Dynamics and Dynamical Systems Commons^™

Voltage-Related Power Quality Issues And Impacts On Distribution Networks With Sensitive Loads - A Review, Godwin Elinazi Mnkeni, Jackson Justo, Aviti Thadei Mushi, Bakari M. M. Mwinyiwiwa

Tanzania Journal of Engineering and Technology (TJET)

Voltage disturbances are the most important power quality (PQ) complications that customers and power utilities face in this smart era. The growing adoption of sophisticated electronic equipment and integration of renewable energy sources (RES) into power grids has increased the susceptibility of power distribution networks (PDNs) to voltage sags, swells, interruptions, flicker, and voltage imbalance. These disturbances, mainly caused by upstream faults, switching operations, and RES integration, compromise voltage PQ and system reliability. Consequently, they accelerate equipment degradation, increase electronic waste (e-waste), raise reactive power demand and maintenance costs, increase power losses, and impose substantial economic losses on customers and …

Physicochemical Properties And Chemical Compositions Of Cashew Nut Shell Liquid Extracted With Carbon Dioxide–Expanded Hexane, Neema Msuya, Joseph Yn Philip, Frank Jacob, Kando K. Janga

Tanzania Journal of Engineering and Technology (TJET)

Cashew nut shell liquid (CNSL) is a mixture of phenolic compounds that can effectively replace commercially available phenols in various applications. This study investigated the physicochemical properties and chemical composition of CNSL extracted using CO₂–expanded hexane (CXH) and compared to the traditional Soxhlet extraction method. Steamed cashew nut shells (sCNS) were used in both cases.  The CXH was carried under varying CO₂-mole fractions (0.468-0.892) and temperatures (20-36 °C) whereas Soxhlet extraction was performed at atmospheric pressure and hexane boiling point. Response Surface Methodology (RSM) with Central Composite Face-Centred Design (CCFD) was employed to evaluate the effect …

Energy Optimal Coverage Motion Trajectory Generation Using A Fourth-Order Motion Profile, Mathias Halinga

Tanzania Journal of Engineering and Technology (TJET)

Industrial machines are widely used in manufacturing sector to manufacture several products to meet customer demands. Most of these industries runs all the time throughout a day leading to high operating cost. To cut costs and satisfy customer demand for precise products, industrial machines’ motion generation is important in improving machine motion precision while using less energy. This study presents a coverage motion energy optimization which is generated by linear interpolation of each segment described by the fourth-order motion profile. The phase changes in the profile are attained with continuity of machine kinematic limits jerk, acceleration, and velocity, which are …

Modeling Of Carbonization And Absorption Processes In Soda Ash Production, Nadirbek Rustambekovich Yusupbekov, Djalolitdin Paxritdinovich Mukhitdinov, Fatima Faxritdinovna Iskhakova

Chemical Technology, Control and Management

The article considers the problem of modeling the ammonia-soda process of soda ash production and presents the chemistry of sodium bicarbonate (NaHCO₃) formation. The equation of the kinetics of the reaction, used as a model of the carbonation process, is derived from a system of equations and its computer model is compiled. The system of differential equations reflecting the kinetics of the process was solved in the Mathcad package. The result of the modeling is presented. Based on the experimental data, the dependence of the absorption column performance on temperature and the dependence reflecting the optimal value of the absorption …

Algorithms For Making Control Systems Based On Neural Network Technology To Automate Dynamic Plants, Jasur Sevinov, Abdishukurov Maqsudovich Shavkat

Chemical Technology, Control and Management

This paper examines the stages of multilayer neural network technology for the control and identification of dynamic systems. It is seen many ways to use multilayer neural networks in control systems. Neural controllers are based on several models and algorithms. Examples of such algorithms include the predictive model-based control algorithm, the Narma-L2 control algorithm, and the benchmark model-based control algorithm. These controllers illustrate various general ways to use multilayer neural networks in control systems. Common, standard linear control architectures have been proposed for many neural controllers.

