Determination of aerosol extinction coefficient and mass extinction efficiency by DOAS with a flashlight source

With the method of differential optical absorption spectroscopy （DOAS）, average concentrations of aerosol particles along light path were measured with a flashlight source in Chiba area during the period of one month. The optical thickness at 550 nm is compared with the concentration of ground-measured suspended particulate matter （SPM）. Good correlations are found between the DOAS and SPM data, leading to the determination of the aerosol mass extinction efficiency （MEE） to be possible in the lower troposphere. The average MEE value is about 7.6m^2.g^-1 , and the parameter exhibits a good correlation with the particle size as determined from the wavelength dependence of the DOAS signal intensity.

Calculating the shading reduction coefficient of photovoltaic system efficiency using the anisotropic sky scattering model

The front-row shading reduction coefficient is a key parameter used to calculate the system efficiency of a photovoltaic(PV)power station.Based on the Hay anisotropic sky scattering model,the variation rule of solar radiation intensity on the surface of the PV array during the shaded period is simulated,combined with the voltage-current characteristics of the PV modules,and the shadow occlusion operating mode of the PV array is modeled.A method for calculating the loss coefficient of front shadow occlusion based on the division of the PV cell string unit and Hay anisotropic sky scattering model is proposed.This algorithm can accurately evaluate the degree of influence of the PV array layout,wiring mode,array spacing,PV module specifications,and solar radiation on PV power station system efficiency.It provides a basis for optimizing the PV array layout,reducing system loss,and improving PV system efficiency.

Investigating the Efficiency Coefficient of Pile Group in Clay Under Two-Way Lateral Load

This research investigates the behavior of a 2×2 pile group under two-directional lateral loads in addition to the vertical load.Through three-dimensional numerical modeling based on Flac 3D software,the study examines the total bearing capacity and efficiency coefficient of the pile group,considering factors such as the angle of lateral load,relative pile spacing,and relative stiffness of the pile-soil system.The findings highlight the significance of these factors in understanding and predicting the response of pile groups to changing lateral load directions.The results reveal that increasing the angle of the lateral load from 0°to 45°enhances both the maximum total lateral load and the efficiency coefficient of the pile group.When the relative stiffness of the pile-soil system significantly increases,soil stiffening occurs and reducing the relative spacing of the piles from 7 to 3 times the diameter of the piles diminishes the influence of the pile group.Consequently,the response of the pile group to lateral loads becomes more linear,with only a slight alteration in the maximum total lateral load and the efficiency coefficient when the lateral load is angled from 0°to 45°.Conversely,increasing the relative distance between the piles,specifically from 3 to 7 times the diameter of the piles,amplifies the influence of the pile group.Both the maximum total lateral load and the efficiency coefficient of the pile group exhibit an observed increase.These provide insights for designing pile groups and optimizing their performance under lateral loading conditions.

Direct Analytical Method to Calculate Photopeak Efficiency and Photopeak Attenuation Coefficient of NaI(Tl) Well-Type Detector

In this paper full-energy peak (photopeak) efficiency and photopeak attenuation coefficient of 3'' × 3'' NaI(Tl) well-type scintillation detector were calculated using gamma-rayisotropic radiating point sources (with photon energy: 0.245, 0.344, 0.662, 0.779, 0.964, 1.1732, 1.333 and 1.408 MeV) placed outside the detector well. These energies were obtained from 152Eu, 137Cs and 60Co. The relations between the full energy peak efficiency and photopeak attenuation coefficients, were plotted vs. photon energy at different sources to detector distance, and it found that the full energy peak efficiency decreased by increasing the distance between the source and the detector.

