Modeling of Pressure Retarded Osmosis Using the Q-Electrolattice Equation of State

The mixing of solutions of different salinities occurs in many practical situations. A large-scale example is the mixing of river water with seawater. Such mixing processes have attracted much attention as a potential renewable energy source through a membrane-based process known as pressure-retarded osmosis (PRO). The ultimate goal of PRO units is to convert the energy released by the mixing process into mechanical or electrical power. While many researchers agree that PRO processes based on the salinity difference between freshwater and seawater are unfeasible at current conditions, more study is necessary to assess the feasibility of processes based on streams of higher salinity. One such processes is the energy recovery from desalination units by taking advantage of the mixing of discharged brine and seawater. Another process is the mixing of seawater with high-salinity produced water from oil exploration. This thesis investigates the power that can be harvested from different mixing systems such as freshwater+seawater, brine+seawater, and produced-water+seawater by PRO. To assess the performance of PRO, it is necessary to predict various thermodynamic properties such as Gibbs free energy, osmotic pressure, molar volume, entropy, and enthalpy and to calculate water fluxes across the membrane accurately. The Q-electrolattice equation of state (EOS), which extends a lattice-based fluid model for electrolyte solutions, is adopted to estimate the thermodynamic properties of the electrolyte solutions. However, the behavior of water fluxes through the membrane unit is much complicated due to concentration polarization, fouling of membrane, and reverse salt flux. Recently two very useful equations have been proposed to estimate the water and salt fluxes across the membrane that consider all of them, but the problem is the implementation of these equations into the PRO calculation. Many models have been developed for PRO calculation, which calculates thermodynamic properties, water flux, and power outputs separately even though they are interdependent, thus introducing the possibility of inconsistent results. In addition, quite often, studies on this topic adopt correlations for these various properties and are based on solutions of Na⁺ and Cl¯ ions only while, in practice, the solutions contain many other ions. This work develops a model to estimate the power recovery from the mixing of two solutions of different salinities by incorporating mass flux equations with Q-electrolattice EOS, which is capable of estimating all necessary thermodynamic properties and determining water and salt fluxes and power density simultaneously in a single framework. Initial investigations have been done for the solutions of Na⁺ and Cl¯ ions only. Finally, the developed model is extended to solutions of multiple ions (Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl¯ and SO²¯₄) and to multiple membrane systems

An Analysis of the Potential Applications of Big Data Analytics (BDA) in Supply Chain Management: Emerging Market Perspective

Big Data is defined as the techniques, technologies, systems, practices, methodologies, and applications that analyze critical business data to help an enterprise better understand its business and market and make timely business decisions. Big Data can be utilized to gain critical and fundamental insights towards optimizing the supply chain decisions more effective and efficient. In the recent years, therefore, researchers and practitioners have tried to measure the capabilities of Big Data to optimize Supply Chain Management (SCM) efficiency. This research attempts to provide a clear understanding of Big Data applications on Supply Chain Management in emerging markets, especially in Bangladesh, primarily focusing on four key areas: reducing inventory cost, attaining cost leadership, improving customer service and enhancing speed of delivery. To investigate the potential application of Big Data in supply management, a qualitative research has been conducted. Ten in-depth interviews and a case study have been conducted to collect the relevant information from the supply chain experts of the selected firms. Thematic analysis and Hermeneutic iterative methods of analyses have been used. The results indicate that the supply chain of both physical products and services can be benefited from Big Data analytics. The study also revealed that Big Data can be applied in SCM for operational and development purposes including value discovery, value creation and value capture. This study would help the decision makers and practitioners of Supply Chain Management of diverse fields to adopt Big Data to improve the organizations performance and sustainability. Keywords: Big Data analytics, Supply Chain Management, applications, emerging markets

Comparison of Compressive Strength and Flexural Capacity between Engineered Cementitious Composites (Bendable Concrete) and Conventional Concrete used in Bangladesh

The Engineered Cementitious Composites (ECC) is made of the same ingredients as in regular concrete. The coarse aggregate is replaced with tiny Polyvinyl Alcohol fibres. This structure offers maximum flexibility and it is expected to cost less. It looks exactly like normal concrete, but under excessive strain, the ECC concrete allows, the specially coated network of fibre in the cement to slide within the cement, thus avoiding the inflexibility that causes brittleness and breakage. As this is a special type of concrete there are no defined codes for it, thus for these reasons, the parameters needed are to be obtained using trial and error method. During the composite preparation, sieve analysis was carried out. Composites were reinforced with Polyvinyl Alcohol (PVA) at the following ratios: 0 % (control), 0.5 %, 1 % and 1.5 %. The cylindrical specimens were subjected to compression and the slab specimens were subjected to flexural test using a Universal Testing Machine, while acquiring data with GOM Correlation Software. Test results reveal that fibre ratio 1% is most acceptable for attaining best compressive strength along with high flexural value. Even though 1% fibre content concrete in the flexural strength test showed 33% less strength of what 1.5% fibre content concrete gained, in the long run, for having the highest compressive strength value (almost 62% more than of 0% fibre content concrete and 15% more than of 1.5% fibre content concrete), 1% fibre content concrete is most suited for constructions

