DYNAMIC VARIATIONS OF WATER QUALITY IN TAIHU LAKE AND MULTIVARIATE ANALYSIS OF ITS INFLUENTIAL FACTORS

Dynamic variation of water quality in Meiliang Bay and part of West Taihu Lake has been analysed based on data from 1991 to 1992. Principal Component Analysis is used to reveal the mutual relationships of various factors. It is shown that there existis an obvious spatial and temporal variation in the main factors of water quality. Annual values of TP, CON, TN, Chl-a and conductivity decrease evidently from inner Meiliang Bay to the outer from north to south. TP and TN fluctuate seasonally with much higher value in winter. This is particularly true for the mouth of Liangxi River. In addition, the Chl-1 has a synchronous variation with water temperature, although being lagged a little, and closely relates to TP and TN. Finally, the results from Principal Component Analysis show that TP, TN, SS (or SD), water temperature and Chl-a are the most influential factors to water qualuty in this area, and both suspensions and algae can contribute to transparency to Taihu Lake.

Numerical analysis of dynamic variation of weld pool geometry in fully-penetrated TIG welding

A mathematical model is developed for numerical analysis of thermal process in TIG welding with a moving arc, which is considered the double-elliptic distribution for both arc heat flux and arc pressure. An adjusting factor is introduced into the expression of arc pressure. The domain within which the arc heat flux is distributed non-symmetrically due to arc moving is selected appropriately, and three conditions for the domain to meet are described. The latent heat is taken into consideration by liquid fraction method. The dynamic development of weld pool geometry during TIG welding is analyzed numerically, and the effect of arc moving on the weld pool geometry is discussed. The experimental results show that the numerical analysis accuracy is obviously improved through taking the above-mentioned measures.

Dynamic Variations and Influencing Factors of Groundwater Levels in Lhasa City

This paper focuses on the dynamic variation of groundwater level in Lhasacity. According to the data, the obvious characteristic of the groundwater level of the city is thatit is changing seasonally. Lhasa is divided into three districts according to hydrogeologicalconditions: the alluvial plain of the Lhasa-river, the alluvial plain of the Doilung-river, and thealluvial fan of inter mountain, which presents a downward trend, a slight upward trend and basicallystabilizing trend over the years individually. The analysis indicates that meteorological andhydrological factors lead to the obvious dynamic change of the groundwater level. However, more andmore human activities and over-exploitation of the groundwater cause the downward trend inthegroundwater level.

Dynamic Variation Characteristics of Phosphorus in Paddy Field Runoff in Saline Land and Its Potential Environmental Effect

[Objective] The aim was to study the dynamic variation characteristics of phosphorus in paddy field runoff in saline land and its potential environmental effect. [Method] Taking Qianguo irrigation district in soda-saline land in Songnen Plain as study object, the dynamic variation law of phosphorus in paddy field runoff under different irrigation conditions and its potential environmental effect were discussed. [Result] Surface water in paddy field was alkaline, and scattered soil had poor fertilizer conservation capacity. Phosphorus accumulated in soil surface, which could increase the risk of phosphorus loss. Phosphorus loss in paddy field mainly occurred in irrigation period and runoff period caused by rainstorm. The concentration of total phosphorus (TP), particulate phosphorus (PP), total dissolved phosphorus (TDP) and dissolved reactive phosphorus (DRP) in paddy field runoff decreased with time, especially PP. Phosphorus concentration exceeded critical value and resulted to eutrophication, which threatened the water quality security of Chagan Lake. Phosphorus concentration in water recession canal increased with time, and eutrophication with different degrees appeared under high temperature. TP concentration in surface water of paddy field was highly negatively correlated with that in water recession canal, and the correlation coefficients R2(α=0.05)in three paddy fields were 0.850 9, 0.896 4 and 0.915 3, respectively. The pollution load of phosphorus in paddy field with the best irrigation condition was higher, and its pollution risk was the highest. Thus, such fields should be monitored and controlled mainly as the critical source area of phosphorus loss. [Conclusion] The study could provide theoretical foundations for developing saline land rationally, establishing optimal management measure of phosphorus in saline land and controlling phosphorus loss from farmland to protect local water resources.

