This paper further explores the estimating and expressing of dynamic balance constraints using statistical methods in GRAPES-3DVAR(Version GM). Unlike the single-level scheme which only considers the coupling between ...This paper further explores the estimating and expressing of dynamic balance constraints using statistical methods in GRAPES-3DVAR(Version GM). Unlike the single-level scheme which only considers the coupling between mass and wind at one level, the multi-level scheme considers the coupling between their vertical profiles and calculates the balanced mass field at each layer using the rotational wind at all model levels. A reformed ridge regression method is used in the new scheme to avoid the multicollinearity problem and reduce the noises caused by unbalanced mesoscale disturbances. The results of numerical experiments show that the new scheme can get more reasonable vertical mass field, reduce the magnitude of the adjustment by the initialization, and improve the potential temperature analysis performance. Furthermore, the results of forecast verification in January(winter) and July(summer) both confirm that the new scheme can significantly improve the temperature forecast accuracy and bring slight positive effects to the pressure and wind forecast.展开更多
The basic structure of epicyclical gear transmission with inner teeth ofsingle-ring, double-ring, three-ring and four-ring reducer are analyzed. The force analysis model ofring reducer is built. Following this, it is ...The basic structure of epicyclical gear transmission with inner teeth ofsingle-ring, double-ring, three-ring and four-ring reducer are analyzed. The force analysis model ofring reducer is built. Following this, it is concluded that the present ring reducer~ have theproblem that the inertia force or the inertia moment is lopsided. On the base of analysis andcalculation the balanced ring reducer which can realize the balance of inertia force and inertiamoment is brought forward, and so is its concrete realizing step. The specimen of the balanced ringreducer is designed and manufactured; the experiment is carried out on the gear transmission testbench. Compared with other ring reducer of the same power, the balanced ring reducer has manyadvantages, such as low vibration noise, low cost and less production difficulty and less heat. Itis the substitute of other ring reducer of the same kind. Therefore, it has important theoreticsignificance and highly practical engineering value.展开更多
Phosphorus(P) is an important macronutrient for plant but can also cause potential environmental risk. In this paper, we studied the long-term fertilizer experiment(started 1980) to assess the soil P dynamic, bala...Phosphorus(P) is an important macronutrient for plant but can also cause potential environmental risk. In this paper, we studied the long-term fertilizer experiment(started 1980) to assess the soil P dynamic, balance, critical P value and the crop yield response in Taihu Lake region, China. To avoid the effect of nitrogen(N) and potassium(K), only the following treatments were chosen for subsequent discussion, including: C0(control treatment without any fertilizer or organic manure), CNK treatment(mineral N and K only), CNPK(balanced fertilization with mineral N, P and K), MNK(integrated organic manure and mineral N and K), and MNPK(organic manure plus balanced fertilization). The results revealed that the response of wheat yield was more sensitive than rice, and no significant differences of crop yield had been detected among MNK, CNPK and MNPK until 2013. Dynamic and balance of soil total P(TP) and Olsen-P showed soil TP pool was enlarged significantly over consistent fertilization. However, the diminishing marginal utility of soil Olsen-P was also found, indicating that high-level P application in the present condition could not increase soil Olsen-P contents anymore. Linear-linear and Mitscherlich models were used to estimate the critical value of Olsen-P for crops. The average critical P value for rice and wheat was 3.40 and 4.08 mg kg^(–1), respectively. The smaller critical P value than in uplands indicated a stronger ability of P supply for crops in this paddy soil. We concluded that no more mineral P should be applied in rice-wheat system in Taihu Lake region if soil Olsen-P is higher than the critical P value. The agricultural technique and management referring to activate the plant-available P pool are also considerable, such as integrated use of low-P organic manure with mineral N and K.展开更多
The dynamic balance quality of a rotating object is an important factor to maintain the stability and accuracy for motion. The azimuth of the principal axis of inertia is a major sign of dynamic balance. A usual metho...The dynamic balance quality of a rotating object is an important factor to maintain the stability and accuracy for motion. The azimuth of the principal axis of inertia is a major sign of dynamic balance. A usual method is measuring moment of inertia matrix relative to some base coordinates on a rotary inertia machine so as to calculate the azimuth of principal axis of inertia, By using the measured unbalance results on the two trimmed planes on a vertical hard bearing double-plane dynamic balancing machine, the dimension and direction of couple unbalance can be found. An azimuth angle formula for the principal axis of inertia is derived and is solved by using unbalance quantities. The experiments indicate that method based on dynamic balancing measurement is proved rational and effective and has a fine precision.展开更多
Flow field in multilayer gob area, which formed in small hiden-depth, multi-coal layer groups, close distance, hard coal layer, and hard roof, possesses characteristics such as complex, changeable and unstable. Dynami...Flow field in multilayer gob area, which formed in small hiden-depth, multi-coal layer groups, close distance, hard coal layer, and hard roof, possesses characteristics such as complex, changeable and unstable. Dynamic balance theory of local flow field in multilayer gob area was built based on the realistic requirement that the serious threat on current mining coal layer by large-scale spontaneous combustion fire on close spontaneous combustion coal layer group of Datong Coal mining area at the 'di-hard' conditions was caused by small coal pit mining. The kernel was in dynamic balance between flow field pressures of working face and local flow field in multilayer gob area was kept by transformation. Corresponding technology and set of devices were developed.展开更多
