Modelling and Optimizing Supply Chain Integrated Production Scheduling Problems

Globalization and advanced information technologies (e.g., Internet of Things) have considerably impacted supply chains (SCs) by persistently forcing original equipment manufacturers (OEMs) to switch production strategies from make-to-stock (MTS) to make-to-order (MTO) to survive in competition. Generally, an OEM follows the MTS strategy for products with steady demand. In contrast, the MTO strategy exists under a pull system with irregular demand in which the received customer orders are scheduled and launched into production. In comparison to MTS, MTO has the primary challenges of ensuring timely delivery at the lowest possible cost, satisfying the demands of high customization and guaranteeing the accessibility of raw materials throughout the production process. These challenges are increasing substantially since industrial productions are becoming more flexible, diversified, and customized. Besides, independently making the production scheduling decisions from other stages of these SCs often find sub-optimal results, creating substantial challenges to fulfilling demands timely and cost-effectively. Since adequately managing these challenges asynchronously are difficult, constructing optimization models by integrating SC decisions, such as customer requirements, supply portfolio (supplier selection and order allocation), delivery batching decisions, and inventory portfolio (inventory replenishment, consumption, and availability), with shop floor scheduling under a deterministic and dynamic environment is essential to fulfilling customer expectations at the least possible cost. These optimization models are computationally intractable. Consequently, designing algorithms to schedule or reschedule promptly is also highly challenging for these time-sensitive, operationally integrated optimization models. Thus, this thesis focuses on modelling and optimizing SC-integrated production scheduling problems, named SC scheduling problems (SCSPs). The objective of optimizing job shop scheduling problems (JSSPs) is to ensure that the requisite resources are accessible when required and that their utilization is maximally efficient. Although numerous algorithms have been devised, they can sometimes become computationally exorbitant and yield sub-optimal outcomes, rendering production systems inefficient. These could be due to a variety of causes, such as an imbalance in population quality over generations, recurrent generation and evaluation of identical schedules, and permitting an under-performing method to conduct the evolutionary process. Consequently, this study designs two methods, a sequential approach (Chapter 2) and a multi-method approach (Chapter 3), to address the aforementioned issues and to acquire competitive results in finding optimal or near-optimal solutions for JSSPs in a single objective setting. The devised algorithms for JSSPs optimize workflows for each job by accurate mapping between/among related resources, generating more optimal results than existing algorithms. Production scheduling can not be accomplished precisely without considering supply and delivery decisions and customer requirements simultaneously. Thus, a few recent studies have operationally integrated SCs to accurately predict process insights for executing, monitoring, and controlling the planned production. However, these studies are limited to simple shop-floor configurations and can provide the least flexibility to address the MTO-based SC challenges. Thus, this study formulates a bi-objective optimization model that integrates the supply portfolio into a flexible job shop scheduling environment with a customer-imposed delivery window to cost-effectively meet customized and on-time delivery requirements (Chapter 4). Compared to the job shop that is limited to sequence flexibility only, the flexible job shop has been deemed advantageous due to its capacity to provide increased scheduling flexibility (both process and sequence flexibility). To optimize the model, the performance of the multi-objective particle swarm optimization algorithm has been enhanced, with the results providing decision-makers with an increased degree of flexibility, offering a larger number of Pareto solutions, more varied and consistent frontiers, and a reasonable time for MTO-based SCs. Environmental sustainability is spotlighted for increasing environmental awareness and follow-up regulations. Consequently, the related factors strongly regulate the supply portfolio for sustainable development, which remained unexplored in the SCSP as those criteria are primarily qualitative (e.g., green production, green product design, corporate social responsibility, and waste disposal system). These absences may lead to an unacceptable supply portfolio. Thus, this study overcomes the problem by integrating VIKORSORT into the proposed solution methodology of the extended SCSP. In addition, forming delivery batches of heterogeneous customer orders is challenging, as one order can lead to another being delayed. Therefore, the previous optimization model is extended by integrating supply, manufacturing, and delivery batching decisions and concurrently optimizing them in response to heterogeneous customer requirements with time window constraints, considering both economic and environmental sustainability for the supply portfolio (Chapter 5). Since the proposed optimization model is an extension of the flexible job shop, it can be classified as a non-deterministic polynomial-time (NP)-hard problem, which cannot be solved by conventional optimization techniques, particularly in the case of larger instances. Therefore, a reinforcement learning-based hyper-heuristic (HH) has been designed, where four solution-updating heuristics are intelligently guided to deliver the best possible results compared to existing algorithms. The optimization model furnishes a set of comprehensive schedules that integrate the supply portfolio, production portfolio (work-center/machine assignment and customer orders sequencing), and batching decisions. This provides numerous meaningful managerial insights and operational flexibility prior to the execution phase. Recently, SCs have been experiencing unprecedented and massive disruptions caused by an abrupt outbreak, resulting in difficulties for OEMs to recover from disruptive demand-supply equilibrium. Hence, this study proposes a multi-portfolio (supply, production, and inventory portfolios) approach for a proactive-reactive scheme, which concerns the SCSP with complex multi-level products, simultaneously including unpredictably dynamic supply, demand, and shop floor disruptions (Chapter 6). This study considers fabrication and assembly in a multi-level product structure. To effectively address this time-sensitive model based on real-time data, a Q-learning-based multi-operator differential evolution algorithm in a HH has been designed to address disruptive events and generate a timely rescheduling plan. The numerical results and analyses demonstrate the proposed model's capability to effectively address single and multiple disruptions, thus providing significant managerial insights and ensuring SC resilience