Collision Dynamics Of Compound Droplets In Microchannels: A Combined Numerical And Data-Driven Study, S M Abdullah Al Mamun

Dissertations

Understanding and predicting the hydrodynamic interactions of micron-scale droplets is crucial in a wide range of industrial and real-life applications, including microfluidics, pharmaceutics, drug delivery, food science, and enhanced oil recovery. These multi-phase and multi-scale phenomena are further complicated by the presence of core droplets of an immiscible fluid within shell droplets, known as compound droplets. The collisions and interactions of droplets in emulsions are influenced by various physical and geometric parameters, leading to distinct rheological and dynamic responses. This research employs numerical methods for a systematic parametric study of both simple and compound droplet pair collisions under confined shear …

Capacitive Sensors With Ultra-Small Capacitance For Smart Measurement And Control Systems, Rustam Baratov, Farrux Jabbor O'G'Li Ko'charov

Chemical Technology, Control and Management

This article discusses methods of low capacitance measurement of capacitive sensors. The results of the study of the amplitude-frequency (AF) and phase-frequency (PF) response of measurement circuits of capacitive sensors for low capacitances measurement, consisting of RC - differentiating elements are presented. The input and output parameters of the differentiating circuit and the complex transfer function are analyzed. The research results show that low capacitances measurement by measuring the rectangular pulses duration is the most effective measurement method.

Analysis Of The Factors Affecting The Oil Recovery From Oilseeds In A Multistage Crosscurrent Leaching Process, Samuel V. Manyele

Tanzania Journal of Engineering and Technology (TJET)

The analysis of the total oil recovery from oilseeds in a multi-stage crosscurrent leaching process is presented. The model created using mass balance equations for three stages was used to analyze the factors affecting total oil recovery, To. The key performance factors (raw meal feed flow rate, solvent feed flow rate in each stage, solvent distribution factor for each stage, percent oil in the raw meal (Poil), solids to solution ratio in the underflow (N), solvent to solids ratio (SSR), solvent to oil ratio (SOR) and wash ratio (WR) were varied while assessing To. While SSRi and SORi ranged from …

Development And Testing Of Small-Scale Flash Dryer For Maize Bran, Eden Ngowi

Tanzania Journal of Engineering and Technology (TJET)

Sun drying is the most common technique used to dry various food products due to its economic convenience. However, it is not effective owing to its unreliable nature leading to microbial deterioration and aflatoxin contamination of food. In Tanzania, about 1.3 million tonnes of maize bran are at risk of deterioration annually due to improper drying. The aim of this study was to design, fabricate and test an efficient small-scale flash dryer for maize bran. Using principles of material and energy balance, a small-scale flash dryer with a throughput of 500 kg of dry product per hour was designed resulting …

Enhanced Post Deposition Annealing Conditions On The Fabrication Of High Quality Thermochromic Vanadium Dioxide Films, Nuru R. Mlyuka

Tanzania Journal of Engineering and Technology (TJET)

Sputter deposition of thermochromic VO2 thin films for smart window applications has been faced with several challenges including the need for high deposition temperature, extremely precise and narrow range of oxygen/argon flow ratio and target poisoning during sputtering. Deposition of VO2 at room temperature without oxygen followed by post-deposition annealing has been cited as one of the potential mitigations to the challenge. In this study, the effects of post-deposition annealing conditions on the structural, electrical and optical properties of VO2 thin films are reported. The films were prepared on soda lime glass substrates using DC magnetron sputtering of metallic vanadium …

Production Of Biofertilizer From Fruit And Garden Waste, Neema Msuya

Tanzania Journal of Engineering and Technology (TJET)

The project focused on the production of bio-fertilizer from fruit and garden waste, with a specific emphasis on utilizing pineapple tops in the composting process. The objective was to produce and assess the properties of the bio fertilizer obtained from this process and evaluate its potential application in agriculture. In this study, the composting process was done in a 0.7 m long, 0.85 wide and 1.1 m high vessel, and 0.238 m3 pineapple top wastes, resulting in 0.35 m3 of biofertilizer. The bio fertilizer produced exhibited favorable characteristics, including a moisture content of 36%, pH of 7.1, and a total …

Assessment Of Risk Factors Related To Body Pain Complaints In Tanzania Construction Industry, Fatma K. Mohamed

Tanzania Journal of Engineering and Technology (TJET)

The construction industry is associated with risks that can result in musculoskeletal diseases. Although young male workers who are presumed to be healthy dominate the industry in Tanzania, body pain complaints have been widely reported. The aim of this study is to assess the prevalence and causes of body pains in workers. A cross-sectional study involving 396 workers was conducted. A chi square test was used for testing association of independent categorical variables and binary logistic regression analysis was used to determine predictors for body pain complaints. The results show that all study participants complained of at least one form …

Nanoscale Modeling Of Membrane Systems Under Mechanical Deformation In Traumatic Brain Injury Using Molecular Dynamics, Anh Thi Ngoc Vo

Theses and Dissertations

Neuronal membrane disruption and mechanoporation are nanoscale damage mechanisms that critically affect brain cell viability during traumatic brain injury (TBI). These nanoscale cellular impairments are elusive in experiments and necessitate in silico approaches such as molecular dynamics (MD) simulations. Implementing MD, this research aims to investigate the effects of different key factors related to membrane deformation and damage, including force field resolutions, lipid compositions, and loading conditions.

