THE CONVOLUTION OF SERIES AND ITS APPLICATION ON BAR STRUCTURE

The cascade model is widely applied in water-currents flow calculations. The mathematical background of the cascade models is convolution. The convolution, especially in the case of continuous functions, is usually solved by Laplace transformation, which is handled with considerable difficulty. This study principally deals with convolution of series, rather than continuous functions. The convolution is traced back to the multiplication of the series´ characteristic polynomials. To find a suitable solution for this task, instead of the traditional definition of the linear space a more general definition was adopted. According to this adopted definition, the linear combination created by elements of module from vectors under addition in a way that the external relationship -instead of multiplying the vectors with real numbers- is solved by square matrixes. To cast the external relationship into a matrix multiplication form is possible because the algebraic structure found in the external relationship sufficient to be `ring´ according to the general definition of the linear space, and it is not required to be `field´ (body) as what used to be the common concept in traditional engineering practice. The method can be applied on any model that can be described by the linear differential equations with constant coefficients. To make it easy to follow each step of implementing the procedure it was demonstrated by application on one of the most simple bar structures, that is a Kelvin-Voigt type material model of cantilever

Recent Trends in Plasmonic Nanowire Solar Cells

Light trapping is crucial for low-cost and highly efficient nanowire (NW) solar cells (SCs). In order to increase the light absorption through the NWSCs, plasmonic materials can be incorporated inside or above the NW design. In this regard, two novel designs of plasmonic NWSCs are reported and analyzed using 3D finite difference time domain method. The geometrical parameters of the reported designs are studied to improve their electrical and optical efficiencies. The ultimate and power conversion efficiencies (PCE) are used to quantify the conversion efficiency of the light into electricity. The first design relies on funnel shaped SiNWs with plasmonic core while the cylindrical NWs of the second design are decorated by Ag diamond shaped. The calculated ultimate efficiency and PCE of the plasmonic funnel design are equal to 44% and 18.9%, respectively with an enhancement of 43.3 % over its cylindrical NWs counterpart. This enhancement can be explained by the coupling between the three optical modes, supported by the upper cylinder, lower cone and plasmonic material. Moreover, the cylindrical SiNWs decorated by Ag diamond offer an ultimate efficiency and short-circuit current density of 25.7%, and 21.03 mA∕cm2, respectively with an improvement of 63% over the conventional cylindrical SiNWs

Tapered Plasmonic Nanoantennas for Energy Harvesting Applications

In this chapter, novel designs of tapered-dipole nanoantennas are investigated for energy harvesting applications. A full systematic analysis for the proposed structure is presented where the harvesting efficiency, return loss, radiation pattern, and near-field enhancement are calculated using a finite-element frequency domain solver. Simulation results show that the proposed nanoantennas can achieve a harvesting efficiency of 60% at a wavelength of 500 nm where the antenna input impedance is matched to that of fabricated rectifying devices. Additionally, the cross-tapered nanoantenna offers a near-field enhancement factor of 252 V/m, which is relatively high compared to previously reported nanoantennas. The spatial and spectral resonance modes are investigated, and the simulation results indicate the ability of the cross geometry to be utilized in color-sorting applications. Moreover, the particle swarm optimization technique is adapted to configure the proposed designs for maximum performance

THE ROLE OF ACTIVITY BASED COSTING SYSTEM IN COST CONTROL IN SAUDI MANUFACTURING FIRMS

This study aimed at determining the role of activity-based costing system for cost control in Saudi manufacturing firms that produce "Raw Materials". The data was collected from 154 staff members with a job title of general managers, assistant managers, financial managers, and accountants working at Saudi manufacturing Firms that produce "Raw Materials" and listed in Saudi Stock Exchange and use ABC system at the end of July 2021 using a questionnaire that was developed and distributed to them. This study revealed that the ABC system; achieves production efficiency, increases the effectiveness of control over administrative and financial costs, and helps managers make cost and price decisions. The Researchers recommended that other Saudi manufacturing firms adopt the ABC system to reduce the cost of their products, greater production efficiency, and raise profitability

Floristic composition, life-forms and biological spectrum of Toor Al-Baha District, Lahej Governorate, Yemen

