共查询到20条相似文献，搜索用时 171 毫秒
1.
It is predicted that there will be 5 scientific breakthroughs in the 21st century.We'll know where we came from. Why does the universe exist?To put it another way, why is there something instead of nothing?Since the 1920s, scientists have known the universe is expanding, which means it must have started at a definite time in the past. They even have developed theories that give a detailed picture of the evolution of the universe from the time it was a fraction of a second old to the present. Over the next couple of decades, these theories will be refined by data from extraordinary powerful new telescope. We will have a better understanding of how matter behaves at the unfathomably high temperatures and pressures of the early universe. 相似文献
2.
The construction of the cables is a key step for erecting suspen-dome structures. In practical engineering, it is difficult to ensure that the designed pre-stresses of cables have been exactly introduced into the structures in the site; so it is necessary to evaluate the influence of the variation of the pre-stresses on the structural behavior. In the present work, an orthogonal design method was employed to investigate the pre-stressed cables' sensitivity to the suspen-dome system. The investigation was concentrated on a Kiewitt suspen-dome. Parametric studies were carried out to study the sensitivity of the structure's static behavior, dynamic behavior, and buckling loads when the pre-stresses in the cables varied. The investigation indicated that suspen-dome structures are sensitive to the pre-stresses in all cables; and that the sensitivity depended on the location of the cables and the kind of structural behavior. Useful suggestions are given at the end of the paper. 相似文献
3.
《海外英语》2003,(12):15
A high-speed land and water vehicle which transforms from sleek sports car to jet-propelled boat at the touch of a button made waves at its unveiling.The Aquada is designed to reach speeds of 100 miles per hour on land and over 30 mph on water, according to Gibbs Technology, which developed the new technology. 相似文献
4.
Edgar Scavino Dzuraidah Abdul Wahab Aini Hussain Hassan Basri Mohd Marzuki Mustafa 《浙江大学学报(A卷英文版)》2009,10(6):794-799
An experimental machine vision apparatus was used to identify and extract recyclable plastic bottles out of a conveyor belt. Color images were taken with a commercially available Webcam, and the recognition was performed by our homemade software, based on the shape and dimensions of object images. The software was able to manage multiple bottles in a single image and was additionally extended to cases involving touching bottles. The identification was fulfilled by comparing the set of measured features with an existing database and meanwhile integrating various recognition techniques such as minimum distance in the feature space, self-organized maps, and neural networks. The recognition system was tested on a set of 50 different bottles and provided so far an accuracy of about 97% on bottle identification. The extraction of the bottles was performed by means of a pneumatic arm, which was activated according to the plastic type; polyethylene-terephthalate （PET） bottles were left on the conveyor belt, while non-PET bottles were extracted. The software was designed to provide the best compromise between reliability and speed for real-time applications in view of the commercialization of the system at existing recycling plants. 相似文献
5.
XinHuangMA 《广西大学梧州分校学报》2004,(1):43-48
This paper evaluates a reading test designed as the final examination of some third year secondary school students in Singapore. Based on the data, histogram is made to illustrate the distribution of different marks among the candidates. The paper then proceeds on to discuss the reliability and validity of the test. Problems affecting the validity of the test are pointed out and improvements are suggested. 相似文献
6.
We propose a new design scheme for a Booth encoder based on clocked transmission gate adiabatic logic （CTGAL）. In the new design the structural complexity of the Booth encoder is reduced while the speed of the multiplier is improved. The adiabatic two＇s complement multiplier-accumulator （MAC） is furthermore a design based on the CTGAL. The computer simulation results indicate that the designed circuit has the correct logic function and remarkably less energy consumption compared to that of the MAC based on complementary metal oxide semiconductor （CMOS） logic. 相似文献
7.
Deok-Soo KIM 《浙江大学学报(A卷英文版)》2006,7(9):I0001-I0002
The Second China-Korea Joint Conference on Geometric and Visual Computing (CKJC 2006) was held during August 23-25, 2006, in Hangzhou, China. CKJC 2006 is an annual conference between China and Korea on Geometric and Visual Computing through a series of discussions and collaborations. The annual conference is a great platform to facilitate the communication and cooperation among the engineers and scientists in Far East region and is designed to address the hottest topics in geometric… 相似文献
8.
