41 ± 22 years), 74 COPD (59 ± 13 years), and 59 ACO (52 ± 14 years) subjects were included. The percentage of subjects with dyspnea on excretion in the ACO group was higher than that in asthma and COPD groups (P 15/hour had a significant probability of risk for ACO (OR = 33.2, P<0.001, and OR = 3.4, P<0.05, resp.). Conclusion. Subjects with ACO share the common clinical and functional characteristics of asthma and COPD but are more likely to have sleep apnea. The majority of patients with ACO have a favourable response to combined treatment

ẢNH HƯỞNG CỦA ĐIỆN THẾ NGƯỠNG LÊN SỰ PHÂN BỐ ĐIỆN TỬ CỦA ARMCHAIR GRAPHENE HAI LỚP NANORIBBONS

We employed tight-binding calculations and Green’s function formalism to investigate the effect of applied electric fields on the energy band and electronic properties of bilayer armchair graphene nanoribbons (BL-AGNRs). The results show that the perpendicular electric field has a strong impact on modifying and controlling the bandgap of BL-AGNRs. At the critical values of this electric field, distortions of energy dispersion in subbands and the formation of new electronic excitation channels occur strongly. These originate from low-lying energies near the Fermi level and move away from the zero-point with the increment of the electric field. Phase transitions and structural changes clearly happen in these materials. The influence of the parallel electric field is less important in changing the gap size, resulting in the absence of the critical voltage over a very wide range [–1.5 V; 1.5 V] for the semiconductor-insulator group. Nevertheless, it is interesting to note the powerful role of the parallel electric field in modifying the energy band and electronic distribution at each energy level. These results contribute to an overall picture of the physics model and electronic structure of BL-AGNRs under stimuli, which can be a pathway to real applications in the future, particularly for electronic devices.Trong bài báo này, chúng tôi sử dụng phương pháp tính toán tight-binding (TB) kết hợp với phương pháp luận hàm Green để khảo sát ảnh hưởng của điện thế ngưỡng lên cấu trúc vùng năng lượng và các tính chất điện tử của graphene hai lớp biên armchair nanoribbons (BL-AGNRs). Các kết quả nghiên cứu đã chỉ ra rằng điện trường vuông góc có ảnh hưởng mạnh mẽ lên sự biến đổi và điều chỉnh của vùng cấm ở BL-AGNRs. Tại các giá trị điện thế ngưỡng của điện trường này, sự biến dạng trong cấu trúc vùng con và việc hình thành các kênh kích thích điện tử xảy ra một cách mạnh mẽ, bắt đầu từ các mức năng lượng thấp nằm sâu bên trong mức Fermi đến các mức năng lượng nằm xa điểm năng lượng 0 khi giá trị điện trường tăng lên. Từ đó cho thấy quá trình chuyển pha và những thay đổi về mặt cấu trúc xảy ra một cách rõ ràng ở các nhóm của vật liệu này. Trong khi đó, ảnh hưởng của điện trường song song lại kém quan trọng hơn trong việc thay đổi độ rộng vùng cấm, dẫn đến việc không xuất hiện điện thế ngưỡng trong khoảng giá trị rất rộng [-1.5V; 1.5V] ở nhóm bán dẫn-điện môi. Tuy nhiên, một điều đáng chú ý là vai trò quan trọng của điện trường này trong việc điều chỉnh cấu trúc vùng năng lượng và sự phân bố điện tử trên mỗi mức năng lượng. Như vậy, những kết quả trong nghiên cứu này góp phần để hoàn thiện một bức tranh tổng quan về cấu trúc điện tử của BL-AGNRs dưới ảnh hưởng của các tác nhân kích thích đồng thời hướng đến giá trị ứng dụng của vật liệu này trong tương lai, đặc biệt là trong những thiết bị linh kiện điện tử