At age 5,children with trisomy 21 have roughly 2 years of delayed motor development.We aimed to verify if children with trisomy 21(AD)(N=6,7.67±1.51 years)had a similar performance to children with a typical deve...At age 5,children with trisomy 21 have roughly 2 years of delayed motor development.We aimed to verify if children with trisomy 21(AD)(N=6,7.67±1.51 years)had a similar performance to children with a typical development(TD)(N=37,5.19±0.40 years old),in a playful motor action(to spin on herself until she cannot get more).On average,ADs gave less laps,for less time,spending more time per rotation,but without significant difference.Of the AD,one-third fell and rose to continue to spin;one-third stopped and resumed spinning(with intervals of 2.05±0.86s).Three ADs performed the action counterclockwise and the other three in clockwise direction.The results support the hypothesis that AD can perform the activity of spinning,with DT(significantly)younger,allowing to AD momentary pauses and conditions for their physical security.展开更多
To solve the load balancing problem in a triplet-based hierarchical interconnection network(THIN) system, a dynamic load balancing (DLB)algorithm--THINDLBA, which adopts multicast tree (MT)technology to improve ...To solve the load balancing problem in a triplet-based hierarchical interconnection network(THIN) system, a dynamic load balancing (DLB)algorithm--THINDLBA, which adopts multicast tree (MT)technology to improve the efficiency of interchanging load information, is presented. To support the algorithm, a complete set of DLB messages and a schema of maintaining DLB information in each processing node are designed. The load migration request messages from the heavily loaded node (HLN)are spread along an MT whose root is the HLN. And the lightly loaded nodes(LLNs) covered by the MT are the candidate destinations of load migration; the load information interchanged between the LLNs and the HLN can be transmitted along the MT. So the HLN can migrate excess loads out as many as possible during a one time execution of the THINDLBA, and its load state can be improved as quickly as possible. To avoid wrongly transmitted or redundant DLB messages due to MT overlapping, the MT construction is restricted in the design of the THINDLBA. Through experiments, the effectiveness of four DLB algorithms are compared, and the results show that the THINDLBA can effectively decrease the time costs of THIN systems in dealing with large scale computeintensive tasks more than others.展开更多
Mobile Edge Computing(MEC)-based computation offloading is a promising application paradigm for serving large numbers of users with various delay and energy requirements.In this paper,we propose a flexible MECbased re...Mobile Edge Computing(MEC)-based computation offloading is a promising application paradigm for serving large numbers of users with various delay and energy requirements.In this paper,we propose a flexible MECbased requirement-adaptive partial offloading model to accommodate each user's specific preference regarding delay and energy consumption.To address the dimensional differences between time and energy,we introduce two normalized parameters and then derive the computational overhead of processing tasks.Different from existing works,this paper considers practical variations in the user request patterns,and exploits a flexible partial offloading mode to minimize computation overheads subject to tolerable delay,task workload and power constraints.Since the resulting problem is non-convex,we decouple it into two convex subproblems and present an iterative algorithm to obtain a feasible offloading solution.Numerical experiments show that our proposed scheme achieves a significant improvement in computation overheads compared with existing schemes.展开更多
Measurement error of unbalance's vibration response plays a crucial role in calibration and on-line updating of influence coefficient(IC). Focusing on the two problems that the moment estimator of data used in cali...Measurement error of unbalance's vibration response plays a crucial role in calibration and on-line updating of influence coefficient(IC). Focusing on the two problems that the moment estimator of data used in calibration process cannot fulfill the accuracy requirement under small sample and the disturbance of measurement error cannot be effectively suppressed in updating process, an IC calibration and on-line updating method based on hierarchical Bayesian method for automatic dynamic balancing machine was proposed. During calibration process, for the repeatedly-measured data obtained from experiments with different trial weights, according to the fact that measurement error of each sensor had the same statistical characteristics, the joint posterior distribution model for the true values of the vibration response under all trial weights and measurement error was established. During the updating process, information obtained from calibration was regarded as prior information, which was utilized to update the posterior distribution of IC combined with the real-time reference information to implement online updating. Moreover, Gibbs sampling method of Markov Chain Monte Carlo(MCMC) was adopted to obtain the maximum posterior estimation of parameters to be estimated. On the independent developed dynamic balancing testbed, prediction was carried out for multiple groups of data through the proposed method and the traditional method respectively, the result indicated that estimator of influence coefficient obtained through the proposed method had higher accuracy; the proposed updating method more effectively guaranteed the measurement accuracy during the whole producing process, and meantime more reasonably compromised between the sensitivity of IC change and suppression of randomness of vibration response.展开更多
In order to balancing based on data achieve dynamic load flow level, in this paper, we apply SDN technology to the cloud data center, and propose a dynamic load balancing method of cloud center based on SDN. The appro...In order to balancing based on data achieve dynamic load flow level, in this paper, we apply SDN technology to the cloud data center, and propose a dynamic load balancing method of cloud center based on SDN. The approach of using the SDN technology in the current task scheduling flexibility, accomplish real-time monitoring of the service node flow and load condition by the OpenFlow protocol. When the load of system is imbalanced, the controller can allocate globally network resources. What's more, by using dynamic correction, the load of the system is not obvious tilt in the long run. The results of simulation show that this approach can realize and ensure that the load will not tilt over a long period of time, and improve the system throughput.展开更多
