HEADSPACE GAS CHROMATOGRAPHY FOR THE DETERMINATION OF RESIDUAL SOLVENTS IN METFORMIN HYDROCHLORIDE AND HYDROCHLOROTHIAZIDE

An accurate analytical method was developed using headspace gas chromatography for the determination of residual solvents in metformin hydrochloride and hydrochlorothiazide. The residual solvent was studied with the help of gas chromatography (Shimadzu 2014 model) combined with Teledyne Tekmar headspace and GC solution software. The residual solvents were separated using DB-WAX column 30-meter-long, 0.32mm internal diameter for metformin hydrochloride and BP624 column 30-meter-long, 0.53 mm internal diameter for hydrochlorothiazide. The limit of detection and limit of quantitation of dimethylacetamide, methanol and benzene were 17.00, 10.93, 0.18 and 51.92, 33.13, 0.57 ppm respectively for metformin hydrochloride and in case of hydrochlorothiazide, the values were 3.40& 1.30 ppm and 10.15 & 4.00 ppm for methanol and methyl isobutyl ketone respectively. The method was validated according to international conference on harmonization guideline in terms of specificity, linearity, precision, accuracy and robustness

Piezoelectric Transducer as an Energy Harvester: A Review

Over the years, energy harvesting technologies have been used in various self-powered systems. These technologies have several methods of application depending on their usage. Renewable energy is one of the types of energy harvesting technologies where energy is generated from naturally replenished sources. One of the energy harvesting methods that is commonly used is piezoelectric transducers. Piezoelectric materials are groups of elements that can be used to generate electricity when mechanical energy is applied. When external mechanical stress is applied, the inner lattice is deformed, resulting in the separation of the positive and negative centers of the molecule and thus the generation of a small dipole. Therefore, this paper aims to discuss the output of the piezoelectric transducer by reviewing it depending on two different material types and in other energy harvesting structures. Furthermore, a comparison was made in order to compare the power output of the two materials. Similarly, the most used piezoelectric transducer structures for power harvesting applications were revised. In addition, the parameters that affect the value of the generated power output were discussed using the figures of merit (FOM) concept. Moreover, the according to the FOM concepts, when stress is applied, the electrical energy extracted from a piezoelectric energy harvesting material is determined by the change in stored electrical energy within a piezoelectric material. The figures of merit (FOM) depend on the piezoelectric strain and its permittivity. The piezoelectric strain directly relates to FOM, while the permittivity has an inverse relationship with FOM. Thus, the highest strain constant and low permittivity material will provide the highest energy output. Additionally, lead-based (PZT) material has a strain coefficient d33 equal to 390 Coul/Nx10-12, and permittivity value ranging from 1000 to 3500 and can generate power output that is equal to 52mW at 100Hz, which is higher than the output of the lead-free-based material Barium Titanate (BaTiO3). The output of piezoelectric also depends on the piezoelectric transducer’s structure. The circular diaphragm’s power output is greater than the bimorph cantilever’s power output due to the presence of a proof mass in the center of the diaphragm that provides prestress to the piezoelectric which improves the low-frequency performance of the energy harvester

MODELING AND NEURAL CONTROL OF QUADROTOR HELICOPTER

Quadrotor Helicopter or simply quadrotor is rotorcraft that has four lift-generating propellers. Two of the propellers spin clock wise and the other two counter-clockwise. Control of the machine can be achieved by varying relative speed of the propellers. Quadrotor concept is not new, however the modern quadrotors are mostly unmanned. Advancement in miniaturized IMU technology, availability of high speed brushless motors and high power to weight ratio Li-Polymer battery technology, quadrotors can now be successfully designed and fabricated. This paper proposes a mathematical model of quadrotor dynamics and a control scheme based on Direct Inverse Neural Control. In modeling A simplified approach is adopted where the gyroscopic effect and air friction on frame of machine has been neglected, resulting in a simplified model, which is useful for designing a controller to stabilize the plant in hover state. Proposed model is non-linear since the rotor dynamics are a function of square of motor inputs. The neural network based controller, exploits the multiple layer perceptron trained by the back propagation algorithm. Direct inverse control scheme uses the idea of canceling out the dynamics of a plant by training the controller to approximate the inverse of the plant. This scheme however requires the plant to have a stable inverse

CREATING AND MEASURING RELATIVE HARDNESS FEELING VIA MASTER-SLAVE HAPTIC GRIPPER

This paper discusses the completed work in designing a master-slave haptic gripper system aiming to recreate the relative hardness feeling of different real test objects at the slave gripper to the user at the master gripper. The main contribution of this paper is to prove the feasibility of recreating the relative hardness feeling of real objects to the users as oppose to recreating the hardness feeling of virtual objects which has been proven to be feasible for quite some time. Three experiments involving twenty test subjects and fifteen pairs of test object combinations are conducted to evaluate the performance of the master-slave haptic gripper system. Experiments show that users at the master gripper end are able to differentiate the relative hardness level of the test objects handled by the slave gripper. The secondary contribution of this paper is the introduction of haptic index defined as a set of numerical value that describe the otherwise immeasurable subjective relative hardness level of an object felt by human. The proposed haptic index can contribute towards designing better robots and controllers that can feel the relative hardness of objects like in the human world

