Effects of fibre surface composition on mechanical properties of steel fibre reinforced mortars

Compressive strengths of mortars reinforced under similar conditions by mild steel, stainless steel and brass-coated steel fibres are shown to be independent of the type of fibre used. Flexural strengths are, however, significantly influenced by fibre surface composition and the effect is correlated with the magnitude of fibre/matrix adhesion. To exploit more effectively the improved adhesion obtainable with brass-coated steel fibres, the cohesive strength of the matrix requires improvement.     

Comparison between the steady-state performance of self-excitedreluctance and induction generators

A comparison of the steady-state performance of self-excited reluctance and induction generators is presented. Segmental and salient-rotors are built to suit the stator of a three-phase induction machine. The machine is operated in the two modes of generation. Results from computer models for no-load and load conditions are confirmed with experimental results. The results of the two generation modes are compared. It is shown that the reluctance generator has an equal chance of being used for wind-power generation. In addition, it has the advantage of operating at a fixed frequency. Although both types of rotors may be used, better performance is obtained from segmental-rotors     

Chronic obstructive pulmonary disease stage and health-related quality of life. The Quality of Life of Chronic Obstructive Pulmonary Disease Study Group

BACKGROUND: The American Thoracic Society recently recommended that chronic obstructive pulmonary disease be staged on the basis of the percentage of predicted FEV1. OBJECTIVE: To examine 1) the relation between the american Thoracic Society system for staging chronic obstructive pulmonary disease and health-related quality of life and 2) the effect of self-reported comorbid conditions on health-related quality of life. DESIGN: Cross-sectional study. SETTING: Outpatient clinics of respiratory departments of four hospitals and one primary health care center in spain. PATIENTS: 321 consecutive male patients with chronic obstructive pulmonary disease. MEASUREMENTS: Functional respiratory impairment, FEV1, respiratory symptoms, and health-related quality of life. Respiratory symptoms and health-related quality of life were measured by using the Spanish version of the St. George's Respiratory Questionnaire and the Nottingham Health Profile. RESULTS: Patient scores on the St. George's Respiratory Questionnaire were moderately to strongly associated with disease staging (r = 0.27 to 0.51). Compared with reference values, values for health-related quality of life for patients with stage I disease were substantially higher on the St. George's Respiratory Questionnaire (6 and 34; p < 0.001) and values for impairment were significantly greater in stage 1 patients with comorbid conditions (19 and 36; P = 0.001). At least one concomitant chronic condition was found in 84% of study patients. Comorbid conditions only partly influenced the observed pattern of deterioration of health-related quality of life with worsening stages of disease. CONCLUSION: Staging criteria for chronic obstructive pulmonary disease based on percentage of predicted FEV1 separated groups of patients with varying degrees of impairment in health-related quality of life. Contrary to expectations, even patients with mild disease showed substantially compromised health-related quality of life. Comorbid conditions influenced the relation between chronic obstructive pulmonary disease and health-related quality of life.     

Optimal Groundwater Management Using Genetic Algorithm in El-Farafra Oasis,Western Desert,Egypt

Groundwater is the unique source of fresh water in El-Farafra Oasis, western desert, Egypt. The increasing demand of groundwater in El-Farafra Oasis has resulted in an indiscriminate exploitation of this source causing environmental hazards such as decline of groundwater levels and well interference. In this paper, the study of these problems is conducted. The methodology introduced in this paper includes application of mathematical and Genetic Algorithm (GA) techniques. This situation has led to a growing realization that through good management, use of groundwater can be made more productive and sustainable. The proposed model of optimization is based on the combination of the MODFLOW with GA. The performance of the proposed model is tested on groundwater management problem (maximization of total pumping rate from an aquifer at steady-state). The results show that the GA solutions nearly agree with the solutions of other methods of previous works. Thus, it can be used to solve the management problems in groundwater. This model is used to develop the optimal pumping rate and number of wells in El-Farafra Oasis under different scenarios. The results show that under the current situation, the optimal pumping rate is 183023 m³/day. The second scenario assumes an increase of number of wells by 20%, the optimal rate reaches 220016 m³/day. The third scenario proposes pumping rate 254484 m³/day which equalizes an increase in the cultivated area by 4000 acres, the optimal rate reaches 258007 m³/day.     

