农业开发项目财务评价方法有待完善

农业是第一产业，也是一个弱质产业，处于产业链最基础、最低级的位置，从理论上讲，农业开发项目的投资收益率应该低于二、三产业。但从目前情况看，我国农业开发项目(如世行二期项目)的投资报酬率一般在30％以上，投资回收期一般3～4年，有的甚至更短。这种现象是不符合实际的。

Identification of abnormal movement state and avoidance strategy for mobile robots

Abnormal movement states for a mobile robot were identified by four multi-layer perceptron. In the presence ot abnormality, avoidance strategies were designed to guarantee the safety of the robot. Firstly, the kinematics of the normal and abnormal movement states were exploited, 8 kinds of features were extracted. Secondly, 4 multi-layer pereeptrons were employed to classify the features for four 4-driving wheels into 4 kinds of states, i.e. normal, blocked, deadly blocked, and slipping. Finally, avoidance strategies were designed based on this. Experiment results show that the methods can identify most abnormal movement states and avoid the abnormality correctly and timely.

Scheduling deteriorating jobs with rejection on dominant machines

The permutation flow shop scheduling problems with deteriorating jobs and rejection on dominant machines were studied.The objectives are to minimize the makespan of scheduled jobs plus the total rejection penalty and the total completion time of scheduled jobs plus the total rejection penalty.For each objective, polynomial time algorithms based on dynamic programming were presented.

Road traffic states estimation algorithm based on matching of regional traffic attracters

To effectively solve the traffic data problems such as data invalidation in the process of the acquisition of road traffic states,a road traffic states estimation algorithm based on matching of the regional traffic attracters was proposed in this work.First of all,the road traffic running states were divided into several different modes.The concept of the regional traffic attracters of the target link was put forward for effective matching.Then,the reference sequences of characteristics of traffic running states with the contents of the target link's traffic running states and regional traffic attracters under different modes were established.In addition,the current and historical regional traffic attracters of the target link were matched through certain matching rules,and the historical traffic running states of the target link corresponding to the optimal matching were selected as the initial recovery data,which were processed with Kalman filter to obtain the final recovery data.Finally,some typical expressways in Beijing were adopted for the verification of this road traffic states estimation algorithm.The results prove that this traffic states estimation approach based on matching of the regional traffic attracters is feasible and can achieve a high accuracy.

Experimental Simulation and Analysis of the Yarn Motion Track in a Hairiness-Reducing Nozzle

A visible magnified and simulated nozzle was designed and installed on a winding machine according to the similarity principle of Reynolds number, to study the yarn motion track in hairiness-reducing nozzle. High-speed photography was used to observe the yam instantaneous motion state in the nozzle. The results show that the yarn motion track seems to be a cylindrical helix which is close to inner wall in the twisting chamber and kept the same with different technical parameters, such as diameter of the twisting chamber and jet pressure in orifices. According to simulation results and reasonable simplification, the motion track equation and the rotational equation of the yarn could be derived. The velocity of the swirl and hairiness is faster than that of the yarn balloon, so there is enough time for hairiness to be wrapped into the main body of yarn and hence the hairiness is reduced.

Monitoring the Morphology of the Bottom of Streams and Reservoirs Using Electrical Impedance Spectrometry Method

A part of the Earth＇s surface has been formed by the action of running water during geomorphological development. The flow of water is one of the ways of how particles can be eroded, transported and accumulated. If endogenous processes do not work, the surface of the continents would lower to the level close to the ocean surface and the relief would have almost no ruggedness. Recently, there have been talks about the relative classification of deviation of the present state from the ＂original＂ or ＂natural＂ one caused by anthropogeneous effects. The activity of man can manifest itself by pollution, the excessive use of water, a change in the flow regime, and the like. Research into the morphology of the river bottom and the bottom of settling tanks or dam reservoirs is systematically carried out in selected streams and reservoirs by the long-term sampling of bottom sediments. The knowledge of the sediment layer is also important. The EIS method, which was used for measuring, is new for the aforementioned applications. Possibilities of EIS method with new apparatus using for this application were tested in laboratory and in situ. On the basis of interpretation of the electrical conductivity data, a grid of depth data was acquired. These data are characterized by anomalously high and low ＂spots＂ and show morphological changes in the studied area.

Structure reliability analysis based on supercavity vehicle steady motion

Taking the steady motion status as a starting point,according to the modeling of actual state of theoretical analysis,a predigested model of supercavity vehicle was established,and relationship expressions of these angles were obtained when the movement of supercavity vehicle was stable.A theoretical analysis on the stability of underwater high-speed movement in the movement simulation program was conducted and the simulation results were given.Then the force status of the supercavity vehicle was elicited from the results.The finite element analysis was carried out based on the stability at all angles obtained from simulation results.Taking a pilot model as example,the Monte Carlo method was adopting to analyze the reliability with the given state of force and displacement.The result indicates that this method is feasible.