Evapotranspiration, Yield and Crop Coefficient of Irrigated Maize Under Straw Mulch

Maize (Zea mays L.), a staple crop grown from June to September during the rainy season on the North China Plain,is usually inter-planted in winter wheat (Triticum aestivum L.) fields about one week before harvesting of the winterwheat. In order to improve irrigation efficiency in this region of serious water shortage, field studies in 1999 and 2001, twodry seasons with less than average seasonal rainfall, were conducted with up to five irrigation applications to determineevapotranspiration, calculate the crop coefficient, and optimize the irrigation schedule with maize under mulch, as well asto establish the effects of irrigation timing and the number of applications on grain yield and water use efficiency (WUE)of maize. Results showed that with grain production at about 8 000 kg ha-1 the total evapotranspiration and WUE ofirrigated maize under mulch were about 380-400 mm and 2.0-2.2 kg m-3, respectively. Also in 2001 WUE of maizewith mulch for the treatment with three irrigations was 11.8% better than that without mulch. In the 1999 and 2001seasons, maize yield significantly improved (P = 0.05) with four irrigation applications, however, further increases werenot significant. At the same time there were no significant differences for WUE with two to four irrigation applications.In the 2001 season mulch lead to a decrease of 50 mm in the total soil evaporation, and the maize crop coefficient undermulch varied between 0.3-1.3 with a seasonal average of 1.0.

Influence of Density on Sound Absorption Coefficient of Fibre Board

For acoustic applications such as theaters, cinema halls, auditoriums the data on acoustic properties i.e. sound absorption coefficient and sound transmission loss are required to evaluate the acoustic behavior of panel products and to facilitate the necessary design computations. Fibre boards are widely used in private and commercial buildings, but not much data are available on acoustic efficiency of fibre boards. The study was carried using acoustic pulse tester based on standing wave method for evaluating sound absorption coefficient. Wood fibre boards of different densities ranging from 200 to 800 kg/m3 were taken and their sound absorption coefficients at frequencies ranging from 125 Hz to 4000 Hz were evaluated in third octave band. Noise reduction coefficient of the samples was also computed. From the study, it is observed that low density fibre board possess high sound absorption coefficient and noise reduction coefficient when compared with high density fibre boards. It was seen that sound absorption coefficient increases with decrease in density and vice versa.

Mass transfer coefficient in the eductor liquid-liquid extraction column

In this research gasoil desalting was investigated from mass transfer point of view in an eductor liquid–liquid extraction column(eductor-LLE device).Mass transfer characteristics of the eductor-LLE device were evaluated and an empirical correlation was obtained by dimensional analysis of the dispersed phase Sherwood number.The Results showed that the overall mass transfer coefficient of the dispersed phase and extraction efficiency have been increased by increasing Sauter mean diameter(SMD)and decreasing the nozzle diameter from 2 to 1 mm,respectively.The effects of Reynolds number(R_(e)),projection ratio(ratio of the distance between venturi throat and nozzle tip to venturi throat diameter,Rpr),venturi throat area to nozzle area ratio(R_(th-n))and two phases flow rates ratio(R_(Q))on the mass transfer coefficient(K)were determined.According to the results,K increase with increasing Re and RQ and also with decreasing Rpr and R_(th-n).Semi-empirical models of drop formation,rising and coalescence were compared with our proposed empirical model.It was revealed that the present model provided a relatively good fitting for the mass transfer model of drop coalescence.Moreover,experimental data were in better agreement with calculated data with AARE value of 0.085.

Calculation method of quantum efficiency to TiO_2 nanocrystal photocatalysis reaction

The quantum yield is an important factor to evaluate the efficiency of photoreactor. This article gives an overall calculation method of the quantum efficiency( Φ ) and the apparent quantum efficiency( Φ a) to the TiO 2/UV photocatalysis system. Furthermore, for the immobility system (IS), the formulation of the faction of light absorbed by the TiO 2 thin film is proposed so as to calculate the quantum efficiency by using the measured value and theoretic calculated value of transmissivity (T). For the suspension system(SS), due to the difficulty to obtain the absorption coefficient ( α ) of TiO 2 particulates, the quantum efficiency is calculated by means of the relative photonic efficiency ( ζ r) and the standard quantum yield ( Φ standard ).