This paper enumerates 542 plant species belonging to 289 genera in 89 families of vascular plants collected from Toor Al-Baha district, Lahej governorate, Yemen, during 2008-2015. The Poaceae has the, relatively highest number of species (50 sp., 9.23%) followed by Asteraceae (38 sp., 7.01%), Euphorbiaceae (34 sp., 6.27%), Asclepiadaceae (30 sp., 5.54%), Fabaceae (28 sp., 5.17%) and Acanthaceae (26 sp., 4.80%). A genus represented by the greatest number of species is Euphorbia (19 species). Classification based on life form indicates that the chamaephytes (38.19%) comprise the largest proportion of the plants in the study area, followed by therophytes (28.60%) and phanerophytes (20.85%). The present results revealed that there are three parasitic species belong to two families these are: Cistanche phelypaea and Cistanche rosea (Orobanchaceae) and Striga angustifolia (Scrophulariaceae). Sixty three succulents taxa belong to eighteen families were recorded in the flora of the study area, among these families three are the richest ones (Asclepiadaceae 17, Euphorbiaceae 11 and Aloaceae 6)

Distribución y abundancia de los primeros estadios de desarrollo de Sardina pilchardus en el golfo de Túnez (Mediterráneo central) en relación con los factores ambientales

Four seasonal surveys were carried out in the Gulf of Tunis between summer 2002 and spring 2003 to study the abundance and distribution of Sardina pilchardus eggs and larvae in relation to environmental parameters. In the Gulf of Tunis, Sardina pilchardus begins spawning in autumn (23 eggs/10 m²) and attains its peak in winter (257 eggs/10 m²) when the mean SST is lowest (13.4°C). Sardine reproduction seems to be triggered by the decrease in the SST. In winter, the main spawning areas were located to the south of Zembra Island and the north of Cape Bon. Larvae were more abundant in winter (38 larvae/10 m²), while lower densities were collected in autumn and spring (1 larva/10 m²). The highest abundance of larvae (288 larvae/10 m²) was recorded southwest of Zembra Island. Eggs and larvae were mainly concentrated in the relatively warmer and saltier waters with high zooplankton abundance and, inversely, with a low concentration of nitrate and chlorophyll a and a low diatom abundance.Se llevaron a cabo cuatro campañas en el golfo de Túnez, entre verano del 2002 y primavera del 2003, con el objetivo de estudiar la abundancia y distribución de los huevos y larvas de Sardina pilchardus en relación con parámetros ambientales. En el golfo de Túnez Sardina pilchardus inicia la freza en otoño (23 huevos/10 m²), alcanzando el pico de puesta en invierno (257 huevos/10 m²), cuando la temperatura superficial media (SST) es mínima (13.4°C). La reproducción de la sardina se dispara al parecer por el descenso de la SST. En invierno, las principales áreas de puesta se localizaron al sur de la isla de Zembra y en el norte del Cabo Bon. Las larvas fueron más abundantes en invierno (38 larvas/10 m²); mientras que se recogieron menores densidades en otoño y primavera (1 larva/10 m²). La mayor abundancia larvaria (288 larvas/10 m²) fue observada en el suroeste de la isla de Zembra. Los huevos y larvas se concentraron principalmente en las aguas relativamente más cálidas y salinas, con altas abundancias de zooplancton, e inversamente bajas concentraciones de nitrato, clorofila a y abundancia de diatomeas

Áreas de puesta y distribución larvaria de anchoa Engraulis encrasicolus en relación con las condiciones ambientales en el Golfo de Túnez (Mediterráneo Central)

