Energy of Cayley graphs for alternating groups

Let G be a finite group and S be a subset of G where S does not include the identity of G and is inverse closed. A Cayley graph of a finite group G with respect to the subset S is a graph where the vertices are the elements of G and two vertices a and b in G are adjacent if ab−1 are in the set S. For a simple graph, the energy of a graph can be determined by its eigenvalues. Let Γ be a simple graph. Then by the summation of the absolute values of the eigenvalues of the adjacency matrix of the graph, its energy can be determined. This paper presents the Cayley graphs of alternating groups with respect to the subset S of valency 1 and 2. From the Cayley graphs, the eigenvalues are computed by using some properties of special graphs and then used to compute their energy

WALL DESIGN FOR BORROWED DAYLIGHT IN ENCLOSED CORRIDORS

Previous studies by same authors, % DF values were calibrated comparing field work data to Radiance simulations and scaled model study for an enclosed corridor in tropical climate. Corridor walls are usually opaque resulting in very dark situations relying solely on artificial lighting. The objectives of this study in Paper 2 are to further investigate the extent of daylight which can be borrowed to light the internal enclosed corridors. This is carried out by experimenting on the various types of corridor wall designs with added transparent or glazed areas for daylight to be borrowed to the enclosed corridors. The designs experimented with various horizontal and vertical alternatives. The effects of these new corridor wall designs to daylight distribution in corridors are investigated by Radiance simulations. Results are compared to base case which is a situation of all opaque walls for the corridors as the worst situation. The findings show that the newer designs of corridor walls can provide daylight to corridors with significant improvements. Even though the %DF found were very low, outdoor illuminance in tropics are high therefore it is still sufficient for corridor lighting. Corridors with 50% glazed areas in a 4 strips horizontal design was found to perform the best for allowing borrowed daylight to occur

A METHOD TO CALIBRATE PERCENTAGE DAYLIGHT FACTOR AT ENCLOSED INTERNAL CORRIDOR USING SCALED MODEL AND SIMULATION

Enclosed corridors are long and they usually have no window provisions and require electric lighting to be switched on for 24 hours continuously to operate. Some corridor designs have openings for daylight at the ends, while others supplement daylight at the middle. The most part of these corridors are dark and consuming a lot of nonrenewable energy from artificial light. This paper explores how enclosed internal corridors do get the benefits of daylight depending on the corridor designs. It explores how percentage DF (Daylight Factor) less than 1%, especially in Malaysia where the skies are bright, can be beneficial and useful. The illumination required for corridors are minimal according to standards. Field work measurements were taken in selected enclosed corridor of a hostel building on typical overcast days and readings on %DF were then recorded. A scaled model of similar design was built to be experimented in the artificial sky to get a same set of readings; followed by simulation using Radiance. Results show that the readings calibrate well between field work compared to the scaled model in artificial sky and simulation with less than 10% differences. It was found that values of %DF of 0.5 and below calibrated well. Comparison were also carried out in terms of absolute illuminance and it was found that daylight illuminance less than 40 lux in corridors should not be underestimatedand were still useful even though lower than the usual standards for corridor illumination. This successful calibration will be used for further experimentation how enclosed corridors can be naturally lit by simulations

The Potential of Shading Devices for Temperature Reduction in High-Rise Residential Buildings in the Tropics

AbstractThe present study focuses on the effect of shading devices on the indoor temperature of high-rise residential buildings in the hot–humid climate of Malaysia. Several methods can be employed to improve indoor thermal environment, including using a reflective glazing system, using light colors for external surfaces, and using the appropriate thermal properties of external walls and roofs. However, before using any of these methods, it is important to have an optimum shading device to reduce the solar radiation absorption that leads to an overheated indoor environment and an increase in cooling energy loads. Therefore, the main objective of the current paper is to find the extent of a building's solar heat gain and, consequently, the indoor air temperature that is influenced by the external shading devices. A computerized simulation tool (IES<VE>) is used to carry out the investigation, taking Penang as the empirical background of the hot–humid climate. The results indicate that egg-crate shading has a significant impact on decreasing discomfort hours compared with other shading types

Development of an empirical dust storm attenuation prediction model for microwave links in arid area – a proposed framework