Dynamic variation of ambient shear stress field before and after three strong earthquakes in Yunnan

A method calculating relative shear stress values in seismic source areas using data of seismic wave is used in thispaper which is introduced by PEI-SHAN CHEN, based on a rupture model studying seismic rupture process fromtheory of fracture mechanics. The shear stress values τ0 in mid-small earthquakes occurred in 1986~June of 1997in Yunnan and its adjacent areas are used to trace the variation process of ambient shear stress field before andafter three strong earthquakes in Yunnan and China-Myanmar border areas. The results show that there exists abackground of high values in ambient shear stress field. In the development process of a strong earthquake, theambient shear stress field in and nearby its potential source area increases obviously, for a long time, experiences aprocess of multiple down - up - down - up. The pattern of dynamic variation of ambient shear stress field hasreflected the multi-source fields of seismogenesis in and nearby Yunnan. There exist multi-increased areas of ambient shear slress fields synchronously in southwest, northwest. west and east of Yunnan, and three strong eathquakes of magnitude about 7 occurred in the most obviously increased areas of ambient shear stress fields.

Dynamic Variation of Land-use Types of the Constructed Wetland before and after Oil-field Water Irrigation Based on 3S Technology

[Objective] The study aimed at analyzing the dynamic variation of land-use types of the constructed wetland before and after oil-field water irrigation based on 3S technology. [Method] At semi-arid and arid areas in the west of Jilin Province, water resource balance between the amount of oil-field water supply and ecological water requirement in the constructed wetland irrigated by oil-field water during 2001-2010 was investigated firstly. Afterwards, based on 3S technology, the partition and dynamic variation of land-use types of the constructed wetland before and after oil-field water irrigation in 2001, 2006, 2008 and 2010 were analyzed. [Result] The annual ecological water requirement of the constructed wetland from 2003 to 2010 varied from 1.62×106 to 2.24×106 m3, and the annual amount of oil-field water supply in the region changed from 2.12×106 to 2.84×106 m3, which showed that the supply amount of oil-field water could meet the basic ecological water requirement of the constructed wetland. Meanwhile, compared with 2001, the areas of water region and paddy field in 2010 increased by 2.3 and 10.0 times, and the areas of forest and marsh rose by 40.15% and 29.5.0% respectively. [Conclusion] Water shortage and ecological environment problem of arid and semi-arid areas had been improved by oil-field water irrigation.

Deep soil water infiltration and its dynamic variation in the shifting sandy land of typical deserts in China

Soil moisture is the key resource constraint in arid ecosystems, and has been a focus of research on restoration. However, quantitative studies on the contribution of rainfall to deep soil rainfall infiltration are lacking. In this study, we used the YWB-01 Deep Soil Infiltration Water Recorder which had been invented by ourselves to measure the quantity of rain infiltration into deep soil, 150 cm below ground, in four locations in China: Mu Us Sandy Land and Ulan Buh, Tengger, and Badan Jilin deserts over a 2-year period. We found:(1) Deep soil rainfall infiltration decreased progressively from east to west and from semiarid to arid areas, with two locations completely lacking rainfall infiltration. Heavy rain was important to deep soil infiltration in shifting sandy land of arid and semiarid areas.(2) Seasonal variation of infiltration was correlated with rainfall, with a time lag that was less apparent in areas with more rainfall.(3) For single intense rainfall events, infiltration maximums occurred 40–55 h after the rainfall, during which the infiltration rates increased rapidly before reaching a peak, and then decreased slowly. Continuous infiltration could last about 150 h. Rainfall infiltration was determined by the combined action of intensity, quantity and duration. Rainfall with low intensity, long duration, and large quantity was most favorable for deep soil infiltration. Our results can be used in water resource assessments and protection during eco-restoration in the arid and semiarid areas in China.

Experimental Simulation on Dynamic Variation of the Permeability of High-Rank Coal Reservoirs

In terms of the coal reservoir permeability of effective stress, coal matrix shrinkage and gas slippage,we conduct the tests of gas permeability under constant confining pressure and effective stress, as well as illustrate the cumulating method of permeability increment caused by the effects of gas slippage and coal matrix shrinkage.The results show that under the constant confining pressure, gas slippage affecting coal permeability changes to effective stress affecting it mainly. The change point increases with the increase of the confining pressure. The gas slippage effect leads to high permeability under low confining pressure, but coal matrix expansion results in the low value as confining and gas pressures increase. Combined with the drainage process of coalbed methane(CBM)well, the permeability is divided into four change stages based on the above analysis about the three effects, which can improve the change regulation understanding. Four stages are the downward phase under effective stress,the conversion phase of effective stress-coal matrix contraction effect(mainly based on effective stress), the rising stage of the effective stress-coal matrix contraction effect(mainly based on coal matrix contraction effect) and the rising phase of coal matrix contraction-slippage effect(mainly based on slippage effect). Permeability of coal reservoir during the process of drainage and production goes through four stages.