A new type of vibration structure (i.e. supporting system, called swing frame cus- tomarily) of vertical dynamic balancing machine has been designed, which is based on an analysis for the swing frame of a traditiona...A new type of vibration structure (i.e. supporting system, called swing frame cus- tomarily) of vertical dynamic balancing machine has been designed, which is based on an analysis for the swing frame of a traditional double-plane vertical dynamic balancing machine. The static unbalance and couple unbalance can be e?ectively separated by using the new dynamic balancing machine with the new swing frame. By building the dynamics model, the advantages of the new structure are discussed in detail. The modal and harmonic response are analyzed by using the ANSYS7.0. By comparing the ?nite element modal analysis with the experimental modal analy- sis, the natural frequencies and vibration modes are found. There are many spring boards in the new swing frame. Their sti?nesses are di?erent and assorted with each other. Furthermore, there are three sensors on the measuring points. Therefore, the new dynamic balancing machine can measure static unbalance and coupling unbalance directly, and the interaction between them is faint. The result shows that the new vertical dynamic balancing machine is suitable for inertial measurement of ?ying objects, and can overcome the shortcomings of traditional double-plane vertical dynamic balancing machines, which the e?ect of plane-separation is inferior. The vertical dynamic balancing machine with the new vibration structure can ?nd wide application in the future. The modelling and analysis of the new vibration structure will provide theoretical basis and practical experience for designing new-type vertical dynamic balancing machines.展开更多
To decrease the cost of exchanging load information among processors, a dynamic load-balancing (DLB) algorithm which adopts multieast tree technology is proposed. The muhieast tree construction rules are also propos...To decrease the cost of exchanging load information among processors, a dynamic load-balancing (DLB) algorithm which adopts multieast tree technology is proposed. The muhieast tree construction rules are also proposed to avoid wrongly transferred or redundant DLB messages due to the overlapping of multicast trees. The proposed DLB algorithm is distributed controlled, sender initiated and can help heavily loaded processors with complete distribution of redundant loads with minimum number of executions. Experiments were executed to compare the effects of the proposed DLB algorithm and other three ones, the results prove the effectivity and practicability of the proposed algorithm in dealing with great scale compute-intensive tasks.展开更多
Unbalanced vibration in dual-rotor rotating machinery was studied with numerical simulations and experiments. A new method is proposed to separate vibration signals of inner and outer rotors for a system with very lit...Unbalanced vibration in dual-rotor rotating machinery was studied with numerical simulations and experiments. A new method is proposed to separate vibration signals of inner and outer rotors for a system with very little difference in rotating speeds. Magnitudes and phase values of unbalance defects can be obtained directly by sampling the vibration signal synchronized with reference signal. The balancing process is completed by the reciprocity influence coefficients of inner and outer rotors method. Results showed the advantage of such method for a dual-rotor system as compared with conventional balancing.展开更多
The rapid growth of interconnected high performance workstations has produced a new computing paradigm called clustered of workstations computing. In these systems load balance problem is a serious impediment to achie...The rapid growth of interconnected high performance workstations has produced a new computing paradigm called clustered of workstations computing. In these systems load balance problem is a serious impediment to achieve good performance. The main concern of this paper is the implementation of dynamic load balancing algorithm, asynchronous Round Robin (ARR), for balancing workload of parallel tree computation depth-first-search algorithm on Cluster of Heterogeneous Workstations (COW) Many algorithms in artificial intelligence and other areas of computer science are based on depth first search in implicitty defined trees. For these algorithms a load-balancing scheme is required, which is able to evenly distribute parts of an irregularly shaped tree over the workstations with minimal interprocessor communication and without prior knowledge of the tree’s shape. For the (ARR) algorithm only minimal interprocessor communication is needed when necessary and it runs under the MPI (Message passing interface) that allows parallel execution on heterogeneous SUN cluster of workstation platform. The program code is written in C language and executed under UNIX operating system (Solaris version).展开更多
This paper proposes a dynamic load balancing with learning model for a Sudoku problem solving system that has multiple workers and multiple solvers.The objective is to minimise the total processing time of problem sol...This paper proposes a dynamic load balancing with learning model for a Sudoku problem solving system that has multiple workers and multiple solvers.The objective is to minimise the total processing time of problem solving.Our load balancing with learning model distributes each Sudoku problem to an appropriate pair of worker and solver when it is received by the system.The information of the estimated solution time for a specific number of given input values,the estimated finishing time of each worker,and the idle status of each worker is used to determine the worker-solver pairs.In addition,the proposed system can estimate the waiting period for each problem.Test results show that the system has shorter processing time than conventional alternatives.展开更多
Influence coefficient method and the modal balancing method are often used in the dynamic balancing in the past days. These methods sometimes exist a lot of big measurement errors. So, in order to make these errors mu...Influence coefficient method and the modal balancing method are often used in the dynamic balancing in the past days. These methods sometimes exist a lot of big measurement errors. So, in order to make these errors much smaller, and to use the vibration information of the rotor more sufficiently, at last, we put forward the full vector dynamic balancing algorithm. Though the theoretical analysis, and the experiment tests, we can compare with the new method and the old method , study the relationship between the dynamic balancing and the rotation equipment, and the direction of the development. The full vector dynamic balancing algorithm theory can be inferred from the Jeffcott rotor. To compare with the methods which are mentioned before, we can find that the full vector dynamic balancing algorithm is much better than the influence coefficient method and the modal balancing method. We can use the MATLAB program to prove that the full vector dynamic balancing algorithm is much better. So the conclusion is completely right.展开更多