Fuzzy Multi-Objective Linear Programming for Project Management Decision under Uncertain Environment with AHP Based Weighted Average Method

Smooth implementation and controlling conflicting goals of a project with the usage of all related resources through organization is inherently a complex task to management. At the same time deterministic models are never efficient in practical project management (PM) decision problems because the related parameters are frequently fuzzy in nature. The project execution time is a major concern of the involved stakeholders (client, contractors and consultants). For optimization of total project cost through time control, here crashing cost is considered as a critical factor in project management. The proposed approach aims to formulate a multi objective linear programming model to simultaneously minimize total project cost, completion time and crashing cost with reference to direct, indirect cost in the framework of the satisfaction level of decision maker with fuzzy goal and fuzzy cost coefficients.. To make such problems realistic, triangular fuzzy numbers and the concept of minimum accepted level method are employed to formulate the problem. The proposed model leads decision makers to choose the desired compromise solution under different risk levels and the project optimization problems have been solved under multiple uncertainty conditions. The Analytical Hierarchy Process is used to rank multiple objectives to make the problem realistic for the respective case. Here minimum operator and AHP based weighted average operator method is used to solved the model and the solution is obtained by using LINGO softwar

A Multi Constrained Transformer-BiLSTM Guided Network for Automated Sleep Stage Classification from Single-Channel EEG

Sleep stage classification from electroencephalogram (EEG) is significant for the rapid evaluation of sleeping patterns and quality. A novel deep learning architecture, ``DenseRTSleep-II'', is proposed for automatic sleep scoring from single-channel EEG signals. The architecture utilizes the advantages of Convolutional Neural Network (CNN), transformer network, and Bidirectional Long Short Term Memory (BiLSTM) for effective sleep scoring. Moreover, with the addition of a weighted multi-loss scheme, this model is trained more implicitly for vigorous decision-making tasks. Thus, the model generates the most efficient result in the SleepEDFx dataset and outperforms different state-of-the-art (IIT-Net, DeepSleepNet) techniques by a large margin in terms of accuracy, precision, and F1-score

Analyzing Tobin’s Q Ratio of Banking Industry of Bangladesh: A Comprehensive Guideline for Investors