Multibody Dynamics Formulations Based on Variational Principle

The formulation of multibody dynamics was studied based on variational principle. The body coonection matrix was introduced to define the connection configuration. The expression for the system kinematics was obtained by using the body connection matrix. From variational principle the general dynamical equations for multibody system were derived and the dynamical equations were given for multibody system subjected to the constraints.

Monitoring of Land-Cover Dynamic Change in Lancangjiang River Cascaded Hydropower Area

The analysis of the 3 stages＇ （1988,1996,2000） variation of land-cover is performed according to Thematic Mapper （TM） and Enhancement Thematic Mapper（ETM） satellite image by combining ground GIS database with GPS field collected data in the area of Xiaowan-Dachaoshan Reservoirs of Lancangjiang River cascaded Hydropower Area. Consequently, the land-cover is divided into five subclasses, namely water, paddy field and wetland, bare dryland and sparse shrub, secondary forest and density forest. The result showed that the areas of bare land, upland and secondary forest decreased in 1988-1996, whereas from 1996 to 2000, water body and density forest keep invariability while the areas of paddy field and wetland, bare dryland and sparse scrub increasing and the area of secondary forest decrease; Features of reciprocal transformation between density forest and other type of land-cover had two points, i.e. secondary forest, bare dryland and sparse shrub converted to density forest; and density forest converted to secondary forest and paddy field and wetland. It reflects the dynamic variation of density forest; the area which slope less than 8° and greater than 15° shows bigger variation, however, less change in 8°-15°.

Activity Tendency and Dynamic Characteristics of Shanxi Fault Zone

The tendency and dynamic characteristics of horizontal movement along the Shanxi fault zone have been analyzed using the data obtained from 6 repeated measurements (1996～2001) in the GPS monitoring network arranged along the Shanxi fault zone. The results indicate: (1) the tendentious activity of the present stage is characterized by a W trending movement along the northern segment of the zone, an E trending movement along the southern segment and counter clockwise differential activity on the whole, but the intensity of the tendentious activity is not high. The tendentious differential movement is only about 3 mm/a in the direction perpendicular to the fault zone from the south to the north, and its stretch in the SN direction is only 1 mm/a and mainly occurs along the north segment of the fault; (2) The azimuth of the principal compressive stress field reflected by the tendentious movement is 72°; (3) The property of annual activity is not the same, even contrary to one another or deviates from the tendentious activity. Therefore, the parameters of the strain field derived from them dont reflect the physical characteristics of the basic stress field. (4) The high frequency movement (yearly) does not only exist but is also complicated by an intensity several times higher than that of the tendentious movement; (5) Obvious differential movements, including strike slip, can not be seen in either in secular activity or annual activity on both sides of any fault. The tendentious movement not only verifies the conjecture of “strong in the south and weak in north”, which is the basic feature forcing the western boundary of the North China area, but it also extends to the hinterland of North China. The fact that there is no obvious differential activity on both sides of the fault might indicate that the differential activity among the intraplate blocks is completed by gradual variation in a certain space, rather than the abrupt change bordered by a fault or narrow stripe zone. The obvious dynamic activity might indicate: (1) there is stress disturbance in the basic stress field; (2) the inhomogeneous or non synchronous variation that appeared in the regional stress and strain fields was due to the different physical property of the medium; (3)the response occurred because of a variety of external variations. The movement in 2001 shows that the Daixian county and its adjacent area might be the boundary segment for the relative differential activity. More attention should be paid here.

Investigation of power-type variational principles in liquid-filled system

Starting from the basic equations of hydrodynamics, the maximum power- type variational principle of the hydrodynamics of viscous fluids was established by Weizang CHIEN in 1984. Through long-term research, it is clarified that the maximum power-type variational principle coincides with the Jourdian principle, which is one of the common principles for analytical mechanics. In the paper, the power-type variational principle is extended to rigid-body dynamics, elasto-dynamics, and rigid-elastic：liquid coupling dynamics. The governing equations of the rigid-elastic-liquid coupling dynamics in the liquid-filled system are obtained by deriving the stationary value conditions. The results show that, with the power-type variational principles studied directly in the state space, some transformations in the time domain space may be omitted in the establishing process, and the rigid-elastic-liqUid coupling dynamics can be easily numerically modeled. Moreover, the analysis of the coupling dynamics in the liquid-filled system in this paper agrees well with the numerical analyses of the coupling dynamics in the liquid-filled system offered in the literatures.