Background:Balance impairment is one of the strongest risk factors for falls.Proprioception,cutaneous sensitivity,and muscle strength are 3 important contributors to balance control in older adults.The relationship th...Background:Balance impairment is one of the strongest risk factors for falls.Proprioception,cutaneous sensitivity,and muscle strength are 3 important contributors to balance control in older adults.The relationship that dynamic and static balance control has to proprioception,cutaneous sensitivity,and muscle strength is still unclear.This study was performed to investigate the relationship these contributors have to dynamic and static balance control.Methods:A total of 164 older adults(female=89,left dominant=15,age:73.5±7.8 years,height:161.6±7.1 cm,weight:63.7±8.9 kg,mean±SD)participated in this study.It tested the proprioception of their knee flexion/extension and ankle dorsi/plantarflexion,along with cutaneous sensitivity at the great toe,first and fifth metatarsals,arch,and heel,and the muscle strength of their ankle dorsi/plantarflexion and hip abduction.The Berg Balance Scale(BBS)and the root mean square(RMS)of the center of pressure(CoP)were collected as indications of dynamic and static balance control.A partial correlation was used to determine the relationship between the measured outcomes variables(BBS and CoPRMS)and the proprioception,cutaneous sensitivity,and muscle strength variables.Results:Proprioception of ankle plantarflexion(r=-0.306,p=0.002)and dorsiflexion(r=-0.217,p=0.030),and muscle strength of ankle plantarflexion(r=0.275,p=0.004),dorsiflexion(r=0.369,p<0.001),and hip abduction(r=0.342,p<0.001)were weakly to moderately correlated with BBS.Proprioception of ankle dorsiflexion(r=0.218,p=0.020)and cutaneous sensitivity at the great toe(r=0.231,p=0.041)and arch(r=0.285,p=0.002)were weakly correlated with CoP-RMS in the anteroposterior direction.Proprioception of ankle dorsiflexion(r=0.220,p=0.035),knee flexion(r=0.308,p=0.001)and extension(r=0.193,p=0.040),and cutaneous sensitivity at the arch(r=0.206,p=0.028)were weakly to moderately correlated with CoP-RMS in the mediolateral direction.Conclusion:There is a weak-to-moderate relationship between proprioception and dynamic and static balance control,a weak relationship between cutaneous sensitivity and static balance control,and a weak-to-moderate relationship between muscle strength and dynamic balance control.展开更多
Recovery from stroke needs different time and speed in every case depending on the brain capacity of neural plasticity. Based on neurophysiological researches high repetition of practice is required to induce neuropla...Recovery from stroke needs different time and speed in every case depending on the brain capacity of neural plasticity. Based on neurophysiological researches high repetition of practice is required to induce neuroplastic changes and functional recovery of motor deficits. However, data from earlier studies shows that stroke patients generally perform a very limited number of movement repetitions in traditional therapy sessions. Virtual Reality therapy was found to be beneficial in improving trunk, hand, upper and lower extremity functions. However, reviews found no definitive conclusions regarding balance. The present study focuses on evaluating the efficacy of Nintendo WiiTM on balance and gait functions of stroke patients. Twenty one hemiparetic stroke patients were randomly assigned to either control or therapy groups. Effectiveness was evaluated by Fugl-Meyer balance subtest, Functional Ambulation Categories (FAC), Romberg (R), sharpened Romberg (SR), one-legged stance (OLS), six-meter walking test (6MWT) and timed up and go test (TUG). The analysis revealed a significant effect of training with Nintendo Wii M for FAC z = 0.0267, FMBS z = 0.0046, OLST2 z = 0.0068 and OLS1 z = 0.0067 (affected side). The control group demonstrated improvement in R (z = 0.0474) and SR (z = 0.0411). In both groups improvement was detected in functional mobility and 6MWT (control group z = 0.0069, Wii groupz = 0.0123). No significant differences were found between groups. Findings of the current study support that balance treatment with Nintendo WiiTM is similarly effective method to improve static balance and functional mobility when compared with conventional therapy.展开更多
Proper balance is essential for athletes during competition and training as sport places different balance requirements on the human body. The purpose of the study was to analyze balance performance among female athle...Proper balance is essential for athletes during competition and training as sport places different balance requirements on the human body. The purpose of the study was to analyze balance performance among female athletes using COP (center of pressure) sway parameters. Twenty one NCAA (National Collegiate Athletic Association) division I female athletes (soccer, volleyball and dance) completed the study. Static balance was assessed using UST (unilateral stance test) and dynamic balance was assessed using MCT (motor control test) on the NeuroCom Equitest. Sway velocities, root mean square sway and reaction time latencies were used to quantify balance. A one-way between subjects ANOVA (analysis of variance) was performed to analyze these balance parameters. Significant (p 〈 0.05) differences between groups were found and post hoc comparisons revealed that the volleyball and dance groups had better static balance compared to soccer players, while both soccer and volleyball groups had better dynamic balance compared to the dance group. The results from the study indicate two points: first, differences in balance performance among female athletes in different sporting discipline; second, there is no relationship between static and dynamic balance. This indicates that it may be more beneficial to assess and train for static and dynamic balance individually.展开更多