To examine the impact of force field resolution, MD deformation simulations were conducted on 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) lipid bilayer membranes, using all-atom (AA), united-atom (UA), and coarse-grained Martini (CG-M) force fields. The mechanical responses …

Study Of Thermoelectric And Lattice Dynamics Properties Of 2d Layered Mx (M = Sn, Pb; X = S, Se, Te) And Zrs2 Compounds Using First-Principles Approach, Abhiyan Pandit

Graduate Theses and Dissertations

The aim of this dissertation is the investigation of thermoelectric and lattice dynamics properties of two-dimensional (2D) MX (M = Sn, Pb; X = S, Se, Te) and ZrS2 compounds based on the first-principles density functional theory. The dimensionality reduction (e.g., using 2D structure) of bulk materials is found to have enhanced thermoelectric efficiency. This enhancement is attributed to the increase of the Seebeck coefficient as a result of higher electronic density of states near the Fermi level in low-dimensional materials. In addition, lowering the dimensionality increases phonon scattering near interfaces and surfaces in 2D materials, which leads to a …

Design And Analysis Of Marangoni-Driven Robotic Surfers, Mitchel L. Timm

Dissertations, Master's Theses and Master's Reports

We designed and experimentally studied the dynamics of two robotic systems that surf along the water-air interface. The robots were self-propelled by means of creating and maintaining a surface tension gradient resulting from an asymmetric release of isopropyl alcohol (IPA). The imbalance in the distribution of surface tension surrounding the robots generates a propulsive force commonly referred to as Marangoni propulsion. First, we considered a single surfer, which was custom-made with novel control mechanisms that allow for both forward motion and steering to be remotely adjusted solely through the manipulation of local surface stresses. We analyzed the performance of this …

Fingering Behavior Of Flame Spread Over Solid Combustibles, Tsuneyoshi Matsuoka, Kentaro Nakashima, Takuma Kajimoto, Akihiro Yoshimasa, Yuji Nakamura

Progress in Scale Modeling, an International Journal

In this study, the fingering pattern formation and the following flamelet spreading over three different kinds of thick combustibles, i.e., Poly methacrylate (PMMA), Poly ethylene (PE) and Poly carbonate (PC) were observed and the effective Lewis number correlation was validated. Experiments were performed with a narrow channel apparatus. In addition to the kinds of solid fuel materials, the channel height and the oxidizer velocity were varied as experimental parameters. An image analysis method was developed to quantify the number, diameter and spread rate of the flamelets. Replacing the fuel thickness into the thermal thickness, the effective Lewis number which is …

Development Of Light Actuated Chemical Delivery Platform On A 2-D Array Of Micropore Structure, Hojjat Rostami Azmand, Hojjat Rostami Azmand

Dissertations and Theses

Localized chemical delivery plays an essential role in the fundamental information transfers within biological systems. Thus, the ability to mimic the natural chemical signal modulation would provide significant contributions to understand the functional signaling pathway of biological cells and develop new prosthetic devices for neurological disorders. In this paper, we demonstrate a light-controlled hydrogel platform that can be used for localized chemical delivery in a high spatial resolution. By utilizing the photothermal behavior of graphene-hydrogel composites confined within micron-sized fluidic channels, patterned light illumination creates the parallel and independent actuation of chemical release in a group of fluidic ports. The …

Adsorption And Reconfiguration Of Amphiphiles At Silica-Water Interfaces: Role Of Electrostatic Interactions, Van Der Waals Forces And Hydrogen Bonds, Yao Wu

LSU Doctoral Dissertations

The ability to explore and predict metastable structures of hybrid self-assemblies is of central importance for the next generation of advanced materials with novel properties. As compared to their thermodynamically stable forms, the kinetically stabilized materials show improved functionality potentially over their stable counterparts. The self-assembly processes usually originate from weak intermolecular interactions, involving a dynamic competition between attractive and repulsive interactions. These weak forces, including van der Waals (vdW), electrostatic interaction and the hydrogen bonding (H-bonding), can be tuned by external stimuli, e.g., confinement, temperature and ionization, and consequently driving hybrid materials into different configurations. It is challenging to …