Wireless communication service providers are currently facing challenges due to the congested frequencies spectrum which has imposed the use of higher and higher frequencies. However, higher frequency bands are more sensitive to weather condition and the microwave signal attenuation due to atmospheric particles increases rapidly at higher frequency bands. Consequently dust storms and other phenomena cause signal attenuation which can limit the performance of wireless communication systems for the frequencies above 10GHz in arid area. The paper aim is to show that real dust storm is a complex phenomena which is difficult to be described by the theoretical physical or mathematical models. An empirical dust storm prediction model based on the long term statistical observations of dust storm properties and its corresponding microwave signal levels will be a step forward to provide microwave link designers with a precise tool to rely on. This paper has proposed a research framework to collect necessary data from Khartoum, Sudan and develop an empirical attenuation prediction model

Simulation of Event-Based Technique for Harmonic Failures

MAR

Performance of force circulation cross-matrix absorber solar heater integrated with latent heat energy storage material

The utilization of thermal energy storage in the thermal absorber applications has been increasingly important especially in the application where there is a mismatch between energy demand and energy supply. This technology implies that the heat is stored during charging or discharging process through melting and freezing of the thermal energy storage material so that it can be used in the future. This paper presents the outcome of the experimental investigation on the performance of cross-matrix absorber (CMA) utilizing paraffin as the thermal energy storage material. Experiments were carried out by exposing the CMA under different artificial solar radiation (300 W/m2, 500 W/m2, 700 W/m2 and 900 W/m2) for 30 minutes followed by 30 minutes of discharging process. Based on the observation, it was found that smaller mass flow rate value of 0.005 kg/s gave the highest temperature output regardless of the intensity of solar radiation as compared to the other after 30 minutes of charging process. In terms of heat gain by the thermal absorber, it was concluded that the highest mass flow rate of 0.01 kg/s passing through the absorber lead to the higher heat gain by the CMA, hence prolonged the cooling down / discharging period as shows by the result, where case with maximum mass flow rate (0.01 kg/s) consistently contributed to the higher heat gain by the absorber. This feature is very useful in the solar thermal collector related applications such as crop drying and domestic building heating. The heat gain by the absorber is also contributed by the intensity of the solar radiation

Influence of sulfate and chloride on the mechanical properties of fired clay masonry wall

This paper presents the influence of aggressive environment on the mechanical properties of masonry systems. The investigation involved the measurement of strength and modulus of elasticity of single leaf brick masonry wall which were built from fired clay bricks in conjunction with designation (iii) mortar with proportions of 1: 1: 6 (OPC: lime: sand). After being constructed, the specimens were cured under polythene sheet for 14 days in a controlled environment room with 80 ± 5% relative humidity and temperature of 25 ± 2ºC. The specimens were then exposed to the solution containing sodium sulfate and sodium chloride. The strength and modulus of elasticity of the brickworks were determined at the ages of 28, 56 and 180 days. The strength and modulus of elasticity of the brickworks, unbonded bricks, and mortar prisms were determined at the ages of 28, 56 and 180 days to quantify the contribution of bricks and mortar on the deformation of the masonry walls. As a result, fired clay brickwork is not durable and deteriorate in the environment containing sodium sulfate but durable in sodium chloride. The deterioration of the brickwork clearly influenced by the deterioration of mortar joint. The present of sodium chloride also retarding the attack of sodium sulphate

Dynamic mechanical properties of Polyurethane Shape Memory Polymer Composites (SMPC) with different volume fractions of chopped strand mat glass fiber

Polyurethane shape memory polymer (SMP) are comparatively low in modulus. Hence, there is a need for incorporation of chopped strand mat glass fibers as reinforcing materials for the development of SMP composites (SMPC). In this study, glass fibers in different volume fractions which are 0%, 5%, 10%, 15% and 30% were used. The aim is to obtain the optimum volume fractions of glass fibers in SMPC based on the dynamic mechanical properties. The dynamic mechanical analysis (DMA) was carried out to determine the dynamic mechanical properties of the composite material. The dynamic parameters which reliance to temperature such as storage modulus (E’), loss modulus (Eâ€), damping factor (tan δ), glass transition temperature (Tg) values and others will gives the data regarding the adhesion of fiber-matrix of the composite material. The result shows that upon the addition of reinforcing fibers, an improvement in storage modulus was obtained. The tan δ peak value were decrease when the fiber volume fractions were increased, which confirming the reinforcing effectiveness of glass fibers in SMPC. It was also observed that the (Tg) increase upon the addition of reinforcing glass fibers. Summarizing, 15SMPC was chosen as the optimum volume fractions of glass fibers in SMPC. The parameter of the damping vibration demonstrates main significance for civil applications for building reliability and performance enhancement. Besides, it can foresee the impacts of temperature and time towards the polymer viscoelastic performance under various conditions. This study will provide several information to determine its functional application in future research