Due to the share market crash in 2010-2011, the investors have lost confidence regarding the share market till now. Therefore, this study is an endeavor to giveaway to rethink about the share market of Bangladesh and to increase the confidence of the investors. For that, Tobin’s Q ratio used to analyze the share market in this study. Tobin’s Q represents the ratio of the market value of a firm's share capital to the replacement cost of the firm's share capital. Tobin’s Q is greater than one means stock is overvalued. Tobin’s Q is less than one means stock is undervalued. Again, Tobin’s Q is equal to one means stock is fairly valued. The study found that, the value of Tobin’s Q of the all sampling banks is gradually decreasing means moving the value of the stock from overvalued to undervalue. The value of Tobin’s Q of the all sampling banks is less than one in the year 2014 except Dutch Bangla Bank Limited (DBBL). The average value of Tobin’s Q of the banking industry is also decreasing and the average value of Tobin’s Q of the banking industry is less than one in the year 2014. Thus, the average stock value of the banking industry is moving from overvalued to undervalue gradually. Again, the value of Tobin’s Q of all sampling banks fell down drastically from the year 2010 to the year 2011 as share market has been crashed in those years. As a result, the average value of Tobin’s Q of banking industry also fell down drastically from the year 2010 to the year 2011. Therefore, the value of the share slopes down drastically from the year 2010 to the year 2011

Spectrum of thyroid dysfunctions among hospitalized patients with non-critically ill coronavirus disease 2019: A cross-sectional study

Background: Patients with coronavirus disease 2019 (COVID-19) particularly critically ill ones may present with different types of thyroid abnormalities. However, data regarding thyroid function tests (TFTs) among noncritical patients with COVID-19 are scarce. This study aimed to assess thyroid functions and their associations with the severity of illness among non-critically ill hospitalized patients with COVID-19. Methods: This cross-sectional study assessed TFTs in 87 (aged 18-65 years) RT-PCR-confirmed COVID-19 patients admitted to a tertiary-care hospital in Bangladesh. Diagnosis of non–critical illness and severity (mild, moderate, and severe) were defined by WHO’s interim guidance. Patients having known thyroid dysfunctions or taking drugs that may affect thyroid functions were excluded from the study. Serum TSH, FT4, and FT3 were measured by chemiluminescent immunoassay. Results: Majority of the patients (72%) had normal thyroid function. Among the abnormalities, the highest frequency was isolated hyperthyroxinemia (12.6%) and the rest were subclinical hypothyroidism (6.9%), subclinical thyrotoxicosis (4.6%), thyrotoxicosis (2.3%), isolated tri-iodothyroninemia (1.1%), and hypothyroidism (1.1%).  Serum TSH, FT4, and FT3 levels were similar across the spectrum of noncritical illness. No significant correlation was found between the inflammatory markers (C-reactive protein, ferritin, and D-dimer) and TSH levels. Conclusions: More than one-fourth of non-critically ill hospitalized patients with COVID-19 presented with a spectrum of thyroid abnormalities with isolated hyperthyroxinemia being the most common. However, TFTs had no significant associations with the severity of illness among noncritically ill patients with COVID-19. Bangabandhu Sheikh Mujib Medical University Journal 2023;16(2): 81-86

Depression among the Non-Native International Undergraduate Students Studying Dentistry in Bangladesh.

BACKGROUND: Bangladesh has been attracting international students with interests in various subjects recently. Every year students from different parts of the world come to study undergraduate and postgraduate courses, mostly at private universities in Bangladesh. This study evaluates the depression status among international students who are studying dentistry in Bangladesh. METHODS: This cross-sectional survey was conducted among International undergraduate dental students who enrolled in the Bachelor of Dental Surgery program in nine public and private dental colleges in Bangladesh. Participants were selected using a convenience sampling method. A total of 206 students completed the survey where 78.5% of them were female students and 21.5% students were male, and a CES-D 10-item Likert scale questionnaire was used for data collection. The Cronbach alpha for the 10-item CES-D scale for this population is 0.812. RESULTS: The majority of the students (79.5%) are below 24 years of age with a mean age of 23.22 years and standard deviation of 2.3, and are students who cannot communicate well in Bengali (Bangla), about 60% of them have experienced depression. About 77.3% (p < 0.00) of the international students having financial difficulties exhibited depression. The international students who went through financial problems were two times more likely to suffer from depression (OR = 2.38; p-value < 0.01). CONCLUSION: This study tried to highlight the struggles faced by international students in Bangladesh studying dentistry. It is evident from the findings that several factors influence students' mental well-being during demanding dental education years