Aerogels are of great interest in diverse fields including thermal insulation,environmental protection,liquid separation,electromagnetic shielding,etc.However,the development of renewable and recyclable aerogels,espec...Aerogels are of great interest in diverse fields including thermal insulation,environmental protection,liquid separation,electromagnetic shielding,etc.However,the development of renewable and recyclable aerogels,especially synthetic pol-ymer-based ones,remains an enormous challenge,which seriously hinders the practical application of aerogels.Herein,utilizing Kevlar nanofibers(KNFs)as representative synthetic polymer building blocks,a destabilizing dynamic balance(DDB)strategy is proposed to fabricate recyclable aerogels with high reprocessing consistency.More specifically,aprotic esters(e.g.,di-tert-butyl decarbonate,DiBoc)and alkalis(e.g.,potassium tert-butoxide,t-BuOK)are introduced to trigger the destabilizing dynamic balance between deprotonation–protonation of KNFs,resulting in a reversible sol–gel transition.Meanwhile,the duration of sol–gel transition(i.e.,gelation)time,adjustable from 10^(–2)to 10^(3)min,is compatible with versatile processing methods,such as static mould casting,dynamic wet spinning,dynamic blade coating and dynamic 3D printing.These unique advantages enable the fabrication of various KNF aerogel products(i.e.,continuous fibers,continuous films,large-sized monoliths and 3D-printed articles)with low density(33–165 mg/cm3),high compressive modulus(up to 52 MPa),high specific surface area(360–404 m^(2)/g)and low thermal conductivity(0.027–0.050 W/m·K).Notably,these properties are comparable or superior to that of previously reported KNF aerogels and far superior to that of recyclable aerogels.Compared with direct fabrication from raw materials,the DDB strategy reduces the cost by 50.5%and 82.5%when products are made from recycled aerogels and wet gels,respectively.Such cost reduction further increases with the number of recycling cycles,which is calculated as$275 per kilogram KNF aerogel with 5 cycles.This work develops extraordinary KNF aerogels those can be recycled and reused,as well as provides a strategy that can be applied to design more recyclable aerogels.展开更多
基金China Special Fund for Meteorological Research in the Public Interest(GYHY201106008,GYHY201506003)China Meteorological Administration Special Fund for the Development of Numerical Weather Prediction(GRAPES)Research Innovation Program for College Graduates of Jiangsu Province(CXZZ13_0497)
文摘This paper further explores the estimating and expressing of dynamic balance constraints using statistical methods in GRAPES-3DVAR(Version GM). Unlike the single-level scheme which only considers the coupling between mass and wind at one level, the multi-level scheme considers the coupling between their vertical profiles and calculates the balanced mass field at each layer using the rotational wind at all model levels. A reformed ridge regression method is used in the new scheme to avoid the multicollinearity problem and reduce the noises caused by unbalanced mesoscale disturbances. The results of numerical experiments show that the new scheme can get more reasonable vertical mass field, reduce the magnitude of the adjustment by the initialization, and improve the potential temperature analysis performance. Furthermore, the results of forecast verification in January(winter) and July(summer) both confirm that the new scheme can significantly improve the temperature forecast accuracy and bring slight positive effects to the pressure and wind forecast.
基金This project is supported by National Natural Science Foundation of China (No.50005025) Open Foundation of State Key Laboratory of Vibration, Strike and Noise, China (No.VSN-2002-01).
文摘The basic structure of epicyclical gear transmission with inner teeth ofsingle-ring, double-ring, three-ring and four-ring reducer are analyzed. The force analysis model ofring reducer is built. Following this, it is concluded that the present ring reducer~ have theproblem that the inertia force or the inertia moment is lopsided. On the base of analysis andcalculation the balanced ring reducer which can realize the balance of inertia force and inertiamoment is brought forward, and so is its concrete realizing step. The specimen of the balanced ringreducer is designed and manufactured; the experiment is carried out on the gear transmission testbench. Compared with other ring reducer of the same power, the balanced ring reducer has manyadvantages, such as low vibration noise, low cost and less production difficulty and less heat. Itis the substitute of other ring reducer of the same kind. Therefore, it has important theoreticsignificance and highly practical engineering value.
基金supported by the Special Fund for Agro-scientific Research in the Public Interest of China(201203030)the Science and Technology Support Program of Jiangsu,China(BE2013334)the Agricultural Science&Technology Innovation Foundation of Jiangsu Province,China(CX(14)5085)
文摘Phosphorus(P) is an important macronutrient for plant but can also cause potential environmental risk. In this paper, we studied the long-term fertilizer experiment(started 1980) to assess the soil P dynamic, balance, critical P value and the crop yield response in Taihu Lake region, China. To avoid the effect of nitrogen(N) and potassium(K), only the following treatments were chosen for subsequent discussion, including: C0(control treatment without any fertilizer or organic manure), CNK treatment(mineral N and K only), CNPK(balanced fertilization with mineral N, P and K), MNK(integrated organic manure and mineral N and K), and MNPK(organic manure plus balanced fertilization). The results revealed that the response of wheat yield was more sensitive than rice, and no significant differences of crop yield had been detected among MNK, CNPK and MNPK until 2013. Dynamic and balance of soil total P(TP) and Olsen-P showed soil TP pool was enlarged significantly over consistent fertilization. However, the diminishing marginal utility of soil Olsen-P was also found, indicating that high-level P application in the present condition could not increase soil Olsen-P contents anymore. Linear-linear and Mitscherlich models were used to estimate the critical value of Olsen-P for crops. The average critical P value for rice and wheat was 3.40 and 4.08 mg kg^(–1), respectively. The smaller critical P value than in uplands indicated a stronger ability of P supply for crops in this paddy soil. We concluded that no more mineral P should be applied in rice-wheat system in Taihu Lake region if soil Olsen-P is higher than the critical P value. The agricultural technique and management referring to activate the plant-available P pool are also considerable, such as integrated use of low-P organic manure with mineral N and K.
文摘The dynamic balance quality of a rotating object is an important factor to maintain the stability and accuracy for motion. The azimuth of the principal axis of inertia is a major sign of dynamic balance. A usual method is measuring moment of inertia matrix relative to some base coordinates on a rotary inertia machine so as to calculate the azimuth of principal axis of inertia, By using the measured unbalance results on the two trimmed planes on a vertical hard bearing double-plane dynamic balancing machine, the dimension and direction of couple unbalance can be found. An azimuth angle formula for the principal axis of inertia is derived and is solved by using unbalance quantities. The experiments indicate that method based on dynamic balancing measurement is proved rational and effective and has a fine precision.