Gait fitting for snake robots with binary actuators

Thanks to the special physical architectures and various locomotion gaits,snake robots may offer significant benefits over traditional legged or wheeled locomotion designs in vast types of scenarios.This paper proposes an innovative snake robot with digitally-actuated Stewart platforms as its modules and mainly focuses on the simulations of various snake gaits.Three categories of fitting algorithms are elaborated in simulations of lateral undulation and Configuration-Fitting Algorithm of Four Modules is demonstrated as a universal gait fitting algorithm for all kinds of snake robots with binary actuators.Several typical snake gaits are simulated and the results demonstrate the excellent mobility of the snake robot.

Therapeutic observation of manipulation plus exercise therapy in treating upper crossed syndrome postures of primary school students

Objective:To observe the therapeutic efficacy of sinew-bone balancing manipulation plus exercise therapy in treating postures of primary school students with upper crossed syndrome(UCS).Methods:Sixty pupils with UCS were divided into an exercise group and a combination group using the random number table method,with 30 cases in each group.The combination group received treatments of sinew-bone balancing manipulation plus exercise therapy,while the exercise group received exercise therapy alone.The two groups received interventions once every other day,for a total of 1 month.The sagittal static posture assessment total score,forward head angle(FHA)and forward shoulder angle(FSA)were compared before and after treatment;the sagittal static assessment total score,FHA and FSA were compared between the exercise group and the combination group.Results:Before treatment,there were no significant differences comparing the sagittal static posture assessment total score,FHA and FSA between the two groups(all P>0.05);after treatment,the sagittal static posture assessment total score,FHA and FSA decreased in the two groups,with intra-group statistical significance(all P<0.01),and were lower in the combination group than in the exercise group,with inter-group statistical significance(all P<0.01).Conclusion:Sinew-bone balancing manipulation plus exercise therapy can notably improve the FHA and FSA and reduce the sagittal static posture total score in pupils with UCS,so as to correct the bad postures and adjust UCS physique.It can produce more significant efficacy compared with exercise therapy alone.

Vibration test condition for spacecraft lift-off environment

The purpose of the vibration test of spacecrafts is to assess their adaptability to low-frequency vibration environment during lift-off.This paper gives the simulation of the satellite ground vibration test(GVT) and the state of the satellite along with rocket during lift-off.The simulation results of these two states are compared on condition that the lateral vibration of satellite/launching vehicle(S/LV) interface is the same.It is shown that the dynamic responses of satellite vertex are totally different.This is because there is angular motion of S/LV interface during lift-off,but in the GVT,the angular motion is restrained.By means of numerical simulation of the lift-off state,the angular motion related to the translation motion of S/LV interface can be determined.Then,using this angular motion as supplementary condition to simulate the vibration test,the calculated dynamic responses of satellite vertex are identical with the lift-off state.It demonstrates that supplementing angular motion condition is an effective method to improve spacecraft ground vibration test more identically with the real lift-off environment.Furthermore,it is useful for the application of the multi-degree-of-freedom shaking table,and provides the basis for test condition requirement.

Dynamic Modeling and Active Control of a Strap-on Launch Vehicle

Dynamic modeling and active control of a strap-on launch vehicle are studied in this paper. In the dynamic modeling, the double-compatible free-interface modal synthesis method is used to establish dynamic model of the system, and its model precision is compared with those of finite element method(FEM), fixedinterface modal synthesis method and free-interface modal synthesis method. In the active control, the swing angle of rocket motor is used as design variable, and the control law design based on the model of mass center motion is adopted to validate the system. Simulation results indicate that the double-compatible model synthesis method can properly approximate the FEM which is used as the benchmark solution, and the model precision of the double-compatible modal synthesis method is obviously higher than those of the fixed-interface and freeinterface modal synthesis methods. Based on the control law design, the deflection of mass center of the launch vehicle is very small.

Bi-dimension decomposed hidden Markov models for multi-person activity recognition

We present a novel model for recognizing long-term complex activities involving multiple persons. The proposed model, named ‘decomposed hidden Markov model’ (DHMM), combines spatial decomposition and hierarchical abstraction to capture multi-modal, long-term dependent and multi-scale characteristics of activities. Decomposition in space and time offers conceptual advantages of compaction and clarity, and greatly reduces the size of state space as well as the number of parameters. DHMMs are efficient even when the number of persons is variable. We also introduce an efficient approximation algorithm for inference and parameter estimation. Experiments on multi-person activities and multi-modal individual activities demonstrate that DHMMs are more efficient and reliable than familiar models, such as coupled HMMs, hierarchical HMMs, and multi-observation HMMs.