Phage φAB6-Borne Depolymerase Combats Acinetobacter baumannii Biofilm Formation and Infection

Biofilm formation is one of the main causes of increased antibiotic resistance in Acinetobacter baumannii infections. Bacteriophages and their derivatives, such as tail proteins with depolymerase activity, have shown considerable potential as antibacterial or antivirulence agents against bacterial infections. Here, we gained insights into the activity of a capsular polysaccharide (CPS) depolymerase, derived from the tailspike protein (TSP) of φAB6 phage, to degrade A. baumannii biofilm in vitro. Recombinant TSP showed enzymatic activity and was able to significantly inhibit biofilm formation and degrade formed biofilms; as low as 0.78 ng, the inhibition zone can still be formed on the bacterial lawn. Additionally, TSP inhibited the colonization of A. baumannii on the surface of Foley catheter sections, indicating that it can be used to prevent the adhesion of A. baumannii to medical device surfaces. Transmission and scanning electron microscopy demonstrated membrane leakage of bacterial cells treated with TSP, resulting in cell death. The therapeutic effect of TSP in zebrafish was also evaluated and the results showed that the survival rate was significantly improved (80%) compared with that of the untreated control group (10%). Altogether, we show that TSP derived from φAB6 is expected to become a new antibiotic against multi-drug resistant A. baumannii and a biocontrol agent that prevents the formation of biofilms on medical devices

Analyse der elektrischen Felder von Blitzentladungen in gleichen und unterschiedlichen Kanälen

