机械密封上置式螺杆泵地面驱动装置研制

针对原机械密封下置式螺杆泵驱动装置维修更换需用吊车 ,现场操作不便的问题 ,研制了机械密封上置式驱动装置。该装置的特点之一是将机械密封移到装置上部 ,便于现场维修 ;特点之二是增设了光杆卡持器 ,不用吊车即可现场更换驱动装置。 10 0余口井的现场应用表明 ,这种机械密封上置式驱动装置最长无故障运转时间已超过 1a。

掌握新生的特点,加强教育的针对性——佛山师专86级新生调查

为了研究新生的特点,以便加强教育的针对性。86级新生进校后,对他们进行了一次征询意见活动。征询的内容有:新生报考师范志愿和对前途的看法;新生在校期间的奋斗目标和毕业后的目标;新生所关心的国家大事;新生所追求的自我形象等十个方面。 一、征询对象与方式 征询对象是86级的中文、英语、政史、数学、物理、化学和地理等七个专业的新生。征询对象共277人,其中来自城镇的有103人,其中男生占百分之四十。

Fabrication and Electromechanical Characteristics of 2×2 Torsion-Mirror Optical Switch Arrays with Monolithically Integrated Fiber Self-Holding Structures

Novel 2×2 torsion-mirror optical switch arrays are fabricated by using the mixed micromachining based on the surface and bulk silicon microelectronics,then are investigated electromechanically in applied direct and alternating electric fields.When the thickness of the elastic torsion beams suspending the aluminum coated polysilicon micro-mirrors of the switches in the arrays is about 1μm,the electrostatic yielding voltages for driving the mirrors to achieve their ON-state are in the range of 270～290V,and the minimum holding voltages for mirrors ON-state are found as 55V or so.Theoretical analysis manifests that the yielding voltage is more sensitive to beam thickness than other design parameters do about the torsion-mirror switch structures.The lifetime can reach 10 8 times.The estimated shortest switching time of the switches at least lasts for less than 2ms.The force analysis on the two kinds of new fiber self-holding structures integrated monolithically in the chip of the optical switch arrays indicates that the structures can feature self-fixing and self-aligning of optical fibers.

CATGUT IMPLANTATION AT ACUPOINT FOR PROTECTION FROM INJURY OF SPATIAL MEMORY IN THE RAT OF CONTINUATIVE ILLUMINATION

Objective To observe the injury of spatial memory in the rat of continuative illumination and the protection of catgut implantation at Nèiguān （内关 PC6） from the injury. Methods After training for 7 days in Morris＇s water maze of 4 quadrants, on the 8th day, 48 male Wistar rats of clear grade were randomly divided into a normal group, a model group, a melatonin （MT） group and a catgut implantation group, 12 rats each group. The spatial injury in the rats was induced by continuative and long-term （24 h and 42 days） illumination, and at the same time, they were treated with catgut implantation at Nèiguān （内关 PC6） and intraperitoneal injection of MT; changes of spatial memory ability and ultrastructures of the neurons of the hippocampus were detected by Morris＇s water maze and transmission electron microscope, respectively. Results The searching platform latency （SPL） in the Morris＇s water maze in the model group significantly prolonged as compared with that before modeling （P〈0.05）, and after treatment it was significantly shortened in the MT group and the catgut implantation group as compared with the model group （both P 〈 0.05）, but with no significant differences as compared with that before treatment （both P 〉0.05）. Mitochondria, synapses, axes and vascular endothelium in the hippocampus in the model group were injured in varying degrees, but a less injury was found in the MT group and the catgut implantation group which was similar to that in the normal group. Conclusion Catgut Implantation at Nèiguān （1内关 PC6） can protect from the injury of spatial memory in the rat of continuative illumination.

Design and fabrication of Panda-type erbium-doped polarization-maintaining fibres

To obtain the stable operation of erbium-doped fibre laser, the simple and ideal technology is adopted by use of the erbium doped polarization maintaining fibre （EDPMF）. The design criteria of the Panda-type EDPMF are presented, which take into account the cutoff wavelength, mode field diameter, modal birefringence and background loss. Four groups of optimum structural paramcter combinations are determined in terms of the design criteria. Two kinds of the Panda-type EDPMFs are selected to be fabricated. The fabrication process and the parameter control of the Panda-type EDPMFs are presented in detail. Their refractive index profiles, birefringence and absorption spectra are experimentally investigated. The absorption coefficient of the EDPMF, whose core is co-doped with Bi, Ga, A1 and Ge, is about 57.9dB/m at 1.53μm. Co-doping Bi, Ga and A1 can greatly increase the erbium concentration in the silica-based fibre. The high birefringence is obtained for the Panda-type EDPMF. The group birefringence of the EDPMF, whose outer cladding diameter is 125 μm, is about 4.8 × 10%^-4.