基金Supported by the Key Projects of the National Natural Science Foundation of China (50834002)
文摘Flow field in multilayer gob area, which formed in small hiden-depth, multi-coal layer groups, close distance, hard coal layer, and hard roof, possesses characteristics such as complex, changeable and unstable. Dynamic balance theory of local flow field in multilayer gob area was built based on the realistic requirement that the serious threat on current mining coal layer by large-scale spontaneous combustion fire on close spontaneous combustion coal layer group of Datong Coal mining area at the 'di-hard' conditions was caused by small coal pit mining. The kernel was in dynamic balance between flow field pressures of working face and local flow field in multilayer gob area was kept by transformation. Corresponding technology and set of devices were developed.
基金This study was partially supported by the Portuguese Foundation for Science and Technology,I.P.under Grant number UIDP/04748/2020.
文摘At age 5,children with trisomy 21 have roughly 2 years of delayed motor development.We aimed to verify if children with trisomy 21(AD)(N=6,7.67±1.51 years)had a similar performance to children with a typical development(TD)(N=37,5.19±0.40 years old),in a playful motor action(to spin on herself until she cannot get more).On average,ADs gave less laps,for less time,spending more time per rotation,but without significant difference.Of the AD,one-third fell and rose to continue to spin;one-third stopped and resumed spinning(with intervals of 2.05±0.86s).Three ADs performed the action counterclockwise and the other three in clockwise direction.The results support the hypothesis that AD can perform the activity of spinning,with DT(significantly)younger,allowing to AD momentary pauses and conditions for their physical security.
基金The National Natural Science Foundation of China(No.69973007).
文摘To solve the load balancing problem in a triplet-based hierarchical interconnection network(THIN) system, a dynamic load balancing (DLB)algorithm--THINDLBA, which adopts multicast tree (MT)technology to improve the efficiency of interchanging load information, is presented. To support the algorithm, a complete set of DLB messages and a schema of maintaining DLB information in each processing node are designed. The load migration request messages from the heavily loaded node (HLN)are spread along an MT whose root is the HLN. And the lightly loaded nodes(LLNs) covered by the MT are the candidate destinations of load migration; the load information interchanged between the LLNs and the HLN can be transmitted along the MT. So the HLN can migrate excess loads out as many as possible during a one time execution of the THINDLBA, and its load state can be improved as quickly as possible. To avoid wrongly transmitted or redundant DLB messages due to MT overlapping, the MT construction is restricted in the design of the THINDLBA. Through experiments, the effectiveness of four DLB algorithms are compared, and the results show that the THINDLBA can effectively decrease the time costs of THIN systems in dealing with large scale computeintensive tasks more than others.
基金This work was supported in part by the National Natural Science Foundation of China under Grant 62171113 and 61941113in part by the Fundamental Research Funds for the Central Universities under Grant N2116003 and N2116011.
文摘Mobile Edge Computing(MEC)-based computation offloading is a promising application paradigm for serving large numbers of users with various delay and energy requirements.In this paper,we propose a flexible MECbased requirement-adaptive partial offloading model to accommodate each user's specific preference regarding delay and energy consumption.To address the dimensional differences between time and energy,we introduce two normalized parameters and then derive the computational overhead of processing tasks.Different from existing works,this paper considers practical variations in the user request patterns,and exploits a flexible partial offloading mode to minimize computation overheads subject to tolerable delay,task workload and power constraints.Since the resulting problem is non-convex,we decouple it into two convex subproblems and present an iterative algorithm to obtain a feasible offloading solution.Numerical experiments show that our proposed scheme achieves a significant improvement in computation overheads compared with existing schemes.
基金supported by National Hi-tech Research and Development Program of China (863 Program, Grant No. 2008 AA04Z114)
文摘Measurement error of unbalance's vibration response plays a crucial role in calibration and on-line updating of influence coefficient(IC). Focusing on the two problems that the moment estimator of data used in calibration process cannot fulfill the accuracy requirement under small sample and the disturbance of measurement error cannot be effectively suppressed in updating process, an IC calibration and on-line updating method based on hierarchical Bayesian method for automatic dynamic balancing machine was proposed. During calibration process, for the repeatedly-measured data obtained from experiments with different trial weights, according to the fact that measurement error of each sensor had the same statistical characteristics, the joint posterior distribution model for the true values of the vibration response under all trial weights and measurement error was established. During the updating process, information obtained from calibration was regarded as prior information, which was utilized to update the posterior distribution of IC combined with the real-time reference information to implement online updating. Moreover, Gibbs sampling method of Markov Chain Monte Carlo(MCMC) was adopted to obtain the maximum posterior estimation of parameters to be estimated. On the independent developed dynamic balancing testbed, prediction was carried out for multiple groups of data through the proposed method and the traditional method respectively, the result indicated that estimator of influence coefficient obtained through the proposed method had higher accuracy; the proposed updating method more effectively guaranteed the measurement accuracy during the whole producing process, and meantime more reasonably compromised between the sensitivity of IC change and suppression of randomness of vibration response.
基金supported by the National Natural Science Foundation of China(No.61163058No.61201250 and No.61363006)Guangxi Key Laboratory of Trusted Software(No.KX201306)
文摘In order to balancing based on data achieve dynamic load flow level, in this paper, we apply SDN technology to the cloud data center, and propose a dynamic load balancing method of cloud center based on SDN. The approach of using the SDN technology in the current task scheduling flexibility, accomplish real-time monitoring of the service node flow and load condition by the OpenFlow protocol. When the load of system is imbalanced, the controller can allocate globally network resources. What's more, by using dynamic correction, the load of the system is not obvious tilt in the long run. The results of simulation show that this approach can realize and ensure that the load will not tilt over a long period of time, and improve the system throughput.
基金Project supported by the National Natural Science Foundation of China (No.10176011).
