A cantilevered piezoelectric beam with a tip mass at its free end is a common energy harvester configuration. This paper introduces a new principle of designing such a harvester which increases the generated voltage without changing the natural frequency of the harvester: The attraction force between two permanent magnets is used to add stiffness to the system. This magnetic stiffening counters the effect of the tip mass on the natural frequency. Three setups incorporating piezoelectric bimorph cantilevers of the same type in different mechanical configurations are compared theoretically and experimentally to investigate the feasibility of this principle. Theoretical and experimental results show that magnetically stiffe

Heat is one of the most energy forms emitted to atmosphere by industrial processes. Water is considered to be the best material to reduce heat energy since its available in nature in abundance and has the ability to absorb heat efficiently. Cooling towers are ideal alternatives to re-cool hot water instead of throwing it especially in places that lack natural water resources or when there are environmental precautions because water with high temperature would be harmful to the ecosystem when it recycled to natural resources such as rivers and lakes. Also, cooling towers considered economically feasible when using west water. This paper interests with hydraulic characteristics of a counter flow wet cooling tower which was investigated experi

The aim of this research is to study the effect of high concentrations of salts, pressure and temperature on the performance of the RO membrane with time. Four different (Na2CO3) concentrations (5000, 15000, 25000 and 35000) ppm and various pressures such as (1, 3 and 5) bars at different temperatures of the feed solution (i.e., 25, 35 and 45) ◦C were used in this work. It was found that, as the concentration of salt and feed temperatures increase, the rejection of the salt decrease. While the salt rejection of the membranes increases with increase of transmembrane pressure.

        In this study the design and installation of evaporative air cooler was carried out using completely outdoor air (fresh air) according to two stage evaporative cooling principle. The laboratory equipment was installed by designing and manufacturing a cross flow plate heat exchanger, where aluminum plates used for this purpose with dimensions (50 × 30 × 40 cm). The surfaces of heat exchanger were covered by sawdust from wetted channels side, to increase the percentage of wetting these surfaces and hence improve the performance and efficiency of air cooler.

        An experimental study was carried out to estimate the performance of cooling system, where som

The rate of gas induction was measured in gas-inducing type mechanically agitated contactors provided with two impellers. A reactor of 0.5 m i.d. was used with a working capacity of 60 liters of liquid. Tap water was used as the liquid phase, and air was used as the gas phase. The bioreactor mixing system consists of two equal diameter stirrers; the top impeller is shrouded-disk/curved-blade turbine with six evacuated bending blades, while the bottom impeller was disk turbine. The impeller speed was varied in the range of 50 to 800 rpm. The ratio of impeller diameter to tank diameter (D/T) and the submergence (S) of upper impeller from the top were varied. The effects of clearance of lower impeller from the tank bottom (C₂) an

Abstract

The research aims to study the role of e-government in enhancing institutional performance. The dimensions of e-government are: (support and commitment of senior management, technical structures, organization and human resources, knowledge and information, work procedures, attention to citizens' satisfaction, and client parties),while the dimensions of institutional performance are: (Service improvement, innovation, efficiency and effectiveness).

The research used electronic questionnaire as a main tool for data collection, The questionnaire included all the employees in the e-government project in Department of Government Coordinate and Citizen Affairs at the General Secretariat of the C

This research aimed at studying the role of calculated knowledge an its efficiency in improving the performance especially most of the organizations are living within knowledge era which concentrate on new technology investment in different fields of modern live . Under the scientific trends towards the economy of calculated knowledge which depend basically on new computer program in order to utilize the knowledge to raise the level of work performance exploiting different resources in the best way that helps the organizations to achieve their objectives because the information technology and computer programs became a means of survival and indispensible instrument within the developed world which depend on prosperity . progress

The main purpose of this research is to diagnose the role of the Knowledge Accumulation of Human Resources KAHR in Strategic Performance SP, and for that, the research was applied to the represented sample by the administrative leaders consisting of (108) individuals distributed according to their positions and the organizational structure of the ministry. Correlations, effects, and benefits from generalizing the results in the field of research. The research involved a mixed-methods approach through two stages. During the first stage, the researcher gathered quantitative data from a questionnaire. The second stage gathered qualitative data to explore the survey results more deeply by conducting individual interviews with a sub-sample of

Photonic Crystal Fiber Interferometers (PCFIs) are greatly used
for sensing applications. This work presents the fabrication and
characterization of a relative humidity sensor based on Mach-
Zehnder Interferometer (MZI), which operates in reflection mode.
The humidity sensor operation based on the adsorption and
desorption of water vapour at the silica-air interface within the PCF.
The fabrication of this sensor is simple, it only includes splicing and
cleaving the PCF with SMF.PCF (LMA-10) with a certain length
spliced to SMF (Corning-28).
The spectrum of PCFI exhibits good sensitivity to humidity
variations. The PCFI response is observed for a range of humidity
values from (27% RH to 85% RH), the positi