钢节点板的渐进结构优化设计

渐进结构优化法被用于确定轴力作用下钢节点板的最优形状。采用一系列不同的节点板应用在不同类型的连接中,然后采用渐进结构优化法来寻找在这些连接中最佳形状的节点板。第一个例子假定节点板具有两个孔,可以用于带张力的双角钢连接,分析了某些参数如材料去除率、网格尺寸和带孔模型的最终形状。带3、4、5个孔的节点板同时也被设计为最佳形状。此外,设计模型包括两排多孔、错排多孔连接。最后,在单个螺栓连接中优化确定的形状与目前实际使用的非常相似,然而其重量更轻。那些为多重连接和焊接双角连接的形状目前还不可预测。这表明渐进结构优化法在确定节点板最佳形状方面还有研究的潜力。     

Impact of porosity and thickness of nano‐TiO2 films on the corrosion protection performance of C‐steel in H2SO4

The current study investigates the improvement in the corrosion protection performance of C‐steel after being dip‐coated with nano films from both pure TiO₂ and poly ethylene glycol (PEG) modified TiO₂. Characterization of the deposited TiO₂ films was performed by different techniques. Effect of morphology, porosity, and thickness of the deposited TiO₂ layers were also studied. Results revealed an increased corrosion protection of both coated TiO₂ films as compared to uncoated samples, with pure TiO₂ (without PEG) samples showing higher protection. Moreover, increasing the layer thickness of both types of TiO₂ coated films improved the protective properties.     

An efficient method for image forgery detection based on trigonometric transforms and deep learning

Multimedia Tools and Applications - Image forgery detection is the basic key to solve many problems, especially social problems such as those in Facebook, and court cases. The common form of image...     

Wide Bandgap Sb2S3 Solar Cells

The wide bandgap Sb₂S₃ is considered to be one of the most promising absorber layers in single-junction solar cells and a suitable top-cell candidate for multi-junction (tandem) solar cells. However, compared to mature thin-film technologies, Sb₂S₃ based thin-film solar cells are still lagging behind in the power conversion efficiency race, and the highest of just 7.5% has been achieved to date in a sensitized single-junction structure. Furthermore, to break single junction solar cell based Shockley–Queisser (S–Q) limits, tandem devices with wide bandgap top-cells and low bandgap bottom-cells hold a high potential for efficient light conversion. Though matured and desirable bottom-cell candidates like silicon (Si) are available, the corresponding mature wide bandgap top-cell candidates are still lacking. Hence, a literature review based on Sb₂S₃ solar cells is urgently warranted. In this review, the progress and present status of Sb₂S₃ solar cells are summarized. An emphasis is placed mainly on the improvement of absorber quality and device performance. Moreover, the low-performance causes and possible overcoming mechanisms are also explained. Last but not least, the potential and feasibility of Sb₂S₃ in tandem devices are vividly discussed. In the end, several strategies and perspectives for future research are outlined.     

Cache Memory Design for Single Bit Architecture with Different SenseAmplifiers

Most modern microprocessors have one or two levels of on-chip caches to make things run faster, but this is not always the case. Most of the time, these caches are made of static random access memory cells. They take up a lot of space on the chip and use a lot of electricity. A lot of the time, low power is more important than several aspects. This is true for phones and tablets. Cache memory design for single bit architecture consists of six transistors static random access memory cell, a circuit of write driver, and sense amplifiers (such as voltage differential sense amplifier, current differential sense amplifier, charge transfer differential sense amplifier, voltage latch sense amplifier, and current latch sense amplifier, all of which are compared on different resistance values in terms of a number of transistors, delay in sensing and consumption of power. The conclusion arises that single bit six transistor static random access memory cell voltage differential sense amplifier architecture consumes 11.34 μW of power which shows that power is reduced up to 83%, 77.75% reduction in the case of the current differential sense amplifier, 39.62% in case of charge transfer differential sense amplifier and 50% in case of voltage latch sense amplifier when compared to existing latch sense amplifier architecture. Furthermore, power reduction techniques are applied over different blocks of cache memory architecture to optimize energy. The single-bit six transistors static random access memory cell with forced tack technique and voltage differential sense amplifier with dual sleep technique consumes 8.078 μW of power, i.e., reduce 28% more power that makes single bit six transistor static random access memory cell with forced tack technique and voltage differential sense amplifier with dual sleep technique more energy efficient.     

Natural convection mass transfer at spheres

Mass transfer by natural convection at spheres has been studied by an electrochemical technique involving limiting current measurement for the anodic dissolution of copper spheres in phosphoric acid. Acid concentration and sphere diameter were changed to provide values ofSc. Gr ranging from 2.85×10¹⁰to 2.15×10¹¹; under these conditions the mass transfer data was correlated by the equation:Sh=0.15 (Sc. Gr)^0.33 Nomenclature I Limiting current density - K mass transfer coefficient - F Faraday's constant - C Saturation solubility of copper phosphate in phosphoric acid - Z number of electrons involved in the reaction - Sh Sherwood number=Kd/D - Sc Schmidt number=v _ave/D - Gr Grashof number=gd ³ ( _i– _b)/v _ave ² _i - d Sphere diameter - D diffusivity of copper ions - u _b viscosity in the bulk liquid - u _i viscosity at the interface - _b density in the bulk liquid - _i density at the interface - g acceleration due to gravity - v _ave average Kinematic viscosity - Nu Nusselt number - Pr Prandtl number