Investigation onto the Effect of Surface Etching using Chemical Etchants on the Dye-Ability of UHMWPE Fibre

Ultra high molecular weight fibre cannot be dyed using conventional dyeing techniques as they are extremely hydrophobic and do not possess any polar groups. Wet etching of the surface was used as the pre-treatment process to improve the dyeability of the Ultrahigh Molecular Weight Polyethylene (UHMWPE) knitted fabric using potassium dichromate and sulphuric acid as etchants. The surface modified fabric was dyed at 130°C using High Temperature (HT) dyeing technique with disperse dye and evaluated in terms of Color Strength (K/S), washing fastness, rubbing fastness, and tenacity. It has been observed that wet etching improved the colour strength substantially with an overall good fastness to washing and rubbing but the tenacity decreased with an increase in etching time.

Exploring Potable Groundwater Sources Surrounding Manchar Lake

This study was carried out to explore the groundwater quality in Manchar Lake's surroundings, (one of Asia's largest lakes in Sindh Province of Pakistan), to discover sites where potable groundwater is available. To achieve this objective, Vertical Electrical Sounding (VES) was employed at 21 sites in shallow depths by adopting Schlumberger electrode array alignment. The maximum distance chosen between current electrodes (A & B) was 300 m, and 20 m was between potential electrodes (M & N). ABEM terrameter SAS 4000 and IX1D resistivity software was used for data collection and interpretation, respectively. The results revealed that except for two sites (13 and 19), all other sites do not have potable groundwater at any depth. At site 13, one out of three layers lies under a high resistivity zone, while at site 19, two out of four layers lie under a high resistivity zone, which indicates the presence of potable water. To verify VES findings, water samples from 5 trial bores made by hand percussion method were collected and analyzed for Electrical Conductivity (EC) and Total Dissolved Solids (TDS), which revealed saline water from all trial bores. To sum up, potable groundwater is not available in the vicinity of Manchar Lake at shallow depths.

Experimental Study on Influence of Methylcellulose on Tensile and Flexural Strength of Normal Strength Ordinary Portland Cement Concrete

Current study explores the possibility of improvement in various categories of concrete’s strengths (including tensile strength, flexural strength etc.) by using methylcellulose as an additive. The effect of methylcellulose on concrete’s compressive strength has also been investigated experimentally. Concrete samples were casted with several methylcellulose to binder ratios varying from 0.002 to 0.01 by weight of cement. Several tests were performed on concrete specimens including concrete cylinder and cube compression tests, split cylinder tests and modulus of rupture tests. Results showed that addition of methylcellulose increased the tensile strength of concrete. Addition of 0.2% of methylcellulose increased the tensile strength of concrete by 16%. This increase in tensile strength reached up to 73% of the control sample on addition of 1% methylcellulose. It was observed that the effect of methylcellulose on compressive strength of concrete depends upon the type of samples being tested (cube or cylinder). The compressive strength of concrete cylinders showed a plateau behavior with peak at 0.4% methylcellulose content with an increase of 18.7%. Effect of methylcellulose on concrete cylinder strength becomes insignificant beyond 0.6%. It was observed that addition of methylcellulose reduces the modulus of rupture values. The reduction in MOR was only 3% at 0.2% methylcellulose content but it grew to 30% at 1% methylcellulose content. The research presents an effective way of increasing tensile strength of concrete but without significant effect on concrete’s compressive strength and modulus of rupture values. These findings can be used to determine optimum content of methylcellulose to achieve desired performance from concrete depending upon the intended use.

Detection and Prevention of Malware in Android Operating System

The Internet is not safe anymore, malware can be discovered anywhere on the Internet. The risk of malware has increased also due to the increasing popularity and use of Smartphones and their underlying cost-free applications. With its great market share, the Android operating system has become a prime target for malware developers. When an Android phone is injected with a malware, it may result in compromising the privacy of the user by stealing sensitive and private information like contacts, ids, passwords, photos, call records, and so on. Compared to any other Android-based application category, games are the most preferred zone for attackers, due to the high interest of users in game applications. When an end user downloads a game, which is injected with malicious code, user data is infected without bringing in the knowledge of the user. Though, there still are not sufficient protection mechanisms or guidelines stated for end user against Android malware, this study offers a novel approach to detect Android malware in order to ensure the safe usage of Android applications. The advantage of this approach is its ability to utilize Android manifest files for the detection of malware. The availability of manifest file in every Android application makes this approach applicable to all Android applications. It can also be considered as a lightweight method for malware detection, and its efficiency is experimentally confirmed by testing and comparing the results of 50 Android games samples. Experiments are carried out using the Android Package Kit (APK) tools, and based on the experiments, different kinds of malware identification and prevention guidelines have been proposed for the safe and secure usage of the Android operating system.