BONCIAndrea LONGHISauro MONTERIUAndrea VACCARINIMassimo 《浙江大学学报(A卷英文版)》2005,6(2):110-117
Recent results on the development of a navigation system for a smart wheelchair are presented in this paper. In order to reduce the development cost, a modular solution is designed by using commercial and low cost devices. The functionalities of the tracking control system are described. Experimental results of the proposed assistive system are also presented and discussed. 相似文献
9.
The design methods of anode and cathode are proposed for precision profile grinding.Based on the electrolytic machining theory, electrolytic equilibrium condition and Faraday‘s law of electrolysis are applied to establishing the mathematical model of profile diamond dressing processes. A finite element method (FEM) program is developed to solve the inverse boundary problem of Laplace‘s equation. Desired anode contour or cathode shape is determined by computing the distribution of electric potential layer by layer. Electrolytic machining experiment is carried out to verify the simulated anode shape. The research result shows that shape deviation between designed cathode and profile wheel increases with the value of angle between feed rate and the normal to anode surface. The shape of simulated anode is consistent with the contour of metal-bonded diamond profile wheel for a given cathode. Based on the anode contour, cathode shape can also be designed accurately. 相似文献
10.
Zhi-hua Gan Guo-jun Liu Ying-zhe Wu Qiang Cao Li-min Qiu Guo-bang Chen J. M. Pfotenhauer 《浙江大学学报(A卷英文版)》2008,9(9):1277-1282
A single stage Stifling pulse tube cryocooler was designed based on REGEN 3.2 and fabricated for testing. The experimental results show that the cooler can provide a cooling capacity of 5.0 W at 79.1 K, and produce a no-load temperature of 57.0 K, operating with an average pressure of 2.50 MPa and a frequency of 60 Hz, performance results that are very close to the calculated values. The cryocooler can be cooled from room temperature to 80 K in 8.5 min. The fast cooldown time is a result of the small regenerator. 相似文献
11.
To analyze the use of upper limb support during paraplegic walking assisted by functional electrical stimulation （ FES）. a new dynamical measurement for handle reaction vector （HRV） applied by patient to walker was proposed. To avoid the discomfort of direct monitoring, the dynamometer system was designed based on 12 string-gauge bridges instrumented on a standard walker frame. The detailed positions of these bridges were determined according to the deformation distributions of the walker frame under different directional components of HRV. To adapt the system to quantitative and reliable measurement, a redundant-optimized technique was developed in calibration. The measurement accuracy, nonlinearity, and crosstalk of the designed system were investigated, which were better than 1.01%. 2.91%. and 3. 19% respectively. Clinical trials were done with 6 paraplegic subjects using the system and one case was given as the example of actual measurement. All experiment and clinical trial results show that this method is reliable and practicable. 相似文献
12.
Bin Chen Sheng-xiang Xiao Peng-cheng Gu Xiang-jin Lin 《Journal of Zhejiang University. Science. B》2010,11(9):673-680
Objective:In order to achieve accurate implantation of the acetabular prosthesis in total hip arthroplasty(THA),we designed individual templates based on a three-dimensional(3D) model generated from computed tomography(CT) scans.Methods:Individual templates were designed for 12 patients who underwent THA.A physical template was designed to conform to the contours of the patient's acetabulum and to confirm the rotation of the acetabular center.This guided the acetabular component orientation.Results:The preoperative and postoperative X-ray and CT scans were obtained to assess the location with respect to the accuracy of the acetabular component.For all patients,the abduction angle of the acetabular component was 46.7°o 54.3°and the anteversion angle was 11.3°to 18.5°.Conclusions:The assessment of postoperative CT scans demonstrated higher accuracy of the acetabular component bore when used with the individual template.Therefore,the individual template can be an alternative to the computer-assisted navigation systems,with a good cost-performance ratio. 相似文献
13.
《教学考试》2024,(12):66-67
<正>七选五人与社会体裁：说明文词数：266 China’s Five-hundred-meter Aperture Spherical Radio Telescope, known as FAST, is the world’s most sensitive listening device. The single-dish radio telescope is made of 4 450 individual panels that scan the sky, detecting the universe’s whispers and shouts. 相似文献
14.
Safia Abbas Hajime Sawamura 《美中教育评论》2010,7(9):58-67
This paper presents the development of an Argument-Learning System （ALES）. The idea is based on the AIF （argumentation interchange format） ontology using ＂Walton theory＂. ALES uses different mining techniques to manage a highly structured arguments repository. This repository was designed, developed and implemented by the authors. The aim is to extend the previous framework proposed by developing an intelligent tutoring environment for argument learning that aims to： （1） guide the students during argument learning; （2） aid in improving the students＇ argument skills; and （3） offer an argument classifier agent that retrieves the most relevant results to the subject of search. This paper focuses on the environment development specifying the status of each of the constituent modules. 相似文献
15.