Photoelectrochemical nitrogen reduction:A step toward achieving sustainable ammonia synthesis

Industrial NH3 production mainly employs the well‐known Haber‐Bosch(H‐B)process,which is associated with significant energy consumption and carbon emissions.Photoelectrochemical nitro‐gen reduction reaction(PEC‐NRR)under ambient conditions is considered a promising alternative to the H‐B process and has been attracting increasing attention owing to its associated energy effi‐ciency and environmentally friendly characteristics.The performance of a PEC‐NRR system,such as the NH_(3) yield,selectivity,and stability,is essentially determined by its key component,the photo‐cathode.In this review,the latest progress in the development of photocathode materials employed in PEC‐NRR is evaluated.The fundamental mechanisms and essential features required for the PEC‐NRR are introduced,followed by a discussion of various types of photocathode materials,such as oxides,sulfides,selenides,black silicon,and black phosphorus.In particular,the PEC‐NRR reac‐tion mechanisms associated with these photocathode materials are reviewed in detail.Finally,the present challenges and future opportunities related to the further development of PEC‐NRR are also discussed.This review aims to improve the understanding of PEC‐NRR photocathode materials while also shedding light on the new concepts and significant innovations in this field.

Snow Cover Variation and Streamflow Simulation in a Snow-fed River Basin of the Northwest Himalaya

Snowmelt is an important component of any snow-fed river system.The Jhelum River is one such transnational mountain river flowing through India and Pakistan.The basin is minimally glacierized and its discharge is largely governed by seasonal snow cover and snowmelt.Therefore,accurate estimation of seasonal snow cover dynamics and snowmeltinduced runoff is important for sustainable water resource management in the region.The present study looks into spatio-temporal variations of snow cover for past decade and stream flow simulation in the Jhelum River basin.Snow cover extent(SCE) was estimated using MODIS(Moderate Resolution Imaging Spectrometer) sensor imageries.Normalized Difference Snow Index(NDSI) algorithm was used to generate multi-temporal time series snow cover maps.The results indicate large variation in snow cover distribution pattern and decreasing trend in different sub-basins of the Jhelum River.The relationship between SCE-temperature,SCE-discharge and discharge-precipitation was analyzed for different seasons and shows strong correlation.For streamflow simulation of the entire Jhelum basin Snow melt Runoff Model(SRM) used.A good correlation was observed between simulated stream flow and in-situ discharge.The monthly discharge contribution from different sub-basins to the total discharge of the Jhelum River was estimated using a modified version of runoff model based on temperature-index approach developed for small watersheds.Stream power - an indicator of the erosive capability of streams was also calculated for different sub-basins.

Optical-field-induced memory effect of nematic liquid crystal doped with zinc porphyrin dimers

In this paper, the optical-field-induced reorientation ofnematic liquid crystal （5CB） doped with a volume fraction of 1.0% of zinc porphyrin dimers ο, ο-C2-（L-Thr）-C2-（TPP）2Zn（II）2 has been studied. Excited by 1.06 lain, YAG laser pulse with 10 ns pulse duration and 100 mJ pulse energy, both of the doped 5CB and pure 5CB perform the reorientation. When the exciting laser pulse withdraws, the doped 5CB retains the reorientation and without back to the initial orientation, and the memory effect is formed accordingly, whereas the pure 5CB relax to the initial orientation. A model considering the intermolecular coupling change between the dopant and host 5CB, and together with the aligning surface adsorption process of deformed dopant are present to explain this memory effect. In order to prove this mechanism, 5CB doped with another dopant （zinc porphyrin, ZnTPP） was used for contrast, which induces no such memory effect. This phenomenon is very useful to study the optical data storage and memory display.

Automatic detection and removal of static shadows

In case of complex textures,existing static shadow detection and removal algorithms are prone to false detection of the pixels.To solve this problem,a static shadow detection and removal algorithm based on support vector machine(SVM)and region sub-block matching is proposed.Firstly,the original image is segmented into several superpixels,and these superpixels are clustered using mean-shift clustering algorithm in the superpixel sets.Secondly,these features such as color,texture,brightness,intensity and similarity of each area are extracted.These features are used as input of SVM to obtain shadow binary images through training in non-operational state.Thirdly,soft matting is used to smooth the boundary of shadow binary graph.Finally,after finding the best matching sub-block for shadow sub-block in the illumination region based on regional covariance feature and spatial distance,the shadow weighted average factor is introduced to partially correct the sub-block,and the light recovery operator is used to partially light the sub-block.The experimental results show the number of false detection of the pixels is reduced.In addition,it can remove shadows effectively for the image with rich textures and uneven shadows and make a natural transition at the boundary between shadow and light.