Density Restriction Effects of Reproductive Rate of Rice Brown Planthopper Population in Super Rice Yongyou 6

[ Objective ] The paper was to study the density restriction effects of reproductive rate of rice brown planthopper （BPH） population in super indiea and japonica hybrid rice Yongyou 6. [Method] Different amounts of rice brown planthoppor were released to super indiea and japonica hybrid flee Yongyou 6 during fillering, booting and gain filling stage, respectively. The reproductive rate and variation dynamics of rice brown planthoppor in super rice was also investigated and analyzed. [Result] Tillering stage： the population quantity of rice brown planthoppor during booting and gain filling stage gradually increased with the increasing basal amount of its population during tillering stage; when the population density of rice brown planthopper during grain filling stage reached a certain limit （ 〉 250 head/cluster）, the population density during milking stage showed decrease trend with the increasing of such density; the development of rice brown planthoppor population in super rice Yongyou 6 showed the characteristics of fast in middle and slow in two ends. Booting stage： the development of rice brown planthopper pop- ulation from booting to gain filling stage increased with the increasing basal amount of density, and their correlation during milking stage was not significant; flee brown planthopper population still had high reproduction capacity in the middle and late stage of super rice, which had latent risk on rice yield. Gain filling stage ： when population density of rice brown planthopper 〈 70 head/cluster, the development of it population increased with the increase of basal amount of density, which had great threat to yield. [ Conclusion] The result provided theoretical basis for establishment and improvement of monitoring early warning system, cost-ef- fective control of occurrence and damage of rice brown planthopper, and improvement of the sustained control ability against rice brown planthopper.

Evaluation of infill well pattern based on the dynamic change of reservoirs during coalbed methane development

With the deepening of coalbed methane(CBM)exploration and development,the problem of low gas production has gradually become one of the main factors restricting the development of the CBM industry in China.Reasonable well pattern deployment can improve the productivity of CBM wells and reduce the cost of production,while the reservoir changes of CBM wells play a important role for well pattern infilling.In this study,the dynamic characteristics of the average reservoir pressure(ARP),permeability,and drainage radius during the development process of CBM wells are systematically analyzed,and predicted the production changes of well groups before and after infilling wells in combination with the characteristics of reservoir changes.The results show that the high gas production wells have a larger pressure drop,long drainage radius,and a large increase in permeability.On the contrary,low gas production wells are characterized by small drainage radius,damaged permeability and difficult to recover.The productivity of infilled horizontal wells is predicted for two well groups with different productivity and reservoir dynamic characteristics.After infilling wells,the production of current wells has increased at different degrees.It is predicted that the average gas production of low gas production well group H1 and middle gas production well group H2 will increase 1.64 and 2.09 times respectively after 3000 days production simulation.In addition,the pressure interference between wells has increased significantly,and the overall gas production of the well group has greatly increased.Infill wells can achieve better development results in areas with superior CBM resources,recoverable reservoir permeability,and small drainage radius during the early production process.The research results provide a reference for the later infill adjustment of CBM well patterns in the study area.

Genetic Programming Using Dynamic Population Variation for Computational Efforts Reduction in System Modeling

In this paper,we propose genetic programming(GP) using dynamic population variation(DPV) with four innovations for reducing computational efforts.A new stagnation phase definition and characteristic measure are defined for our DPV.The exponential pivot function is proposed to our DPV method in conjunction with the new stagnation phase definition.An appropriate population variation formula is suggested to accelerate convergence.The efficacy of these innovations in our DPV is examined using six benchmark problems.Comparison among the difierent characteristic measures has been conducted for regression problems and the new proposed measure outperformed other measures.It is proved that our DPV has the capacity to provide solutions at a lower computational effort compared with previously proposed DPV methods and standard genetic programming in most cases.Meanwhile,our DPV approach introduced in GP could also rapidly find an excellent solution as well as standard GP in system modeling problems.

Dynamic data packing towards the optimization of QoC and QoS in networked control systems

A class of networked control systems is investigated whose communication network is shared with other applications. The design objective for such a system setting is not only the optimization of the control performance but also the efficient utilization of the communication resources. We observe that at a large time scale the data packet delay in the communication network is roughly varying piecewise constant, which is typically true for data networks like the Internet. Based on this observation, a dynamic data packing scheme is proposed within the recently developed packet-based control framework for networked control systems. As expected this proposed approach achieves a fine balance between the control performance and the communication utilization: the similar control performance can be obtained at dramatically reduced cost of the communication resources. Simulations illustrate the effectiveness of the proposed approach.