社会舆论的结构及社会声呐

对经济、政治和民情问题作出反应的不同类型的舆论,穿插融合、变动不居,形成复杂的结构和社会声呐系统。经济舆论是经济制度和经济运行的测度器,政治舆论昭示权力及其意识形态是否符合民意,民事舆论则显现政府的治理能力、社会伦理秩序和法治状况。三种舆论的交互演变勾勒出社会变动的轨迹,揭示社会发展的真切路径。在舆论声呐中,政府和民众通过意见交流寻找社会管理的最大共识,不断调整社会政策,使各种社会矛盾得到顺利解决。

勃鲁莱氏测高器刻度改进及用法

在林业教学、生产、科研上,立木测高经常碰到。测高器和测高仪的种类较多。勃鲁菜氏测高器,方法简单,携带方便,测高速度快而精确,为目前国内通用。使用勃鲁莱氏测高器时,先必须实测等于整数15、20、30、40米的水平距,整数水平距离在地势平坦地段容易测得,而在坡地上不容易测得或较繁琐。

A Novel Built-in CMOS Temperature Sensor for VLSI Circuits

A novel temperature sensor is developed and presented especially for the purpose of on-line thermal monitoring of VLSI chips.This sensor requires very small silicon area and low power consumption,and the simulation results show that its accuracy is in the order of 0.8℃.The proposed sensor can be easily implemented using regular CMOS process technologies,and can be easily integrated to any VLSI circuits to increase their reliability.

OBSERVER/FILTER STRUCTURE BASED ADAPTIVE FRICTION COMPENSATION FOR HIGH PRECISION TURNTABLE

Two adaptive friction compensation schemes are developed for a high precision turntable system with nonlinear dynamic friction to handle two types of parametric uncertainties in the friction. Both schemes utilize a nonlinear observer/filter structure to compensate for uncertainties in corresponding friction parameters associated with the turntable system. Moreover, in the second scheme, adjustable gains are introduced into the dual nonlin- ear filters and they can be tuned to improve the position tracking performance. In both cases, a Lyapunov-like argument is provided for the global asymptotic stability of the closed-loop system. Simulation results demonstrate the effectiveness of the proposed schemes.

An Analysis on the Mechanism Governing the Effect of Bomb Length upon the Sensitivity of Detection of a Capacitance Fuze

For a detector in a capacitanee fuze working in an electrostatic field, the bomblength (effective length of the conductor part) is an important factor affecting the sensitivityof detection. For the two different kinds of detecting circuit models in general use (the frequency-sensitive and the amplitude-coupling ), mechanism of the effect of bomblength on the sensitvity of detection is analyzed. Through the analysis a conclusion in fullagreement with experimental results has been drawn, that is. the longer the bomb length,the higher the sensitivity, on the condition that the sizes and the sites of the detecting electrodes and bomb diameter remain unchanged.

Sea water temperature auto-monitoring system based on general packet radio service (GPRS)

This paper introduces the design and implementation of sea-water temperature auto-monitoring system based on General Packet Radio Service （GPRS）. This system integrates modern wireless communication technology, the signal gathering technology and computer network technology. MSC1210 microcontroller is used in data collection device in order to make system accurate and fast. In addition, wireless and Internet technologies are used for transferring and displaying collected field data. A prototype system has been completed and tested in field trials. The results proved the feasibility and usefulness of this system for monitoring the temperature. By using this system, a lot of resources and money can be saved.

Design of dual Beam multi-wavelength UV-visible absorbance detectors based on CCD

Because the general multi-wavelength UV-Visible absorbance detector cannot avoid the noise and drift resulting from the intensity fluctuation of the light source,a dual beam multi-wavelength UV-Visible detector based on CCD was designed. The ray of light source is divided into a signal ray and a reference ray by the beam splitter after it passes through the chopper. The signal ray shines into the sample cell. The signal ray passing through the sample cell falls onto a concave mirror which focuses it onto a slot that is imaged on one portion of COD by a concave grating. The reference ray is imaged on the other portion of COD by the concave grating after the slot. The signal spectrum, the reference spectrum and the dark current of COD can be measured on the same CCD under the cooperation of the optical system and accessorial circuits. The real-time compensation for the signal spectrum by using the reference spectrum and the dark current of OCD can effectively depress the noise and drift of the detector. The short-term noise is 10^-5 AU and the drift is 10^-1 AU/h.