Investigating the Strength and Durability Properties of One Way Slabs Incorporating Marble Dust as Cement Replacement Material

To reduce the environmental pollution caused by cement manufacturing and to save both the economy and resources, it is required to use alternative waste materials of pozzolanic nature to partially replace cement in the construction industry. Among different cement replacement materials being used now-a-days, marble dust is the one on which limited research has been done especially on the performance of structural members like RC slabs. In this paper, marble dust has been used in different ratios as partial replacement of cement in concrete mix. RC one-way slabs as well as plain concrete standard samples were cast to determine their mechanical properties i.e. compressive, tensile and flexural strengths, stiffness, first & ultimate load, crack patterns, modulus of elasticity, maximum deflection and durability etc. It was found that by increasing the dosage of marble dust in plain concrete samples, workability was decreased. Compressive and tensile strengths of concrete increased up to 7.5% replacement but decreased on further replacement. The permeability of concrete decreased with the addition of marble dust up to 10% replacement, then it increased. The behavior of one-way slabs showed an increase in the first crack load and ultimate failure capacity. Moreover, decrease in the deflection of slabs was observed with the increasing replacement of cement with marble dust. The resistance of concrete against corrosion of steel reinforcement also increased due to less migration of chloride ions. Ultrasonic Pulse Velocity (UPV) tests showed improved homogeneity and stiffness of concrete structure with the replacement of cement by marble dust.

GaN Based HEMT Power Amplifier Design with 44.5dBm Output Power Operating at 5-7GHz

The next-generation wireless communication systems including satellite, radar, and mobile communications need application-specific power amplifiers that can operate at very high frequencies and high power with the overall minimum power consumption from the system. To meet such stringent requirements there is a rising interest in amplifier designs based on GaN transistors. This paper presents an improved design of a high power amplifier based on GaN HEMT transistor operating at the frequency band 5GHz – 7GHz with optimized output power level. The presented design is based on a 12 Watt Discrete Power GaN on SiC HEMT from TriQuint. In this manuscript, we have considered the stability of the amplifier for the whole operating frequency band, its input and output matching impedance, gain, and maximum output power. The design of the Radio Frequency (RF) power amplifier and its overall performance are carried out using an advanced design system (ADS). The simulation results of the device stability and the output power level achieved provides a good comparison with the parameters and specifications of the device used. For better correlations in the simulation results and measurements, the accuracy of passive element designs are also considered. The simulation and experiment results show that the designed high power amplifier has achieved an output power level of 44.5 dBm at 1 dB compression point.

Mutations in Burnt-Clay Brick Properties attributable to Waste Glass

Recently, the need of high living standards and developments in modern technology have significantly increased the usage of throwaway glass products. The use of these waste glass products in the production of construction materials (especially bricks) is ultimately very wholesome approach towards sustainable development. In this study, wasted glass up to 20% by weight was added to observe its impacts on bricks. The bricks containing powder glass were burnt along with ordinary bricks (with no powder glass) in same kiln and under same condition (type of fuel, temperature, duration etc.). The results illustrated that the properties of bricks vividly improved such as areal density, water absorption and efflorescence. The 20% increase of waste glass in the brick samples resulted in 14% decrease in areal density. The addition of fine powder glass filled the pores and reduced porosity of bricks. The substantial reduction in water absorption of 26.14% were observed with 20% addition of waste glass content. Also efflorescence was less in specimens having less quantity of waste glass burnt at higher temperatures. The present study presented a comprehensive analysis of waste glass as a mixing component for producing light weight sustainable bricks with improved water absorption properties.

Effect of Wind Load on Performance of Photovoltaic (PV) Modules Available in Pakistan

Mechanical integrity of a Photovoltaic (PV) module plays a major role in its performance and electrical output. Mechanical loads which include loads produced by wind, snow, rain, and hail tend to degrade the performance of PV module by generating stresses and enhancing micro-cracks and defects. This research aims to investigate the impact of wind loads on the performance of PV modules, particularly the degradation in its power output. A load of 2400 Pa was applied as per international standards (ASTM E1830-15 and IEC-61215). A total of four PV module samples, of the same specifications with 60 W rated power, were initially subjected to solar flash testing and Electroluminescence (EL) imaging. This was followed by three cycles of mechanical load test. After the mechanical load tests, the modules were again subjected to solar flash testing and EL imaging and the results were compared. It was noted that static wind load degrades the mechanical integrity of photovoltaic modules in two ways; by aiding the propagation of existing cracks and initiating new cracks. This loss of mechanical integrity degraded the power output of PV module. Maximum drop of 2% in the power output and 0.27% in the efficiency was observed. In addition, the average increase of 3.37% in the series resistance was observed indicating decrease in performance.

Model Based Indirect Conicity Estimation Technique for Solid Axle Railway Wheelset

Conicity is an important characteristic that helps the railway vehicle to steer itself down the track. However during the operation, the conicity tends to change inconsistently due to frictional contact at the wheel-rail interface. Safety, reliability and ride comfort which are utmost importance for journey are adversely affected due to the changes in conicity level beyond certain limit. Several techniques have been employed for monitoring the health of the railway wheelset however still a significant potential exists to investigate the wheelset conicity. This paper presents a model based technique to monitor the wheelset condition which contributes to the wheel flats due to decrease in conicity level and the problem of false flanges due to increased level of conicity. In this paper an unconstrained solid axle railway wheelset is considered for study. The dynamic behavior of the wheelset is analyzed at different conicity levels to understand the effect of the conicity on the wheelset. In order to demonstrate the potential of this research work a simulation model is developed in Matlab/ Simulink to mimic the behavior of an actual wheelset. Simplified linearized model of the wheelset is used to estimate the dynamics of the wheelset. From the simulation results it is evident that the frequency of vibration is changing with the changes in conicity level. In this way using the proposed method the conicity level is indirectly identified. The results produced by simulation model are satisfactory.