文摘A new type of vibration structure (i.e. supporting system, called swing frame cus- tomarily) of vertical dynamic balancing machine has been designed, which is based on an analysis for the swing frame of a traditional double-plane vertical dynamic balancing machine. The static unbalance and couple unbalance can be e?ectively separated by using the new dynamic balancing machine with the new swing frame. By building the dynamics model, the advantages of the new structure are discussed in detail. The modal and harmonic response are analyzed by using the ANSYS7.0. By comparing the ?nite element modal analysis with the experimental modal analy- sis, the natural frequencies and vibration modes are found. There are many spring boards in the new swing frame. Their sti?nesses are di?erent and assorted with each other. Furthermore, there are three sensors on the measuring points. Therefore, the new dynamic balancing machine can measure static unbalance and coupling unbalance directly, and the interaction between them is faint. The result shows that the new vertical dynamic balancing machine is suitable for inertial measurement of ?ying objects, and can overcome the shortcomings of traditional double-plane vertical dynamic balancing machines, which the e?ect of plane-separation is inferior. The vertical dynamic balancing machine with the new vibration structure can ?nd wide application in the future. The modelling and analysis of the new vibration structure will provide theoretical basis and practical experience for designing new-type vertical dynamic balancing machines.
基金the National Natural Science Foundation of China(69973007)
文摘To decrease the cost of exchanging load information among processors, a dynamic load-balancing (DLB) algorithm which adopts multieast tree technology is proposed. The muhieast tree construction rules are also proposed to avoid wrongly transferred or redundant DLB messages due to the overlapping of multicast trees. The proposed DLB algorithm is distributed controlled, sender initiated and can help heavily loaded processors with complete distribution of redundant loads with minimum number of executions. Experiments were executed to compare the effects of the proposed DLB algorithm and other three ones, the results prove the effectivity and practicability of the proposed algorithm in dealing with great scale compute-intensive tasks.
文摘Unbalanced vibration in dual-rotor rotating machinery was studied with numerical simulations and experiments. A new method is proposed to separate vibration signals of inner and outer rotors for a system with very little difference in rotating speeds. Magnitudes and phase values of unbalance defects can be obtained directly by sampling the vibration signal synchronized with reference signal. The balancing process is completed by the reciprocity influence coefficients of inner and outer rotors method. Results showed the advantage of such method for a dual-rotor system as compared with conventional balancing.
文摘The rapid growth of interconnected high performance workstations has produced a new computing paradigm called clustered of workstations computing. In these systems load balance problem is a serious impediment to achieve good performance. The main concern of this paper is the implementation of dynamic load balancing algorithm, asynchronous Round Robin (ARR), for balancing workload of parallel tree computation depth-first-search algorithm on Cluster of Heterogeneous Workstations (COW) Many algorithms in artificial intelligence and other areas of computer science are based on depth first search in implicitty defined trees. For these algorithms a load-balancing scheme is required, which is able to evenly distribute parts of an irregularly shaped tree over the workstations with minimal interprocessor communication and without prior knowledge of the tree’s shape. For the (ARR) algorithm only minimal interprocessor communication is needed when necessary and it runs under the MPI (Message passing interface) that allows parallel execution on heterogeneous SUN cluster of workstation platform. The program code is written in C language and executed under UNIX operating system (Solaris version).
文摘This paper proposes a dynamic load balancing with learning model for a Sudoku problem solving system that has multiple workers and multiple solvers.The objective is to minimise the total processing time of problem solving.Our load balancing with learning model distributes each Sudoku problem to an appropriate pair of worker and solver when it is received by the system.The information of the estimated solution time for a specific number of given input values,the estimated finishing time of each worker,and the idle status of each worker is used to determine the worker-solver pairs.In addition,the proposed system can estimate the waiting period for each problem.Test results show that the system has shorter processing time than conventional alternatives.
文摘Influence coefficient method and the modal balancing method are often used in the dynamic balancing in the past days. These methods sometimes exist a lot of big measurement errors. So, in order to make these errors much smaller, and to use the vibration information of the rotor more sufficiently, at last, we put forward the full vector dynamic balancing algorithm. Though the theoretical analysis, and the experiment tests, we can compare with the new method and the old method , study the relationship between the dynamic balancing and the rotation equipment, and the direction of the development. The full vector dynamic balancing algorithm theory can be inferred from the Jeffcott rotor. To compare with the methods which are mentioned before, we can find that the full vector dynamic balancing algorithm is much better than the influence coefficient method and the modal balancing method. We can use the MATLAB program to prove that the full vector dynamic balancing algorithm is much better. So the conclusion is completely right.
基金funded by Shandong Province Youth Innovative Talent Induction Program(grant number 2019-183)the National Key R&D Program of China(2018YFC2000600).
文摘Background:Balance impairment is one of the strongest risk factors for falls.Proprioception,cutaneous sensitivity,and muscle strength are 3 important contributors to balance control in older adults.The relationship that dynamic and static balance control has to proprioception,cutaneous sensitivity,and muscle strength is still unclear.This study was performed to investigate the relationship these contributors have to dynamic and static balance control.Methods:A total of 164 older adults(female=89,left dominant=15,age:73.5±7.8 years,height:161.6±7.1 cm,weight:63.7±8.9 kg,mean±SD)participated in this study.It tested the proprioception of their knee flexion/extension and ankle dorsi/plantarflexion,along with cutaneous sensitivity at the great toe,first and fifth metatarsals,arch,and heel,and the muscle strength of their ankle dorsi/plantarflexion and hip abduction.The Berg Balance Scale(BBS)and the root mean square(RMS)of the center of pressure(CoP)were collected as indications of dynamic and static balance control.A partial correlation was used to determine the relationship between the measured outcomes variables(BBS and CoPRMS)and the proprioception,cutaneous sensitivity,and muscle strength variables.Results:Proprioception of ankle plantarflexion(r=-0.306,p=0.002)and dorsiflexion(r=-0.217,p=0.030),and muscle strength of ankle plantarflexion(r=0.275,p=0.004),dorsiflexion(r=0.369,p<0.001),and hip abduction(r=0.342,p<0.001)were weakly to moderately correlated with BBS.Proprioception of ankle dorsiflexion(r=0.218,p=0.020)and cutaneous sensitivity at the great toe(r=0.231,p=0.041)and arch(r=0.285,p=0.002)were weakly correlated with CoP-RMS in the anteroposterior direction.Proprioception of ankle dorsiflexion(r=0.220,p=0.035),knee flexion(r=0.308,p=0.001)and extension(r=0.193,p=0.040),and cutaneous sensitivity at the arch(r=0.206,p=0.028)were weakly to moderately correlated with CoP-RMS in the mediolateral direction.Conclusion:There is a weak-to-moderate relationship between proprioception and dynamic and static balance control,a weak relationship between cutaneous sensitivity and static balance control,and a weak-to-moderate relationship between muscle strength and dynamic balance control.