A review on quantitative analysis of suspended sediment concentrations

Information on the concentration of suspended sediments in coastal waters is necessary for the understanding and management of the coastal environment. Traditionally, suspended sediment concentration （SSC） has been measured by time-consuming and costly boat surveys which allow the accurate measurement of SSC for single points in space and time. In order to obtain the instantaneous measurement of SSC, a variety of remote sensing method has been adopted. Remote sensing from airborne and spaceborne sensors has been proven to be a useful adjunct to such surveys as it provides an instantaneous and synoptic view of sediments that would otherwise be unavailable. Dominique Durand and Jerome Bijaoui in 2000 presented a feasible study on optical remote sensing of shallow-water environmental parameters. Yogesh C. Agrawal and H. C. Pottsmith in 2001 tried to use Laser Diffraction Sensors to measure Concentration and Size Distribution of Suspended Sediment. Francisco Pedocchi and Marcelo H. Garcia in 2006 made an evaluation of the LISST-ST instrument for suspended particle size distribution and settling velocity measurements. H.K.Ha and W-Y.Hsu in 2009 tried to measure suspended cohesive sediment concentration using ADV backscatter strength. Shuisen Chen, Ligang Fang in 2009 managed to use remote sensing of turbidity in seawater intrusion reaches of Pearl River Estuary. In this article, the brief review of most of the technologies or methods used to observe the suspended sediment concentration is executed. As the most powerful technology in the remote sensing, acoustic backscatter device is discussed in detail. A comparison between those traditional and modern technologies is made to clarify its future application and development.

Coordinate unification method of high-precision composite measurement in two dimensions

Multi-sensor coordinate unification in dimensional metrology is used in order to get holistic, more accurate and reliable information about a workpiece based on several or multiple measurement values from one or more sensors. Because of the problem that standard ball is deficient as a standard artifact in the coordinate unification of high-precision composite measurement in two dimensions （2D） , a new method is proposed in this paper which uses angle gauge blocks as standard artifacts to achieve coordinate unification between the image sensor and the tactile probe. By comparing the standard ball with the angle gauge block as a standard artifact, theoretical analysis and experimental results are given to prove that it is more precise and more convenient to use angle gauge blocks as standard artifacts to achieve coordinate unification of high-precision composite measurement in two dimensions.

Study on Coaxiality Measurement System of Compound Gear Shaft Based on Non⁃contact Optic

Aiming at the shortcomings of traditional contact measurement methods such as low measurement efficiency,high cost and low accuracy,a non-contact optical measurement method based on the laser displacement sensor is proposed.According to the relevant regulations of the coaxiality error evaluation standard and the structural characteristics of the compound gear shaft,we have designed and built a set of supporting software system as well as a hardware test platform.In this paper,the distance difference threshold and scale threshold methods are used to eliminate outlier data.The least squares circle is selected to calculate the center of the circle and the minimum containment cylinder axis method is used as the reference axis of the composite gear shaft.Compensated by the standard step shaft calibration,the coaxiality error of the composite gear shaft can be measured to be within 0.01 mm in less than two minutes.The range value of the multi-section measurement test is 0.065 mm.The average coaxiality error is∅0.476 mm.

Design of a Weak Signal Detecting Circuit in the Infrared Spectrum Absorbed Type Gas Sensor

In the infrared spectrum absorbed type gas concentration sensor,voltage signal obtained from the two-channel thermopile infrared detector TPS2534 is very weak.In order to solve this problem,the authors have established the structure of the sensor and designed weak signal detecting circuit of the sensor based on infrared spectrum absorption principle,differential de-noising principle and weak signal detecting principle.The authors have made experiments using CH4 gas.The results show that the circuit can remove noise effectively and detect weak electrical signal obtained from the detector.