Early life stages of anchovy were investigated in the Gulf of Tunis by means of four seasonal surveys carried out from summer 2002 to spring 2003. Anchovy eggs and larvae were found all year round, but they were much more abundant in spring and summer. In spring, the main spawning area was located in the north of the Gulf, to the west and southwest of Zembra Island. In summer, higher egg and larva abundances were also observed to the southwest of Zembra Island, but secondary spawning grounds were detected in the vicinity of the mouths of the Rivers Majreda and Meliane. No direct correlations between sea surface temperature (SST), salinity (SSS) and chlorophyll a and the horizontal distribution of eggs and larvae were observed. However, egg distributions in all seasons and larval distributions in summer and autumn were significantly related to depth. The temporal variation of temperature seems to control the spawning intensity and the beginning of spawning seems to be triggered by the increase in SST.Se estudiaron los huevos y larvas de anchoa en el Golfo de Túnez por medio de cuatro campañas estacionales llevadas a cabo entre verano del 2002 y primavera del 2003. Los huevos y larvas de anchoa se encontraron a lo largo de todo el año; pero fueron mucho más abundantes en primavera y verano. En primavera, la principal área de puesta se localizó en el norte del Golfo, al oeste y suroeste de la isla de Zembra. En verano, las mayores concentraciones de huevos y larvas también se encontraron en el suroeste de la isla de Zembra; pero se detectaron áreas de puesta secundarias cerca de las desembocaduras de los ríos Majreda y Meliane. No se encontraron correlaciones directas entre la temperatura superficial (SST), la salinidad (SSS) y la clorofila a y la distribución horizontal de huevos y larvas de anchoa. Sin embargo, la distribución de huevos, durante todo el año, y las distribuciones larvarias, en verano y otoño, se relacionaron de forma significativa con la profundidad. La variación temporal de la temperatura parece controlar la intensidad de la puesta y el inicio de la freza parece dispararse por el incremento de la SST

RCS analysis on different targets and bistatic angles using LTE frequency

Moving target detection and location are a function of dependent bistatic Radar Cross Section (RCS) and radar design parameters which in our experimental study used long-term evolution (LTE) signal as a source for passive bistatic radar (PBR). Moving target also can be classified in positions of different bistatic radar angles using conventional processing approaches which we performed a simulation using Computer Simulation Technology (CST) Microwave studio. The target bistatic radar cross-section, sb will give a realistic calculation on PBR performance with the requirement of complete treatment. The targets used are Toyota Rush (SUV) and Proton Exora (compact MPV) as a moving target had been designed based on the actual size to observe the performance of RCS due to the changing of bistatic angle between transmitter and receiver. The frequency transmit signal from LTE based station is 2.6 GHz, far-field conditions and the material used for the moving target is perfect electrical conductor. Simulation used different bistatic angles which are 59° and 90° of plane wave propagation. The simulation results show that largest area of moving target had better outcome that reliable with Babinet's principle, which declares a target of physical cross-sectional area is proportionate to RCS. The variation of RCS also depends on the shape of moving target, size of moving target and angles of plane wave. This might improve the sensitivity elevation targets with an adjustment of receiver angle to the target and transmitter for a better RCS performance

Occupational hazard in urolithiasis patients in Qatar: a single-center cross-sectional study

Background: Urolithiasis is one of the most prevalent urological diseases and is associated with a substantial economic burden. Its prevalence varies according to geographical location. Qatar is a Middle Eastern country located in the Afro-Asian Stone Belt. It has a dry and hot climate, which may predispose individuals working in these environments to form kidney stones (KSs). Methods: A population sample of 4204 patients was categorized into five occupational classes. The frequencies and correlations of these occupations with KS formation were calculated. Results: Among the total cases, 2000 presented with KSs, with the majority being of Asian descent (49%), followed by individuals of Middle Eastern descent (35.1%). Technicians accounted for 35.15% of KS cases followed by clerks (29.2%) and executives (14.6%). Among KS cases, 44% had a single stone, 30% had multiple stones, and 26% had two stones. In comparing both KS and non-KS groups, age, gender, occupation, and race were significantly associated with KS formation (p-value 0.05). Asian males aged 31-40, working as technicians, were significantly more prone to urolithiasis. In comparing age, BMI, and gender with stone characteristics, only age was found significantly associated with stone size (p-value 500 HU in executives and clerks (p-value < 0.001). Conclusions: Our findings revealed an elevated risk of urolithiasis among certain occupational groups, particularly technicians, who frequently work outdoors in high-temperature environments. Alternatively, the sedentary nature of clerical and executive positions can also contribute to the risk of urolithiasis