Diffusion of Solar Energy Use in the Built Environment Supported by New Design

Places of large potentials of sustainable energy production and places of large energy consumption are often very different and separated by large distances across the globe. This paper first discusses potentials of solar technology in terms of global availability using PV （photovoltaic） technology and actual energy production. Solar energy is widely under-used and one way to reduce this is to improve production in low-energy places with high demand： large cities. According to this option, about 40% of the electricity consumption in the built environment could be produced by solar PV systems and energy storage systems. This paper discusses conditions in the built environment and functional and design qualities enabling an increased diffusion of the technologies In a comparative analysis of PV technologies, the criteria taken into account encompass efficiency of the type of solar cell and commercial availability. Special attention is paid to the design features of different PV systems, like flexibility, colour and transparency that might help in their utilization as integrated in building material and ornaments in modem architecture. The same procedure is followed for electricity storage devices. The preliminary conclusion is that at present the freedom of design is largest for a combination of crystalline silicon PV cells and Li-ion batteries.

RESEARCH ON COLOR CONSTANCY UNDER OPEN ILLUMINATION CONDITIONS

Color information plays a key role in the research fields of object recognition and image retrieval. However, the actual color varies by the conditions of illumination, especially the open natural daylight. Four different color constancy schemes are proposed in the paper to minimize the effects of open illumination conditions. (1) The color constancy scheme based on the image statistics is proposed, which includes the color cast detection and removal. (2) The color constancy scheme based on the color temperature curve is proposed, which combines Gaussian model with linear fitting to estimate color temperature curve. (3) The color constancy scheme based on the double exposure theory is proposed, which is able to reproduce a color image under typical illumination. (4) According to the concepts of supervised learning, the supervised color constancy scheme is proposed. The transformation of color values from unknown illumination to typical illumination is solved by improved Support Vector Regression (SVR).

Daylighting Strategies： Building＇s Sustainability and Energy Efficiency

Improving daylighting strategy is a mandatory step to achieve visual enjoyment and energy saving in buildings. Psycho, physiological effects and energy performance have to be investigated in order to define a range of different daylighting strategies, thanks to daylighting devices and climate based daylight modeling. Daylighting optimization ensures indoor healthier rooms, reduces electric light consumption and cuts the risk of glare. The best way to achieve these targets is to define users lighting needs, based on visual targets and to draw up some green measures to reduce electricity demands. Involving new climate-based daylight modeling metrics aims at defining proper illumination targets, in order to drastically reduce electrical lights, as well as reducing thermal loads deriving from cooling and HVAC （heating, ventilation and air conditioning） systems.

Wavelet De-noising of Speech Using Singular Spectrum Analysis for Decomposition Level Selection

The problem of speech enhancement using threshold de-noising in wavelet domain was considered.The appropriate decomposition level is another key factor pertinent to de-noising performance.This paper proposed a new wavelet-based de-noising scheme that can improve the enhancement performance significantly in the presence of additive white Gaussian noise.The proposed algorithm can adaptively select the optimal decomposition level of wavelet transformation according to the characteristics of noisy speech.The experimental results demonstrate that this proposed algorithm outperforms the classical wavelet-based de-noising method and effectively improves the practicability of this kind of techniques.

Using Support Vector Regression to Analyze Urban Atmosphere Pollution with Optical Remote Sensing Data

The concentration of absorbable particulate matter less than 10 μm termed as PM10 is the most important urban air pollution index for air quality monitoring. This paper presents a space based PM10 monitoring algorithm based on QUAC （QUick atmosphere correction） for optical remote sensing data and SVR （support vector regression）. PM 10 concentration measurements from nine ground based stations in Hangzhou, China and the MODIS （moderate-resolution imaging spectroradiometer） images were analyzed. Experimental result indicates that the correlation between CD （correction differences） with actual measured data is better than correlation between AOD （aerosol optical depth） with measured data. In addition, the fitting performance of the SVR model established with CD and measured data is better than traditional regression models.

