In this research work, the performance of the measurement system (TDLAS) has been improved, it was connected to the computer for acquisition and processing data using the programming language MatLab. The internal surface of the cavity was coated by p
araffin wax, adsorption is significantly lowered.
This system has been employed to measure the concentration of ammonia in exhaled breath for 20 healthy volunteers in two cases (fasting and non-fasting), and 36 volunteers with chronic renal disease (before hemodialysis).
The walls containing phase change materials (PCM) play a significant role in the
air conditioning of buildings. However, one of the characteristics which limits the use
of PCMs is their low conductivity. It is possible to solve this problem by coup
ling a
metal matrix with the PCM. The aim of this study is to determine the optimal size of a
wall which allows a complete change of state, and a homogenization of the temperature
without a too fast change-of-state rate. To study the thermal behavior of the wall, we
have carried out a numerical simulation using the COMSOL® software in considering a
unit cell. To describe the change of state, the method of the equivalent heat capacity
has been used. Paraffin has been chosen as PCM (melting temperature 24.5 °C). The
influence of the nature and the volume fraction of the metal were determined. The case
of honeycombs made of aluminum has been specifically treated.
Our research includes the transmission mechanism of the wind turbine and the calculation of losses, such as loss of mechanical ventilation and friction loss and the loss of lubrication between the gear teeth design. Aims and access to high reliabili
ty work and thus obtain high efficiency and taking advantage of electronic programs, We observed that each type of previous losses have an impact on the overall loss of Gearbox, Depending on the working conditions, For example, at low speeds, loss of friction between the teeth is a great percentage of the total loss, And thus controls the overall efficiency of the transport system, while at high speeds noticed this low percentage of loss, while the loss of lubrication and ventilation rate rose.
The re-use of return air in central conditioning systems is one of the most important
procedures for saving power consumption. However, the requested fresh air of the people
existed within the conditioning space imposes determining the number of ti
mes to be used.
This research aims to link the work of the central conditioning system (heating) of a
facility with the number of people existing within this facility by modifying the ratio of
mixed fresh air and return air to save the electrical power consumption. Also, to raise the
temperature of the mixture air by controlling the flow of hot water continuously rather than
using on-off technique. As well as, to respond to any change in the number of people and
get rid of repeated machine starting.
Our research has been done by using specialized physical model consisted of test
room, heat and movement sensors, pump, water tank, heat exchanger and air mixing
blades. These devices are controlled by microcontroller type PIC16F877A.
The experimentally obtained results showed the ability of controlling the amount of
return air depending on the number of people and controlling the speed of the pump
continuously providing a saving of electrical energy consumption up to 68% compared
with the case of full speed.
نقدم نموذجاً جديداً من أجل حساب تردد الرنين للهوائي المطبوع الدائري الشكل بوجود
فجوة هواء بين القاعدة و الأرضي و بعدم وجودها.
على خلاف النماذج السابقة، هذا النموذج له تطبيقات واسعة على كل أقطار الهوائيات بدءاً
من الكبيرة و انتهاء بالصغيرة، مقارنة
مع سماكة الطبقة العازلة في أسفل الهوائي و أيضـاً
على كل القواعد التي تغطي مجال ثابت العازلية.
و قد قورنت القيم المحسوبة من أجل الأبعاد المختلفة للهوائي و لأنماط الـرنين مـع القـيم
المقاسة حيث لوحظ التوافق التام بينهما.