Abweichender Titel nach Übersetzung der Verfasserin/des VerfassersDas Phänomen „Gewitter und Blitze“ hatte Menschen immer beschäftigt. Neben menschlichem und tierischem Leben gehen auch wirtschaftliche Schäden wie Missernten, Hausund Feuerbrände auf die Rechnung von Blitzen. Die elektromagnetischen Felder, welche von Blitzströmen hervorgerufen werden, erzeugen transiente Fehler in Hochspannungsleitungen und in manchen Fällen führen sie auch zum Ausfall von Hochspannungsnetzen. Aufgrund des großen Umfangs der Kumulonimbus-Wolke von ca. 10 bis 20 km ist es weder leicht, den Einschlagort eines Blitzes genau vorherzusagen, noch die ganze Fläche mit einem Blitzableiter zu schützen. Daher ist es wichtig, die Parameter, die einen Blitzeinschlag bedingen genau zu erforschen. Umso mehr Blitzparameter wir kennen, desto effizienter können wir uns vor Blitzen schützen und das Ausmaß des Schadens verringern. Verschiedene Arten von Blitzen und deren Auftreten zu bestimmten Orten und Jahreszeiten, sowie deren Ursachen, werden von Blitzforschungsinstituten weltweit erforscht. Neben der Blitz-Charakteristik sind auch Faktoren wie Blitzstrom-Parameter, elektrische und elektromagnetische Felder sowie Orte mit hoher Blitzdichte von Forschungsinteresse. Die Untersuchung der Verteilung von Blitzdichten über unterschiedlichen Gebieten (Wohngebiete, Berge, Täler, Wald, Ackerland, etc.) und Blitzschlag an Windturbinen sind ebenso bedeutsam für verschiedenen Anwendungen, wie die Risikoanalyse, Klimaforschung, etc. So hat das Blitzortungssystem ALDIS in Österreich einige Orte mit hoher Blitzdichte aufgedeckt. Außerdem, stellte ALDIS fest, dass Berge und hohe Türme einen Trigger-Effekt für Blitze haben. Nieder gelegene Gebiete weisen hingegen wesentlich geringere Effekte auf. In dieser Masterthesis wird die Hypothese untersucht, dass elektrische Felder von Hauptund Folgeblitzen in dem gleichen Kanal eines negativen Wolke-Erde Blitzes einander mehr ähneln als die Hauptund Folgeblitze vom benachbarten Kanal. Es wurde ein Excel Datenblatt mit elektrischen Felddaten von 74 Blitzen, die insgesamt 319 Hauptund Folgeblitze enthalten, zur Verfügung gestellt. Die Videoaufzeichnungen von diesen Blitzen wurden ebenso bereitgestellt. Das Excel Datenblatt diente der schnellen Orientierung und als Referenz während der Analyse der Blitze. Für die Aufbereitung von Blitzdaten und die Anwendung von statistischen Methoden auf die Blitzdaten wurden Skriptprogramme in der Analysesoftware SCILAB implementiert. Um die Präzession der implementierten Funktionen zu überprüfen, wurden danach die elektrischen Felder der Blitze aus der implementierten Funktion geplottet und mit den, vom DataViewer geplotteten Diagrammen, verglichen. Da die elektrischen Felder mancher Blitze den Kriterien unserer Auswertungsmethodik nicht entsprachen, wurden diese verworfen. Die Felddaten wurden mittels Chi Quadrat und Kreuzkorrelation ausgewertet. Dabei wurden sowohl die Hauptblitze der benachbarten Kanäle desselben Blitzes miteinander als auch die Folgeblitze von benachbarten Kanälen desselben Blitzes miteinander vergleichen. Darüber hinaus wurden die Hauptblitze eines Blitzkanals mit den Folgeblitzen desselben Kanals miteinander und die Folgeblitze desselben Kanals miteinander verglichen. Schließlich wurden Mittelwerte von den Ergebnissen aus Chi Quadrat und Kreuzkorrelation gebildet und mit der Hypothese dieser Diplomarbeit verglichen.The phenomenon of lightning and thunder has drawn the attention of human beings for billions of years. Besides the loss of human and animal lives, also economic damages like crop failure, house and forest fires are caused by lightning. Further, the electromagnetic field generated by the lightning current frequently causes transient faults and blackouts in power transmission grids. Because of the large horizontal extent of a cumulonimbus cloud, which ranges from 10 to 20 km, it is not easy to predict the striking point precisely and it is not possible to prevent the whole area from being struck by lightning using a lightning rod. The more lightning parameters we understand, the more efficiently we can take precautions against lightning damages. The lightning research institutes all over the world investigate the ratio of cloud to cloud (CC) and cloud to ground (CG) flashes, the dependence of lightning on the season, location and storm type, etc. In addition to the characteristics of different kinds of flashes, other factors that are associated with flashes like lightning current parameters, electric and electromagnetic fields generated by a lightning stroke or spots with high flash density are also of interest. Investigations about the distribution of the lightning density over a large area, lightning strikes in an elevated terrain or to the wind turbine are also significant for several applications like risk analysis, evaluating the performance of lightning detection systems or climate studies. Austrian Lightning Detection and Information System (ALDIS) has discovered spots with significant high flash density in Austria. ALDIS noted that tall objects on mountains have a triggering effect to flashes. Flashes to the tower have significantly higher stroke numbers than flashes to the ground in the vicinity of the tower. In this master thesis, the hypothesis that the electric fields of the first and subsequent strokes of the same channel of a negative CG flash are more similar compared to different channels will be examined. 74 flashes containing 319 strokes in form of binary and video files are provided for the evaluation. These files contain the records of the electric fields and the video of the corresponding strokes. An Excel data sheet containing detailed information about the recorded flashes is provided. This data sheet enables a faster orientation of the flashes and is used as a reference during the analysis of the flashes. For processing and applying statistics to the flashes, scripts in an analysis software called SCILAB are implemented. Subsequently, in order to examine the scripts, the waveforms of each stroke are plotted both, by means of these scripts and by DataViewer. As strokes of some flashes do not coincide with the criteria of the evaluation method, they are discarded and not taken into account in the evaluation. The flashes were evaluated with the help of the chi squares and cross correlation. A comparison between the first stroke versus the first stroke, subsequent versus subsequent strokes of different GSPs of the same flash, the first stroke versus subsequent stroke of the same channel (GPS) and subsequent stroke versus subsequent stroke of the same channel is carried out. Finally, the mean value of the results of the comparisons of these groups are calculated and compared to the hypothesis of this masters thesis.5