Stress and Strain Distributions during Machining of Ti-6Al-4V at Ambient and Cryogenic Temperatures

Dry and liquid nitrogen pre-cooled Ti-6Al-4V samples were machined at a cutting speed of 43.2 m/min and at low (0.1 mm/rev) to high (0.4 mm/rev) feed rates for understanding the effects of temperature and strain rate on chip microstructures. During cryogenic machining, it was observed that between feed rates of 0.10 and 0.30 mm/rev, a 25% pressure reduction on tool occurred. Smaller number of chips and low tool/chip contact time and temperature were observed (compared to dry machining under ambient conditions). An in-situ set-up that consisted of a microscope and a lathe was constructed and helped to propose a novel serrated chip formation mechanism when microstructures (strain localization) and surface roughness were considered. Dimpled fracture surfaces observed in high-speed-machined chips were formed due to stable crack propagation that was also recorded during in-situ machining. An instability criterion was developed that showed easier strain localization within the 0.10-0.30mm/rev feed rate range

Rational Synthesis of Ultra-small and Durable Platinum-based Catalysts for Renewable Energy Applications

Ultrasmall supported platinum nanoparticles (Pt NPs) are often used in two promising renewable energy production technologies – hybrid-sulfur water splitting for actively catalyzing H2SO4 decomposition and in fuel cells for the oxygen reduction reaction (ORR). However, the stability of Pt NPs under reaction conditions is the ultimate challenge for these processes. Two prevalent ways to overcome this challenge are improving stability by anchoring Pt onto a secondary metal or doping heteroatoms into the support. This dissertation covers the rational design, synthesis, and stabilization of Pt-based catalysts in these two ways to achieve durable catalytic performance with desired activity and selectivity. The first vein of this research explores the stabilization of core-shell structured Ir-Pt bimetallic NPs on pre-stabilized titania (TiO2) or boron nitride (BN) support for high-temperature H2SO4 decomposition, particularly SO3 to SO2 decomposition. A series of Ir-Pt catalysts have been synthesized with different Ir loading and evaluated for the selective decomposition of SO3 to SO2 in an extreme (high temperature, highly corrosive) reaction environments. Investigations have revealed that the deactivation of Ir-Pt catalyst on pre-stabilized TiO2 is more dominant than BN, confirmed by X-ray diffraction and catalyst evaluation results. Furthermore, a negligible catalyst deactivation has been obtained for 1\%Pt-7.5\%Ir/BN. Various characterization techniques have been employed to explain this consistent stability. In the second vein of research, the stabilization of Pt NPs by nitrogen-doped carbon has been explored with a combination of high sensitivity X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) with in-situ pretreatment. The high sensitivity XRD instrument has allowed the incredibly observationed the behavior of ultrasmall Pt NPs (about 1 nm), which was previously impossible to observedetect. Furthermore, the XRD results have been clarified the unappreciated trend in the literature of why XRD peaks of ultrasmall Pt NPs often appear shifted to the left. Additionally, using XPS, this work has been corrected a prevalent literature delusion that higher valences of Pt in N-doped carbon result from the formation of Pt-N bond. In the final part of this work, the strong electrostatic interaction (SEA) technique has been explored to synthesize small, uniformly distributed, and highly dispersed Pt NPs on Vulcan XC72R carbon (Pt/C). The SEA method has significantly improved catalyst durability for ORR in proton-exchange membrane fuel cells (PEMFCs) by tuning metal-support interactions, confirmed by a comparative durability study in PEMFCs on various Pt/C catalysts prepared by dry and wet impregnation, polyol, and SEA methods. In addition, a thermal stability test has been performed based on these Pt/C catalysts that have validated the superiority SEA catalyst by demonstrating the metal-support interactions

