Cooperative Multi-Agent Reinforcement Learning with Constraint-Reduced DCOP

Cooperative multi-agent reinforcement learning (MARL) is an important topic in the field of artificial intelligence,in which distributed constraint optimization (DCOP) algorithms have been widely used to coordinate the actions of multiple agents.However,dense communication among agents affects the practicability of DCOP algorithms.In this paper,we propose a novel DCOP algorithm dealing with the previous DCOP algorithms' communication problem by reducing constraints.The contributions of this paper are primarily threefold:① It is proved that removing constraints can effectively reduce the communication burden of DCOP algorithms.② An criterion is provided to identify insignificant constraints whose elimination doesn't have a great impact on the performance of the whole system.③ A constraint-reduced DCOP algorithm is proposed by adopting a variant of spectral clustering algorithm to detect and eliminate the insignificant constraints.Our algorithm reduces the communication burdern of the benchmark DCOP algorithm while keeping its overall performance unaffected.The performance of constraint-reduced DCOP algorithm is evaluated on four configurations of cooperative sensor networks.The effectiveness of communication reduction is also verified by comparisons between the constraint-reduced DCOP and the benchmark DCOP.     

Influence of Structural Parameters of Turbocharger Floating Bearing on Its Dynamic Characteristic Coefficients

The structure parameters in an actual industrial production have a great influence on the coefficient of supercharger floating bearing dynamic characteristics,but there has been little systematic study so far. In this paper, the influence of structural parameters of the turbocharger floating bearing on its dynamic characteristic coefficientsis systematically investigated based on the theories of hydrodynamic lubrication and tribology. The influence of clearance ratio on eccentricity and the influence of internal to external radius ratios, and Sommerfeld number were analyzed.A new formula of responding characteristics of the oil film force caused by the displacement or velocity disturbance was deduced near an equilibrium in the steady state. Applying the newly developed formula, the dynamic characteristic was studied for floating bearings. Regularity for change of oil film stiffness and damping was analyzed with the structural parameters of floating bearing such as radius ratios and eccentricity.It has been found that the clearance ratio increases with eccentricity when the radius ratio is unchanged.The eccentricity decreases with the internal to external radius ratio of floating rings when the clearance ratio is constant.The absolute value of total principal stiffness and total main damping decrease with the clearance ratio and radius ratio of floating rings when the total cross damping is stable. The results and findings in this paper can contribute to nonlinear dynamics designs of turbocharger rotor-bearing systems.     

沧州市2006~2016年春季大到暴雨特征分析

根据沧州市92个雨量监测站2006~2016年间的春季大到暴雨资料,研究了11年来沧州市春季大到暴雨的特征指标、时间变化规律以及空间变化趋势.研究发现:沧州市11年间春季大到暴雨强度(站点数)的时间变化呈抛物线趋势,与沧州市年降水量变化趋势非常接近;沧州市春季大到暴雨的空间分布情况为各县市均有发生,但分布不均匀,子牙新河沿岸出现高值区,以子牙新河为界,向两侧递减.     

政府吸纳网络民意的现实困境和策略选择

网络民意的发展及其政治地位的确立,使其成为各级政府行政决策合法化的重要考量因素,整合吸纳网络民意成为政府管理职责有效履行的必然选择.然而,政府在吸纳网络民意的过程中,受网络民意表达的非理性、分散性、复杂性、急迫性等特点,以及政府决策理性化、集中性、科学化、滞后性等特点的影响,面临着自由与秩序的冲突、权力与利益的博弈、理性与非理性的抗衡等现实困境,亟须政府优化政民互动、民意甄别分析、民意吸纳反馈等机制,依法加强网络空间治理力度,主动提高官员网络媒介素养,以保障对网络民意吸纳的效度.     

无线通信网络容量优化研究

由于通信技术的飞速发展与通信用户的急剧增长,通信用户需求业务的多媒体化,促使通信网络不断向用户业务多媒体化发展,因此通信网络的架构在演进过程中除了应考虑用户通信业务的承载能力,同时还应考虑网络容量的问题.那么如何在有限的无线资源下,来提升网络的容量、提高通信资源的有效利用率,给无线通信网络容量优化提出了新的挑战.     