Measurement of oil volume fraction and velocity distributions in vertical oil-in-water flows using ERT and a local probe

This paper presents the use of a high performance dual-plane electrical resistance tomography (ERT) system and a local dual-sensor conductance probe to measure the vertical upward oil-in-water pipe flows in which the mean oil volume fraction is up to 23.1%. A sensitivity coefficient back-projection (SBP) algorithm was adopted to reconstruct the flow distributions and a cross correlation method was applied to obtain the oil velocity distributions. The oil volume fraction and velocity distributions obtained from both measurement techniques were compared and good agreement was found, which indicates that the ERT tech- nique can be used to measure the low fraction oil-water flows. Finally, the factors affecting measurement precision were discussed.

Application of Electrical Capacitance Tomography to the Concentration Measurement in a Cyclone Dipleg

Accurate solid concentration measurement plays a key role in the process industry. Measurements analyzed offline can be used to estimate process efficiencies, to identify problems in a flow, and to validate computational models. Online measurements can be used for active control. Electrical capacitance tomography （ECT） is a unique measuring technique with great potential in multiphase flow measurement. Experimental studies are carried out on a solid concentration measurement in a cyclone separator dipleg, using ECT. In this experiment eight electrodes are selected for the ECT sensor that is placed on the straight tube of the dipleg. The fluctuating characteristics according to the screw feeder and the effect of the airflow rate from the top of the cyclone are analyzed. The feasibility andreliability of the method are verified by the experimental results.

Reliability of a Novel Cobb Protractor for Measuring the Cobb Angle of Radiograph in Scoliosis

Objective To introduce a novel Cobb protractor and assess its reliability and rapidity for measuring Cobb angle in scoliosis patients. Methods The novel Cobb protractor had two endplate markers. A measurement was performed just to align the two markers to each endplate of the curve. The Cobb angle on the posteroanterior radiographs of 24 patients clinically diagnosed with adolescent idiopathic scoliosis was measured by three orthopedic surgeons with both standard Cobb method and the new technique, and the time of measurement was recorded. Intraclass correlation coefficients(ICCs) were calculated to assess the reliability of the new method. Results The time for a measurement with the new tool was approximately 10 seconds less than the time that used to finish a measurement with the standard method(P<0.05). The overall mean Cobb angle for the major curve of the 24 patients was 47.8°. The mean overall intraobserver and interobserver ICC was 0.971 and 0.971 for the Cobb method group, while the overall intraobserver ICC and the interobserver was 0.985 and 0.979 for the new tool group. Conclusions The novel Cobb protractor could perform quick measurement and measure almost all forms of radiographs. The Cobb protractor might be an ideal instrument to measure the Cobb angle.

Model predictive current control for PMSM driven by three-level inverter based on fractional sliding mode speed observer

Based on the fractional order theory and sliding mode control theory,a model prediction current control(MPCC)strategy based on fractional observer is proposed for the permanent magnet synchronous motor(PMSM)driven by three-level inverter.Compared with the traditional sliding mode speed observer,the observer is very simple and eases to implement.Moreover,the observer reduces the ripple of the motor speed in high frequency range in an efficient way.To reduce the stator current ripple and improve the control performance of the torque and speed,the MPCC strategy is put forward,which can make PMSM MPCC system have better control performance,stronger robustness and good dynamic performance.The simulation results validate the feasibility and effectiveness of the proposed scheme.