Capillary Forces And Wetting Dynamics By Diffuse-Interface Modeling, Fanny Thomas

Dissertations and Theses

Wetting phenomena underlie many natural and industrial processes, from the proper functioning of the lungs to the thin coating of surfaces. The three-phase interactions involved at microscopic scales play a critical role. Adding solid particles to an emulsion, for example, can drastically change the flow behavior due to capillary bridging between the particles. The study of these three-phase systems is especially relevant to the petroleum industry, where gas hydrates forming large clusters in subsea pipelines during crude oil transportation is a major concern. The dynamics of such systems is also of great interest from a fundamental perspective. Indeed describing non-equilibrium …

The Potentials Of Faecal Sludge Treatment Using Local Conditioners In Tanzania: A Review, Doglas Benjamin1

Tanzania Journal of Engineering and Technology (TJET)

Worldwide, every day human beings generate millions of tons of Faecal Sludge (FS), which is rich in water, nutrients, energy, and organic compounds. Yet FS is not being managed in a way that permits us to derive value from its reuse, while at the same time, millions of farmers struggle with depleted soils and lack of water. In most of the developing countries, energy for cooking is mainly derived from cutting of trees, either as wood or charcoal. Resource recovery and reuse from FS can create livelihoods, enhance food security, support green economies, reduce waste and contribute to cost recovery …

Design And Commissioning Of A Community Scale Solar Powered Membrane-Based Water Purification System In Haiti, Shavin Pinto, Yung Wong, Kyle Fennesy, Yan Tang, Marc Compere

Publications

This paper presents the design and commissioning of a solar powered water purification system at the Ryan Epps Home for Children (REHC) in Michaud, Haiti. This system supplies clean drinking water to the 200 children who live and go to school at REHC and also to the community in the form of a micro-business. This micro-business is the mechanism for income generation for sustainable system operation. The purifier uses a three stage filtration system with a disc-type sediment filter, a 0.1 micron ultrafiltration membrane, and an ultraviolet light for disinfection. The backwash cycle extends the life of the ultrafiltration membrane …

Socio-Economic Impacts Of Computer Viruses In Tanzania, M Victor

Tanzania Journal of Engineering and Technology (TJET)

This paper reports on a research project conducted with an objective of identifying and assessing various approaches used by different computer users (Management, System Administrators and end users) in Tanzania to combat computer viruses (CVs), and to assess users' awareness level on CVs. Specifically, the study aimed at assessing the awareness level on CVs to the Tanzanian business community; analyze the socio -economic impact caused by CVs in Tanzania and; assess existing methods, capacity and limitations on controlling CVs in Tanzania. Data was collected using both questionnaires and interview from financial institutions such as NBC and BOT, and telecommunications sector …

Review Of The Product Development Process And Information Flow In The Manufacturing Industry: Problems And A Possible Wav Forward, E Opiyo

Tanzania Journal of Engineering and Technology (TJET)

No abstract provided.

Application Of Vibrational Techniques In Determination Of Dynamic Properties Of Agricultural Products-State Of The Arton Of Vibrational Techniques In Determination Of Dynamic Properties Of Agricultural Products-State Of The Art, Silas Kajuna

Tanzania Journal of Engineering and Technology (TJET)

Vibration is one of the techniques employed in the determination of dynamic properties of fruits and vegetables. It entails generation of a mechanical or acoustic vibrational signal which is propagated through the flesh of the agricultural material. A transducer is either attached or held close to the specimen to monitor the propagation of the signal through the specimen. The manner in which the signal is transmitted through the material is analyzed, and the dynamic properties of the specimen which relate to its firmness or its internal being are derived. The technique has been around for the past 30 years or …

Effects Of Radiative Interactions In Molecular Gases Under Local And Nonlocal Thermodynamic Equilibrium Conditions, Manoj Kumar Jha

Mechanical & Aerospace Engineering Theses & Dissertations

Basic formulations, analyses, and numerical procedures are presented to investigate radiative heat interactions in diatomic and polyatomic gases under local and nonlocal thermodynamic equilibrium conditions. Essential governing equations are presented for both gray and nongray gases. Information is provided on absorption models, relaxation times, and transfer equations. Radiative flux equations are developed which are applicable under local and nonlocal thermodynamic equilibrium conditions.

The problem is solved for fully developed laminar incompressible flows between two parallel plates under the boundary condition of a uniform surface heat flux. For specific applications, three diatomic and three polyatomic gases are considered. The results are …