UNIFIED POWER FLOW CONTROLLER CONTROL STRATEGIES for POWER FLOW

In order to address power flow control issues, this study introduces the use of Unified Power Flow Controller (UPFC) models. These models are based on regulating the variables influencing the transmission line’s power flow, and they are capable of controlling the bus voltage, the line’s actual and reactive power, all at once and independently. The idea behind the UPFC technique proposed in this paper is to provide the unique functional capability of independently controlling both the real and reactive power flow in the line. The in-phase component of the series injected voltage dominates the reactive power while the quadrature component affects the real power. A conventional controlling steady-state analysis and dynamic stability analysis of the power system is developed based on the UPFC model. UPFC provides real-time controlling of all or any combination of the power system parameters which determine the transmittable power. UPFC can force and maintain strategically chosen values of the active power and the reactive power at a given point of the line by PI control

SOFT PRODUCTION OF PHY MESON IN PHOTON PROTON INTERACTION

In the present model the photoproduction of the ∅ meson cross section is calculated. The contribution from soft pomeron exchange is calculated using DL model. It is found that this model is over-estimated the data. A mass correction factor related to the masses of p and mesons is used to normalize the DL model. The hard pomeron contribution is also calculated using The pQCD model. A reasonable agreement between the model and the data is obtained.

Experimental Study of Micro Thermoelectric Cooler Module

Micro thermoelectric cooler (μTEC) modules have recently attracted significant attention due to their compact size, effective heat dissipation, and rapid thermal response. These characteristics make them highly suitable for applications in electronics, telecommunications, and healthcare. The present study focuses on evaluating the cooling performance of a μTEC module under varying operating conditions. A comprehensive experimental setup was developed to measure critical parameters such as temperature difference, cooling capacity, and coefficient of performance (COP). Experimental results were compared with theoretical predictions, revealing a strong correlation, particularly at lower temperature differences and moderate current levels. However, deviations were observed at higher currents, primarily attributed to increased Joule heating and contact resistance. Overall, the agreement between experimental data and the theoretical model supports its validity while also highlighting areas for potential refinement. The findings contribute to a deeper understanding of μTEC efficiency and support future enhancements in thermoelectric cooling system design

HEAT SAVING IN EVAPORATIVE CRYSTALLIZATION BY INTRODUCING A HEAT PUMP

Particle Imaging Velocimetry (PIV) has been recognized as an essential and very useful technique for analyzing two or three- dimensional complex flow fields and two-phase fluid flows. PIV techniques promise to give improved results because they provide a visual solution taking the total field into account. In addition, PIV offers many advantages for the study of fluid flow. PIV is a measuring technique that allows us to capture the flow velocity of whole flow fields in a fraction of a second. Hence, PIV has become more and more popular and it has rapidly spread in the world being recognized as the most advanced flow velocimetry because of its strong merits. Its application ranges have been expanding to measure turbulent flow, multiphase flow, internal flow of fluid machines, bioengineering, medical engineering, environmental engineering, energy engineering, development of new materials, sports science, life science, mechatronics, robotics and so on. Furthermore, PIV has been recognized as a powerful new measuring tool in thermal and fluid engineering fields including multiphase flows. Thus, PIV is a very promising powerful tool in the study of the structure of flows. In this paper, the principles and the typically used methods of PIV measurement are summarized. The classification of PIV methods is also explained

NUMERICAL SOLUTION OF CONVECTION-DIFFUSION EQUATION BY CHEBYSHEV SPECTRAL METHOD VIA LIE GROUP METHOD

The numerical solution of convection-diffusion equation is presented by using Chebyshev spectral method based on El-Gendi method via Lie group analysis. Firstly, we apply Lie symmetry group analysis for the convection-diffusion equation. This method yields convection-diffusion equation to a system of ordinary differential equations (ODEs). Secondly, this system is solved numerically by using Chebyshev spectral method. The numerical results obtained by this way are compared with the exact solution

HEAT DISSIPATION ANALYSIS OF A FIN WITH HEXAGONAL PERFORATIONS OF ITS ONE SIDE PARALLEL TO THE FIN BASE

Finite element method (FEM) is among important numerical techniques used in thermal engineering analyses. Usually elements are sub-divided uniformly in FEM to obtain temperature distribution in a fin or plate. In this paper heat transfer dissipation from a horizontal rectangular fin embedded with hexagonal perforations is computed numerically using one dimensional finite element technique. The orientation of the hexagonal perforations makes two sides of it parallel to the base and tip of the fin. The body of the fin is discretized into the sufficient finite elements. The number of these elements can be altered as required according to the automatic mesh generation. The heat dissipation of the perforated fin is computed and compared with that of the solid one of the same dimensions and same thermal properties. The comparison refers to acceptable results and heat dissipation enhancement due to certain perforation