A Case of Haemorrhagic Herpes Zoster

Background: Varicella-zoster virus (HHV3) is one of the virus in herpes family. Herpes zoster results from the reactivation of varicella-zoster virus in the dorsal root ganglion. This reactivation occurs in immunocompromised conditions such as people with cancer, organ transplant recipients or those receiving chemotherapy, and people with HIV. Old age is also an important risk for the development of herpes zoster. Immunocompromised patients are at increased risk of VZV reactivation because of reduced T cell-mediated immunity. Emotional stress has also been mentioned as an associated factor in people with herpes zoster. The Classic clinical presentation consists of clear vesicular eruptions in dermatomal distribution which are painful. An immunocompromised individual may have frequent attacks of herpes zoster, cutaneous dissemination, organ involvement, and hemorrhagic herpes zoster. Haemorrhagic herpes zoster is an atypical form of herpes zoster develops in patients who are immunosuppressed and people of advanced age who are taking antiplatelets, and anticoagulants, and also in patients with thrombocytopenia due to any cause.  The most common Association of herpes zoster is observed with lymphocytic leukemia and less frequently with myeloid leukemia. Management icludes antiviral therapy along with management of haemorrhagic conditions. Case Report: A nondiabetic male of 60 years attended the medicine outpatients department with complaints of epistaxis for two days. No history of bleeding from other sites was evident. There was no history of trauma or taking of anticoagulants or antiplatelets. No history of fever. The patient was anaemic and an erythematous rash was evident along the right T6 dermatome. He was admitted to the general medicine ward. On the second day of his admission, our patient developed painful haemorrhagic bullous lesions over the right T6 dermatome resembling a bunch of grapes and erythematous popular lesions all over his body (Figure 1). The bullous lesions became larger in size in the subsequent two days of admission. On query, he mentioned that he had suffered from Varicella Zoster in his early childhood. Patients haemoglobin was 10.70 gm/dl, total count of white blood cell (WBC) was 13.20 K/ mm3 (normal value 4.00 – 11.00 K/ mm3), neutrophil and lymphocyte counts were 2.38 K/ mm3 (normal value 2.16 – 6.04 K/ mm3) and 10.38 K/ mm3 (normal value 0.6 – 3.06 K/ mm3) respectively. His platelet count was 5.00 K/ mm3 (normal value 150.00 – 400.00 K/ mm3). The patient denied skin biopsy. A diagnosis of haemorrhagic herpes zoster was made after a dermatology consultation and oral valacyclovir was started along with oral and topical antibiotics and regular dressings. After six units of platelet transfusion patients, the platelet count was raised to 30 K/ mm3. Peripheral blood film was suggestive of acute leukaemia. A bone marrow examination was suggestive of acute myeloid leukaemia. The patient was transferred to the haemato-oncology ward for further planning and management. Conclusion: Haemorrhagic herpes zoster may occur in different clinical conditions and one of them although rare, is acute myeloid leukaemia. Clinical scenario along with bone marrow and blood picture helps to reach a diagnosis in such cases

Comparison of Compressive Strength and Flexural Capacity between Engineered Cementitious Composites (Bendable Concrete) and Conventional Concrete used in Bangladesh

The Engineered Cementitious Composites (ECC) is made of the same ingredients as in regular concrete. The coarse aggregate is replaced with tiny Polyvinyl Alcohol fibres. This structure offers maximum flexibility and it is expected to cost less. It looks exactly like normal concrete, but under excessive strain, the ECC concrete allows, the specially coated network of fibre in the cement to slide within the cement, thus avoiding the inflexibility that causes brittleness and breakage. As this is a special type of concrete there are no defined codes for it, thus for these reasons, the parameters needed are to be obtained using trial and error method. During the composite preparation, sieve analysis was carried out. Composites were reinforced with Polyvinyl Alcohol (PVA) at the following ratios: 0 % (control), 0.5 %, 1 % and 1.5 %. The cylindrical specimens were subjected to compression and the slab specimens were subjected to flexural test using a Universal Testing Machine, while acquiring data with GOM Correlation Software. Test results reveal that fibre ratio 1% is most acceptable for attaining best compressive strength along with high flexural value. Even though 1% fibre content concrete in the flexural strength test showed 33% less strength of what 1.5% fibre content concrete gained, in the long run, for having the highest compressive strength value (almost 62% more than of 0% fibre content concrete and 15% more than of 1.5% fibre content concrete), 1% fibre content concrete is most suited for constructions

Explainable AI in Diagnosing and Anticipating Leukemia Using Transfer Learning Method

This research paper focuses on Acute Lymphoblastic Leukemia (ALL), a form of blood cancer prevalent in children and teenagers, characterized by the rapid proliferation of immature white blood cells (WBCs). These atypical cells can overwhelm healthy cells, leading to severe health consequences. Early and accurate detection of ALL is vital for effective treatment and improving survival rates. Traditional diagnostic methods are time-consuming, costly, and prone to errors. The paper proposes an automated detection approach using computer-aided diagnostic (CAD) models, leveraging deep learning techniques to enhance the accuracy and efficiency of leukemia diagnosis. The study utilizes various transfer learning models like ResNet101V2, VGG19, InceptionV3, and InceptionResNetV2 for classifying ALL. The methodology includes using the Local Interpretable Model-Agnostic Explanations (LIME) for ensuring the validity and reliability of the AI system's predictions. This approach is critical for overcoming the "black box" nature of AI, where decisions made by models are often opaque and unaccountable. The paper highlights that the proposed method using the InceptionV3 model achieved an impressive 98.38% accuracy, outperforming other tested models. The results, verified by the LIME algorithm, showcase the potential of this method in accurately identifying ALL, providing a valuable tool for medical practitioners. The research underscores the impact of explainable artificial intelligence (XAI) in medical diagnostics, paving the way for more transparent and trustworthy AI applications in healthcare

An End-to-End Bitstream Tamper Attack Against Flip-Chip FPGAs

FPGA bitstream encryption and authentication can be defeated by various techniques and it is critical to understand how these vulnerabilities enable extraction and tampering of commercial FPGA bitstreams. We exploit the physical vulnerability of bitstream encryption keys to readout using failure analysis equipment and conduct an end-to-end bitstream tamper attack. Our work underscores the feasibility of supply chain bitstream tampering and the necessity of guarding against such attacks in critical systems