Spread of COVID-19 and citizens’ behaviour: a comparison of importance-compliance analyses among Bangladeshis and Malaysians

Majority of the countries in the world are grappling with the onslaught of COVID-19 by engaging in various measures to safeguard the lives of citizens of their country. On this backdrop, the present research aims at identifying the attributes that governments need to pay increased attention. The perception data was collected from citizens of two countries i.e., Bangladeshis (n=102) and Malaysians (n=97). The Importance Compliance Analysis (ICA) was applied on 29 attributes for the two countries’ citizens and a comparison was made on the findings. Apart from ICA, Paired as well as Independent Sample t-tests were performed on the data collected. According to the findings (which are applicable for both countries) the respective government should take measures so that their citizens strictly adhere the recommended attributes. The study findings may also help other countries as well in limiting the spread of COVID-19

Evaluation of sedative and anxiolytic activities of methanol extract of leaves of Persicaria hydropiper in mice

Abstract Background Persicaria hydropiper Linn. (Family: Polygonaceae), it grows in damp places and the bank of rivers, canals, lakes, and roadsides of Bangladesh. The leaves of the plant used in traditional medicine to treat insomnia, depression, and neurodegenerative diseases. The objective of this study is to investigate the sedative and anxiolytic activities of the methanol extract of leaves of Persicaria hydropiper (MEPH). Methods The sedative effect of the P. hydropiper at the doses of 50, 200, 350, and 500 mg/kg evaluated using the open field, hole cross, rota-rod and thiopental sodium-induced sleeping time test in mice. The anxiolytic activity evaluated using the elevated-plus maze, light-dark box, hole-board and marble-burying test. Sedative and anxiolytic activities compared to diazepam, a positive control. The acute toxicity test also assessed. Results The neuropharmacological activity of both open field and hole cross tests significant (p < 0.001) decrease the number of (square and hole) crosses by mice compare to control group. The rota-rod test to evaluate the motor coordination or muscle relaxant significantly (p < 0.001) increases the number of falling whereas decrease performance time from the rotating rod. In thiopental sodium-induced sleeping test, MEPH causes a decrease in the sleep latency time and significantly (p < 0.001) increase the duration of sleeping time. In the elevated plus-maze test, the different parameters (the time spent and the number of entries in open arms; the time spent and the number of entries in close arms) observed. Treatment with MEPH significant (p < 0.001) increase the time spent and the number of entries in open arms comparable to control group. In respect of the light-dark box test, several (latency times, the number of transitions, the time spent in the light and dark compartment) parameters also observed. Mice treated with MEPH significant (p < 0.001) increase the time spent in the light compartment compared to control group. The hole-board tests, MEPH significant (p < 0.001) decrease the number of head dips, as well as the number of marbles burying, was significant (p < 0.001) decrease in the marble-burying test showing anxiolytic activity. Conclusion The results indicate that MEPH has sedative and anxiolytic activities, supporting its uses in traditional medicine. Further studies of the isolation of the active components of P. hydropiper and its mechanism of action study strongly recommended before the application in human