Kevin H. Ashford-Rowe Marnie Holt 《美中教育评论》2011,(3):317-322
The ＂emerging educational institutional decision-making matrix＂ is developed to allow educational institutions to adopt a rigorous and consistent methodology of determining which of the myriad of emerging educational technologies will be the most compelling for the institution, particularly ensuring that it is the educational or pedagogical but not the technological imperative that drives the technology integration agenda. The matrix is designed to be used after some initial research into an emerging technology. Once a technology is put through the matrix, a member of options are available： （1） shelving the technology; （2） putting the technology on hold and maintaining a watching brief until the technology matures in the market; and （3） researching the product further by conducting a trial or placing in testing sandpit. After further research, the technology can be tested as a pilot to determine how well or otherwise, the technology works within the institution. If an emerging technology has more than one product associated with it, a second and third step in the matrix has been developed, and the second step assigns a rating to each of the categories within the matrix. With many products containing similar features, a third step has been developed to compare products on a feature level. 相似文献
16.
The current method to solve the problem of active suspension control for a vehicle is often dealt with a quarter-car or half-car model.But it is not enough to use this kind of model for practical applications.In this paper,based on considering the influence of factors such as,seat and passengers a MDOF(multi-degree-of-freedom)model describing the vehicle motion is set up.The MODF model,which is 8DOF of four independent suspensions and four wheel tracks,is more applicable by comparison of its analysis result with some conventional vehicle models.Therefore,it is more suitable to use the 8DOF full-car model than a conventional 4DOF half-car model in the active control design for car vibration.Based on the derived 8DOF odel,a controller is designed by using LQ(linear quadratic)control theory,and the appropriate control scheme is selected by testing various performance indexes.Computer simulation 8is carried out for a passenger car running on a road with step disturbance and random road disturbance expressed by Power Spectral Density(PSD).Vibrations corresponding to ride comfort are derived under the foregoing road disturbances.The response results for uncontrolled and controlled system are compared.The response of vehicle vibration is greatly suppressed and quickly damped.which testifies the effect of the active suspenson.The results achieved for various controllers are compared to invesigate the influence of different control schemes on the control effect. 相似文献
17.
As one of the best-known literary works of the American novelist Ursula K.Le Guin,The Left Hand of Darkness is not only successful in its splendid plots and beautiful language but also in the important function of its readers in reading.In the thesis,one of its themes,coexistence of opposites,is analyzed in the reader response perspective in order to reveal Le Guin’s reader-consciousness.The theme exists on a higher level in the novel and expresses Le Guin’s attitude towards life and universe.Le Guin unified her own philosophy in the novel and tried to call for the reader’s resonance. 相似文献
18.
HAN Dong 《重庆大学学报(英文版)》2015,14(2):63-72
The method to design sliding-mode observers for systems with unknown inputs and measurement disturbances is presented in the paper. An augmented system is constructed by viewing the measurement disturbances as unknow inputs. For such an augmented system, the so-called observer matching condition is not satisfied. Based on the construction of auxiliary outputs, the observer matching condition may be satisfied. High-order sliding-mode differentiators are developed to obtain the estimates of those unmeasurable variables contained in the auxiliary output vector. Employing the estimate of auxiliary output vector, a sliding-mode observer is designed. The simulation results to a real model show that the proposed method is effective. 相似文献
19.
In the paper the author demonstrates how to incorporate communicative interaction in oral tests.To change the passive situation of conducting oral test,an interactive approach is designed and conducted.The design of the test is based on the belief:English oral test is by no means a simple evaluating process,but it can also provide a platform for teacher-student /studentstudent interaction. 相似文献
20.
In autonomous underwater vehicles(AUVs) the onboard power used to complete missions is limited.To solve this problem,a landing AUV has been designed,which conserves energy by sitting on the seafloor while monitoring the ocean.In order to study the dynamic behaviors for better control of the AUV,the dynamic analysis of the landing AUV is presented in this paper.Based on the momentum theorem and the angular momentum theorem,the dynamic model of the landing AUV is derived.The simulations of rectilinear motion,rotary motion and helix motion indicate the dynamic behaviors of the AUV.The ocean experiments validate the dynamic model presented in this paper.The experiments also verify that the landing AUV can work for a longer time than common AUVs. 相似文献