音频大地电磁测深在某隧道工程中的应用

音频大地电磁(AMT)在隧道的工程地质勘察是一种非常有效的方法,它具有不受高阻屏蔽、轻便、探测深度相对较大等优点,在宏观上可以查明隧道地层岩性分界、地质构造及其赋水性。以某隧道音频大地电磁勘察为例,分别对AMT的采集手段、工频干扰去噪、静态校正、反演方法等关键技术问题进行分析,并结合实际资料对该工作区的地层分布、断层及其破碎带的赋水情况等进行分析和解释,在其应用中取得了理想的效果。     

唑类化合物双氢键催化转酰胺反应的机制研究

通过密度泛函M062X方法在6-31+G(d)基组水平上考察乙酰胺与甲胺在唑类化合物咪唑、吡唑和苯并三唑双氢键催化作用下的转酰胺反应机制。在该机制中,催化剂通过与底物乙酰胺的羰基氧以及氨基上的一个氢形成双氢键来活化其酰胺键,从而有利于亲核试剂甲胺对乙酰胺酰胺键的亲核进攻。计算结果显示,咪唑和吡唑催化的转酰胺反应焓变能垒分别是123.9 kJ·mol-1和92.3 kJ·mol-1,而苯并三唑做催化剂时焓变能垒降低为88.3 kJ·mol-1,其催化效果优于咪唑和吡唑。当运用溶质全电子密度溶剂化模型SMD (solvation model density)来考察甲苯和水作为溶剂对苯并三唑催化的转酰胺反应产生的溶剂效应时,发现溶剂的加入使反应焓变能垒明显升高,说明溶剂的加入并不利于反应的进行     

酸碱影响下砂岩流变参数识别方法及敏感度

根据长期暴露在自然环境中的砂质岩体易遭受水及可溶离子化学侵蚀作用的事实,通过对相同浓度不同pH值CaCl₂试剂浸泡处理过的砂岩试件进行三轴剪切试验,根据试验结果选取符合试验规律的二阶简化广义Kelvin流变模型,按照定泊松比假设将其变形为三项应力状态。基于搜索模式的最小二乘方法（LSMPS）获取模型参数最优解,以均方根误差评价模型对各参数变化的敏感性程度。采用延迟时间评价砂岩在不同化学环境中达到稳定蠕变过程所需时间。通过搜索模式识别的模型参数能够使模型计算值与加载试验获得的实测值比较接近,表明该模型及其参数识别方法在确定受化学因素干扰下的砂岩流变特征比较适用。     

Broadband terahertz spectroscopy of amino acids

Broadband spectra of 20 L-amino acids were obtained at room temperature by terahertz time-domain and infrared spectroscopy. The intensity of terahertz absorption peaks varied with the concentrations of amino acids, and the optimum proportion for each amino acid was obtained. An absorption spectral database of 20 L-amino acids was established from 0 to 6 THz. The associations between terahertz absorption peaks and molecular structures of amino acids were analyzed. The terahertz spectra for L-alanine were compared with the calculated results based on density functional theory using two basis sets that were reliably consistent.     

Characterization and methanol adsorption of walnut-shell activated carbon prepared by KOH activation

Walnut-shellactivated carbons(WSACs)were prepared by the KOH chemicalactivation.The effects of carbonization temperature,activation temperature,and ratio of KOH to chars on the pore development of WSACs were investigated.Fourier transform infrared spectroscopy(FTIR),X-ray powder diffraction(XRD),and scanning electron microscopy(SEM)were employed to characterize the microstructure and morphology of WSACs.Methanoladsorption performance onto the optimalWSAC and the coal-based AC were also investigated.The results show that the optimalpreparation conditions are a carbonization temperature of 700 ℃,an activation temperature of 700 ℃,and a mass ratio of 3.The BET surface area,the micropore volume,and the micropore volume percentage of the optimalWASC are 1636 m~2/g,0.641 cm~3/g and 81.97%,respectively.There are a lot of micropores and a certain amount of meso-and macropores.The characteristics of the amorphous state are identified.The results show that the optimalWSAC is favorable for methanoladsorption.The equilibrium adsorption capacity of the optimalWSAC is 248.02mg/g.It is shown that the equilibrium adsorption capacity of the optimalWSAC is almost equivalent to that of the common activated carbon.Therefore the optimalWSAC could be a potentialadsorbent for the solar energy adsorption refrigeration cycle.