Application of fiber Bragg grating sensor network in aluminum reduction tank shell temperature monitoring

A fiber Bragg grating temperature sensor network was designed to implement the real-time health monitoring of the aluminum reduction cell. The heat transfer process was simulated using software ANSYS, and an on-line shell monitoring system was established based on optical sensing technology. According to aluminum reduction cell heat transfer theory, the 2D slice finite element model was developed. The relationship between shell temperature and cell status was discussed. Fiber Bragg grating （FBG） was chosen as the temperature sensor in light of its unique advantages. The accuracy of designed FBG temperature sensors exceeds 2 ~C, and good repeatability was exhibited. An interrogation system with 104 sensors based on VPG （volume phase grating） filter was established. Through the long-term monitoring on running state, the status of the aluminum reduction cell, including security and fatigue life could be acquired and estimated exactly. The obtained results provide the foundation for the production status monitoring and fault diagnosis. Long-term test results show good stability and repeatability which are compatible with electrolysis process.

CHARACTER OF RETROREFLECTOR’S LIGHT FIELD’S ENERGY DISTRIBUTION AND ITS MEASURING TECHNOLOGY

The formation of the retroreflected light field is introduced in the paper and the components of the retroreflected light field are analyzed.Furthermore,a deep analysis of the factors affecting energy distribution of the retroreflected light,such as design deviation,angle of incidence,was made.The simulation of the retroreflected light field was done.Recommendation is made in detail on both the energy distribution of the retroreflected light field at different working distances and the energy distribution of the retroreflected light field at a short distance when the diverging light comes.At last,two kinds of measuring instrument for the retroreflector are introduced,one is the long tunnel measuring instrument,the other is the minitype measuring instrument based on the character of the retroreflector when the diverging light comes.

Distributed Optical Fiber Sensor for Multi-point Temperature Measurement

The distributed optical fiber sensing technology is overviewed,which is based on Raman scattering light theory.Basic operation principle,structure,system characteristics and signal processing are discussed.This structure and method of the signal processing possess of certain spatial resolution,hence will ensure the practicability of system.

Limnological instrumentation in the middle of the 19^(th) century:the first temperature and density profiles measured in the Dead Sea

The first modem survey of the Dead Sea was performed by the Geological Survey of Israel in 1959-1960, and the report published remains the baseline study for our understanding of the physical and chemical properties of the lake. At the time the Dead Sea was a meromictic lake with a strong salinity gradient separating the deep waters （〉40 m depth） from the less saline surface waters. A few results of analyses of deeper water samples collected in the 1930s were reported, but overall we have very little information about the structure of the lake＇s water column before the 1959-1960 survey. However, it is little known that data on the physical and the chemical structure of the Dead Sea water column were obtained already in the middle of the 19~ century, and the information collected then is highly relevant for the reconstruction of the limnological properties of the lake in earlier times. The expedition of Lieutenant William Lynch （U.S. Navy） in 1848 reported the presence of a temperature minimum at a depth of-18 m, and also retrieved a water sample collected close to the bottom for chemical analysis. In 1864, the French Dead Sea exploration by the Duc de Luynes and his crew yielded detailed density and salinity profiles for a number of sampling stations. The results of these pioneering studies are discussed here, as well as the sampling equipment and measuring instruments used by the 1848 and the 1864 expeditions.

Identifying Anomaly Aircraft Trajectories in Terminal Areas Based on Deep Autoencoder and Its Application in Trajectory Clustering

Anomalous trajectory detection and traffic flow classification for complicated airspace are of vital importance to safety and efficiency analysis.Some researchers employed density-based unsupervised machine learning method to exploit these trajectories related to air traffic control(ATC)actions.However,the quality of position data and the tiny density difference between traffic flows in the terminal area make it particularly challenging.To alleviate these two challenges,this paper proposes a novel framework which combines robust deep auto-encoder(RDAE)model and density peak(DP)clustering algorithm.Specifically,the RDAE model is utilized to reconstruct denoising trajectory and identify anomaly trajectories in the terminal area by two different regularizations.Then,the nonlinear components captured by the encoder of RDAE are input in the DP algorithm to classify the global traffic flows.An experiment on a terminal airspace at Guangzhou Baiyun Airport(ZGGG)with anomaly label shows that the proposed combination can automatically capture non-conventional spatiotemporal traffic patterns in the aircraft movement.The superiority of RDAE and combination are also demonstrated by visualizing and quantitatively evaluating the experimental results.