文摘Recovery from stroke needs different time and speed in every case depending on the brain capacity of neural plasticity. Based on neurophysiological researches high repetition of practice is required to induce neuroplastic changes and functional recovery of motor deficits. However, data from earlier studies shows that stroke patients generally perform a very limited number of movement repetitions in traditional therapy sessions. Virtual Reality therapy was found to be beneficial in improving trunk, hand, upper and lower extremity functions. However, reviews found no definitive conclusions regarding balance. The present study focuses on evaluating the efficacy of Nintendo WiiTM on balance and gait functions of stroke patients. Twenty one hemiparetic stroke patients were randomly assigned to either control or therapy groups. Effectiveness was evaluated by Fugl-Meyer balance subtest, Functional Ambulation Categories (FAC), Romberg (R), sharpened Romberg (SR), one-legged stance (OLS), six-meter walking test (6MWT) and timed up and go test (TUG). The analysis revealed a significant effect of training with Nintendo Wii M for FAC z = 0.0267, FMBS z = 0.0046, OLST2 z = 0.0068 and OLS1 z = 0.0067 (affected side). The control group demonstrated improvement in R (z = 0.0474) and SR (z = 0.0411). In both groups improvement was detected in functional mobility and 6MWT (control group z = 0.0069, Wii groupz = 0.0123). No significant differences were found between groups. Findings of the current study support that balance treatment with Nintendo WiiTM is similarly effective method to improve static balance and functional mobility when compared with conventional therapy.
文摘Proper balance is essential for athletes during competition and training as sport places different balance requirements on the human body. The purpose of the study was to analyze balance performance among female athletes using COP (center of pressure) sway parameters. Twenty one NCAA (National Collegiate Athletic Association) division I female athletes (soccer, volleyball and dance) completed the study. Static balance was assessed using UST (unilateral stance test) and dynamic balance was assessed using MCT (motor control test) on the NeuroCom Equitest. Sway velocities, root mean square sway and reaction time latencies were used to quantify balance. A one-way between subjects ANOVA (analysis of variance) was performed to analyze these balance parameters. Significant (p 〈 0.05) differences between groups were found and post hoc comparisons revealed that the volleyball and dance groups had better static balance compared to soccer players, while both soccer and volleyball groups had better dynamic balance compared to the dance group. The results from the study indicate two points: first, differences in balance performance among female athletes in different sporting discipline; second, there is no relationship between static and dynamic balance. This indicates that it may be more beneficial to assess and train for static and dynamic balance individually.
基金support from the Royal Society Newton Advanced Fellowship(NA170184)support from the National Natural Science Foundation of China(52003290,52173052,52203021)the Natural Science Foundation of Jiangsu Province(BK20220296).
文摘Aerogels are of great interest in diverse fields including thermal insulation,environmental protection,liquid separation,electromagnetic shielding,etc.However,the development of renewable and recyclable aerogels,especially synthetic pol-ymer-based ones,remains an enormous challenge,which seriously hinders the practical application of aerogels.Herein,utilizing Kevlar nanofibers(KNFs)as representative synthetic polymer building blocks,a destabilizing dynamic balance(DDB)strategy is proposed to fabricate recyclable aerogels with high reprocessing consistency.More specifically,aprotic esters(e.g.,di-tert-butyl decarbonate,DiBoc)and alkalis(e.g.,potassium tert-butoxide,t-BuOK)are introduced to trigger the destabilizing dynamic balance between deprotonation–protonation of KNFs,resulting in a reversible sol–gel transition.Meanwhile,the duration of sol–gel transition(i.e.,gelation)time,adjustable from 10^(–2)to 10^(3)min,is compatible with versatile processing methods,such as static mould casting,dynamic wet spinning,dynamic blade coating and dynamic 3D printing.These unique advantages enable the fabrication of various KNF aerogel products(i.e.,continuous fibers,continuous films,large-sized monoliths and 3D-printed articles)with low density(33–165 mg/cm3),high compressive modulus(up to 52 MPa),high specific surface area(360–404 m^(2)/g)and low thermal conductivity(0.027–0.050 W/m·K).Notably,these properties are comparable or superior to that of previously reported KNF aerogels and far superior to that of recyclable aerogels.Compared with direct fabrication from raw materials,the DDB strategy reduces the cost by 50.5%and 82.5%when products are made from recycled aerogels and wet gels,respectively.Such cost reduction further increases with the number of recycling cycles,which is calculated as$275 per kilogram KNF aerogel with 5 cycles.This work develops extraordinary KNF aerogels those can be recycled and reused,as well as provides a strategy that can be applied to design more recyclable aerogels.