The Onsager reciprocity relation and generalized efficiency of a thermal Brownian motor

Based on a general model of Brownian motors, the Onsager coefficients and generalized efficiency of a thermal Brownian motor are calculated analytically. It is found that the Onsager reciprocity relation holds and the Onsager coefficients are not affected by the kinetic energy change due to the particle＇s motion. Only when the heat leak in the system is negligible can the determinant of the Onsager matrix vanish. Moreover, the influence of the main parameters characterizing the model on the generalized efficiency of the Brownian motor is discussed in detail. The characteristic curves of the generalized efficiency varying with these parameters are presented, and the maximum generalized efficiency and the corresponding optimum parameters are determined. The results obtained here are of general significance. They are used to analyze the performance characteristics of the Brownian motors operating in the three interesting cases with zero heat leak, zero average drift velocity or a linear response relation, so that some important conclusions in current references are directly included in some limit cases of the present paper.

Efficiency of soil and water conservation practices in different agro-ecological environments in the Upper Blue Nile Basin of Ethiopia

In developing countries such as Ethiopia, research to develop and promote soil and water conservation practices rarely addressed regional diversity. Using a water-balance approach in this study, we used runoff plots from three sites, each representing a different agro-ecological environment, e.g., high, mid and low in both elevation and rainfall, in the Upper Blue Nile Basin of Ethiopia to examine the runoff response and runoff conservation efficiency of a range of different soil and water conservation measures and their impacts on soil moisture. The plots at each site represented common land use types（cultivated vs. non-agricultural land use types） and slopes（gentle and steep）. Seasonal runoff from control plots in the highlands ranged 214–560 versus 253–475 mm at midlands and 119–200 mm at lowlands. The three soil and water conservation techniques applied in cultivated land increased runoff conservation efficiency by 32% to 51%, depending on the site. At the moist subtropical site in a highland region, soil and water conservation increased soil moisture enough to potentially cause waterlogging, which was absent at the lowrainfall sites. Soil bunds combined with Vetiveria zizanioides grass in cultivated land and short trenches in grassland conserved the most runoff（51% and 55%, respectively）. Runoff responses showed high spatial variation within and between land use types, causing high variation in soil and water conservation efficiency. Our results highlight the need to understand the role of the agro-ecological environment in the success of soil and water conservation measures to control runoff and hydrological dynamics. This understanding will support policy development to promote the adoption of suitable techniques that can be tested at other locations with similar soil, climatic, and topographic conditions.

A New Type of Paper-frame Cavernous Material and Its Application in Energy Efficiency in Buildings

This paper introduces a new type of paper-frame cavernous material, which is a made-up hollow material, by using silicate-cinder size to drench and daub. It possesses excellent performances such as light-weight, high-intensity, fire-resistance, sound-insulation, heat-insulation and no-pollution. Composed with concrete materials, a new type of bearing and energy-efficient block can be gained, which is kind of excellent wall materials and has a wide application prospect.

Massive MIMO system lower bound spectral efficiency analysis with precoding and perfect CSI

The analytical lower bound of Spectral Efficiency(SE)of downlink transmission of the Massive Multiple Input Multiple Output(Ma-MIMO)system is analyzed.In this paper,we derive some novel and approximate mathematical expressions for the lower bound of the SE of a Ma-MIMO with linear precoding schemes,i.e.,Minimum Mean Square Error(MMSE)and Zero-Forcing(ZF).For simulation analysis of the SE,we consider three joint users and antenna scheduling algorithms,namely,the semi-orthogonal,random,and distance-based user scheduling algorithms,whereas the antennas are selected based on Maximum Signal to Noise Ratio(MSNR)with scheduled users.The channel between the user and the transmitter is assumed to have characteristics of Small Scale Fading(SSF)and Large Scale Fading(LSF)with the Rayleigh fading model.We investigate the effect of the variation of transmitting SNR,the number of base station antennas(M),and the radius(R)of the cell area on the SE.We simulate the downlink transmission of Ma-MIMO and compare the simulation and analytical results.It is observed that the trends of variation of both results are similar to the variation of identical factors,and the difference between the simulated and analytical lower bounds of the SE is approximately 1-1.5 bits.The analytical lower bound is smaller than the simulation result.