Persistence and Impact of a PGPR on Microbial Communities of Biosolids and Soil Amended with Them

Survival of the plant-growth promoting rhizobacteria （PGPR） strain Pseudomonasfluorescens 92 in two batches ofbiosolids and soil amended with them and functional and structural shifts occurring in the resident bacterial communities were assessed. Viability of the rifampicin resistant gfp-tagged P. fluorescens 92RTcgfp, inoculated in microcosms consisting of biosolids, soil amended with biosolids and soil, drastically decreased 3-7 days after inoculation in treatments containing biosolids and soil amended with them. The PGPR counts in biosolids were always lower than in soil throughout the experiment whereas, in soil amended with biosolids, were similar or higher depending on the batch of biosolid. Analysis of the community-level physiological profiling （CLPP） revealed a strong impact of the strain on the metabolic activities, as seen in a general uniformity of the inoculated microcosms profiles. According to single-strand conformation polymorphism （SSCP） analysis, the presence of the PGPR had no effect on the resident soil and biosolid eubacterial population, whereas it induced a transient shift in the composition of the resident pseudomonads. In conclusion, biosolids themselves are not suitable as inoculum vehicle for the PGPR nevertheless, their combined incorporation into soil increases the inoculum survival and buffers the competition effects with the resident communities.

Classification of hyperspectral remote sensing images based on simulated annealing genetic algorithm and multiple instance learning

A hybrid feature selection and classification strategy was proposed based on the simulated annealing genetic algonthrn and multiple instance learning （MIL）. The band selection method was proposed from subspace decomposition, which combines the simulated annealing algorithm with the genetic algorithm in choosing different cross-over and mutation probabilities, as well as mutation individuals. Then MIL was combined with image segmentation, clustering and support vector machine algorithms to classify hyperspectral image. The experimental results show that this proposed method can get high classification accuracy of 93.13% at small training samples and the weaknesses of the conventional methods are overcome.

Features of Excitation of a Two-Level System by Short Nonresonance Laser Pulses

This paper is devoted to theoretical investigation of characteristic features arising during excitation by short nonresonance laser pulses. The treatment is made within the applicability of perturbation is given to the dependence of total excitation probability from eigenfrequency of TLS. Various laser pulse shapes of TLS on the pulse duration for different detuning are considered. two-level system （TLS） approach. Main attention of carrier laser frequency

Overview of Abandoned Mines in the Limpopo Province, South Africa： Rehabilitation Challenges

South Africa is facing enormous financial, environmental and social challenges posed by abandoned mines. This investigation focused on field verification of 850 abandoned mines and associated rehabilitation challenges in the Limpopo Province. The investigations included desktop studies, standardised field-based ranking system and sampling. The waste material samples were analysed using XRF （X-ray fluorescence spectrometry） at the Council for Geoscience Laboratory. Approximately 5% of 850 abandoned mines in the Limpopo Province require urgent rehabilitation either due to high concentrations of metals from mine dumps or presence of open shafts. For example, copper concentrations at Messina and Spoedwel were 9,719 ppm and 56,160 ppm, respectively. Birthday Gold Mine in Giyani area is characterised by un-safe open shafts and un-stable grounds which poses safety problems and limits the future land-use. Although these investigations have been conducted, it is not possible to rehabilitate all abandoned mines mainly due to limited financial resources. The abandoned mines close to human settlement are given priority due to their immediate threat to people. This study recommends that rehabilitation of abandoned mines should take cognisance of the sustainable future land use that will favour the creation of jobs and nature conservation.

新的半导体器件

最近美国宣称有一种新的半导体器件,人们用它可以留影和记事,高兴用多少次都可以。这种器件主要是由许多单元所构成的嵌镶板,而每个单元又系由光激导电和电激发光两部分所组成。当这器件装光激导电部分就后,若在暗处对任一单元加上电压(图1),还不会发生什么效应。

The Temporal-Spatial Distribution of Light Intensity in Maize and Soybean Intercropping Systems

Intercropping can improve field microclimates, decrease the incidence of crop diseases, and increase crop yields, but the reasons for this remain unknown. Solar radiation is the most important environmental influence. To understand the mechanisms of intercropping we established an experiment consisting of three cropping patterns： a monocropping control {treatment A） and two intercropping treatments （B： two rows of maize and two rows of soybean intercropping; C： two rows of maize and four rows of soybean intercropping）. Results show that compared to monocropping, intercropping increased the amount of light penetrating to inferior leaves in maize plants. Light intensity reaching maize plants at the heading stage in intercropping increased over two-fold at 30 cm above ground and 10-fold at 70 cm above ground, compared with monocropping. At the flowering to maturity stage, light intensity at 110, 160 and 210 cm above ground among maize plants was greatly increased in intercropping compared with monocropping, by some five-fold, two-fold and 12%, respectively. Moreover, light intensity declined more slowly at the measured heights in the intercropping system compared with monocropping. From the 7-18th leaf, light intensity per leaf increased two-fold in intercropping compared with monocropping. Daily light duration increased more than a mean of 5 h per day per leaf in intercropping compared with monocropping. The biological characters of maize including thousand kernel weight, yield per plant and area of ear leaves were all greater in intercropping than monocropping. These results suggest that, for maize, intercropping improves light density and duration significantly and this may contribute to biomass and yield increases.