A novel receiver-transmitter metasurface for a high-aperture-efficiency Fabry-Perot resonator antenna

This paper presents a novel coupled receiver-transmitter metasurface(MS)which is used to realize a high-aperture-efficiency Fabry-Perot resonator antenna.The unit cell of the MS adopts a slot-coupling procedure to realize energy transmission from the receiver patch to the radiator patch.This approach makes it easier to independently control the transmission magnitude and phase.Based on this characteristic,the transmission coefficients of different unit cells on the MS can be optimized by a genetic algorithm.Then,nearly uniform electric amplitude and phase distribution across the aperture field of the antenna are achieved.Therefore,the gain and aperture efficiency of the antenna are improved.A prototype of the optimized antenna is fabricated and measured to validate the design.The measured gain of the fabricated antenna reaches 17.3 dBi with an aperture efficiency of 94.5%.A higher aperture efficiency is obtained with the proposed antenna which has a low profile and simple structure.

Audit Committee, Value Creation Efficiency and Capital Employed Efficiency

This study contributes a number of innovative and interesting empirical findings with a view of four audit committee characteristics to predict overall value creation efficiency and capital employed efficiency using value added intellectual coefficient （VAICTM） method. Using purposive sampling, 34 property, real estate, and building construction firms listed on Indonesia Stock Exchange in 2011 were selected. Empirical findings could not provide a significant relationship between audit committee characteristics and the overall value creation efficiency as well as capital employed efficiency. This implies that currently, the number of members, number of meetings, number of independent commissioners, and accounting or finance expertise in audit committee cannot be expected as drivers of business value creation in Indonesian context, more specifically for property, real estate, and building construction industry. The overall lack of significant relationships may potentially result from limited human capacity, lack of financial expertise, and inadequate knowledge about the role of audit committee to add value to the business.

Influence of Condensing Temperature on Heat Pump Efficiency

The thermodynamic aspect of a compression type heat pump （HP） is briefly described and special attention is given to investigation of condensing temperature influence on heat pump efficiency in heating mode, expressed by its coefficient of performance （COP）. Heat pumps are usually applied for the purposes of heating and cooling of energy efficient buildings where they have advantages in low-temperature systems, as it is well documented in the paper. The comparison of real thermodynamic processes with thermodynamically most favorable Camot＇s process is made. The results in the paper show that COP is diminishing with increasing of condensing temperature and also depends on real properties of working fluids. The impact of compressor efficiency for two real working media is also analyzed in the paper. There is significant diminishing of COP with diminishing of compressor efficiency. The intension of the paper is to help better understanding of this very effective and prosperous technology, and to encourage its development, production, and efficient application.

Enhanced flushing of polychlorinated biphenyls contaminated sands using surfactant foam: Effect of partition coefficient and sweep efficiency

Foam flushing is an in situ soil remediation technology based on the traditional surfactant flushing method. The contribution of mobility control to contaminant removal by foam is helpful for improving this technology. Foam flushing of polychlorinated biphenyl （PCB）- contaminated unconsolidated media was performed to evaluate the effect of the partition coefficient （PC） and sweep efficiency （SE） on PCB removal. Column flushing with surfactant solution and foam with different types and concentrations of surfactant was carried out for PCB removal. Two types of quartz sand were investigated to evaluate the Jamin effect on the SE value of the washing agent. The results demonstrate that a small PC value and large SE value are necessary to achieve high PCB removal for foam flushing. Compared with solution flushing, the introduction of foam can effectively control the mobility of the washing agent. Similar to solution flushing, solubilization is a key factor which dominates the removal of PCBs in foam flushing, In addition, the SE value and PCB removal by foam flushing is less affected by particle size. Therefore, foam flushing was proved to be more effective in porous media with low hydraulic conductivity and high porosity. An integrated flushing with water, surfactant solution and foam was performed and the results prove that this technology successfully combines the advantages of solution solubilization and mobility control by foam, and thus further increases the remediation efficiency of PCBs to 94.7% for coarse sand.

Quantum efficiency and temperature coefficients of GaInP/GaAs dual-junction solar cell

GaInP/GaAs dual-junction solar cell with a conversion efficiency of 25.2% has been fabricated using metalorganic chemical vapor deposition (MOCVD) technique. Quantum efficiencies of the solar cell were measured within a temperature range from 25 to 160°C. The results indicate that the quantum efficiencies of the subcells increase slightly with the increasing temperature. And red-shift phenomena of absorption limit for all subcells are observed by increasing the cell’s work temperature, which are consistent with the viewpoint of energy gap narrowing effect. The short-circuit current density temperature coefficients dJ sc/dT of GaInP subcell and GaAs subcell are determined to be 8.9 and 7.4 μA/cm2/°C from the quantum efficiency data, respectively. And the open-circuit cell voltage temperature coefficients dV oc/dT calculated based on a theoretical equation are ?2.4 mV/°C and ?2.1 mV/°C for GaInP subcell and GaAs subcell.

Energy Efficient MAC Protocol for Wireless Full-Duplex Networks

The wireless full-duplex(FD) nodes can transmit and receive at the same time using the same frequency-band. Currently, the latest FD media access control(MAC) protocols mainly focus on how to convert the physical layer gains of FD nodes to the throughput gain of wireless FD networks, but pay little attention to the energy consumptions of FD nodes. In this paper, we propose an energy efficient FD MAC protocol. According to the values of self-interference cancellation coefficients corresponding to the nodes of each FD pair and the signal propagation attenuation, the proposed protocol can adaptively select the communication mode of the FD pair between the full-duplex and half-duplex. Also, the minimum transmit power for FD nodes can be obtained to achieve high energy efficiency. We develop an analytical model to characterize the performance of our protocol. The numerical results show that the proposed MAC protocol can optimize the system throughput and reduce the transmission energy consumptions of nodes simultaneously as compared with those of the existing works.

A calculation method for friction coefficient and meshing efficiency of plastic line gear pair under dry friction conditions

A calculation method for the friction coefficient and meshing efficiency of plastic line gear(LG)pair under dry friction conditions was studied theoretically and experimentally,taking a polyoxymethylene parallel line gear pair(POM PLGP)as an example.Firstly,the geometric and mechanical models of PLGP were built by considering the effects of misalignment and loaded deformation under the actual operating condition.Then,the friction coefficient of POM specimens was obtained via the ball-on-disk experiment,of which the value varies between 0.35 and 0.45 under the experimental conditions.The calculation formula for the friction coefficient of POM LG pair was obtained by fitting the friction coefficient of the POM specimens,and the meshing efficiency of POM LG pair was calculated based on the calculation formula for friction coefficient and the meshing efficiency calculation approach.Finally,the meshing efficiency of POM PLGP specimens was measured using a homemade gear meshing efficiency test rig.The experimental results validated the feasibility of the proposed calculation method for the friction coefficient and meshing efficiency of the plastic LG pair.This study provides a method for the calculation of the friction coefficient and meshing efficiency of plastic gear pairs under dry friction conditions.It also provides the basis for the wear calculation of plastic LG pair under dry friction conditions.

LIMITING BEHAVIOR OF RECURSIVE M-ESTIMATORS IN MULTIVARIATE LINEAR REGRESSION MODELS AND THEIR ASYMPTOTIC EFFICIENCIES

Recursive algorithms are very useful for computing M-estimators of regression coefficients and scatter parameters. In this article, it is shown that for a nondecreasing ul （t）, under some mild conditions the recursive M-estimators of regression coefficients and scatter parameters are strongly consistent and the recursive M-estimator of the regression coefficients is also asymptotically normal distributed. Furthermore, optimal recursive M-estimators, asymptotic efficiencies of recursive M-estimators and asymptotic relative efficiencies between recursive M-estimators of regression coefficients are studied.