基于位置的身份验证

使用地理位置作为身份识别的唯一特征,提出一种新的基于位置的身份验证的方案。新方案改进了以往方案在测量时间响应时要求过于精确这一弊端,针对BSM模型的存储能力有限、对于同时接收到的信息可以计算但不能存储这一特点进行设计,所以它对时间响应并无特殊要求。新方案使基于位置的身份验证的方法更加多元化,防攻击的手段更加丰富,并在此基础上设计了一种基于位置的密钥交换协议。     

Transmission in mobile cloudlet systems with intermittent connectivity in emergency areas

The recent development of Mobile Cloud Computing has helped in solving numerous real-life problems. The rate of growth of mobile devices has been increasing at a very high pace. Mobile devices have made substantial contributions in managing emergency situations. Owing to the mobility of mobile devices, cloudlets, and their intermittent connectivity, it may become very difficult to handle emergency situations. To address this problem, a transmission model is proposed for mobile cloudlet systems, where a mobile device is used to designate a cloudlet by using the Borda scores Method and the mobile device can offload a part of its application to this cloudlet. The simulation results demonstrated that the proposed work makes a significant comtribution toward alleviating the problems associated with emergency situations.     

单纯形最优化法介绍

本文简要介绍了在分析化学领域中得到广泛应用的单纯形最优化法,主要是基本单纯形法和改进型单纯形法。     

An ASM/ADM model interface for dynamic plant-wide simulation

Mathematical modelling has proven to be very useful in process design, operation and optimisation. A recent trend in WWTP modelling is to include the different subunits in so-called plant-wide models rather than focusing on parts of the entire process. One example of a typical plant-wide model is the coupling of an upstream activated sludge plant (including primary settler, and secondary clarifier) to an anaerobic digester for sludge digestion. One of the key challenges when coupling these processes has been the definition of an interface between the well accepted activated sludge model (ASM1) and anaerobic digestion model (ADM1). Current characterisation and interface models have key limitations, the most critical of which is the over-use of X_c (or lumped complex) variable as a main input to the ADM1. Over-use of X_c does not allow for variation of degradability, carbon oxidation state or nitrogen content. In addition, achieving a target influent pH through the proper definition of the ionic system can be difficult. In this paper, we define an interface and characterisation model that maps degradable components directly to carbohydrates, proteins and lipids (and their soluble analogues), as well as organic acids, rather than using X_c. While this interface has been designed for use with the Benchmark Simulation Model No. 2 (BSM2), it is widely applicable to ADM1 input characterisation in general. We have demonstrated the model both hypothetically (BSM2), and practically on a full-scale anaerobic digester treating sewage sludge.     

主机型异常检测的隐半马尔可夫模型方法

提出基于HSMM模型的主机型入侵检测系统框架。以BSM审计数据作为数据源,提取正常主机行为的特权流系统调用序列,利用HSMM模型对正常主机行为进行建模,然后将当前主机行为与之比较,判定当前主机行为是否异常。选取特权流变化事件作为研究对象以缩短建模时间,同时滤去了过多的无用信息,一定程度上提高了检测效率。实验结果表明,提出的HSMM方法比HMM优越,同时该方法建模的系统不仅节省训练时间,而且在提高检测率的同时可以降低误报率。     

Continuity-based model interfacing for plant-wide simulation: a general approach

In plant-wide simulation studies of wastewater treatment facilities, often existing models from different origin need to be coupled. However, as these submodels are likely to contain different state variables, their coupling is not straightforward. The continuity-based interfacing method (CBIM) provides a general framework to construct model interfaces for models of wastewater systems, taking into account conservation principles. In this contribution, the CBIM approach is applied to study the effect of sludge digestion reject water treatment with a SHARON-Anammox process on a plant-wide scale. Separate models were available for the SHARON process and for the Anammox process. The Benchmark simulation model no. 2 (BSM2) is used to simulate the behaviour of the complete WWTP including sludge digestion. The CBIM approach is followed to develop three different model interfaces. At the same time, the generally applicable CBIM approach was further refined and particular issues when coupling models in which pH is considered as a state variable, are pointed out.     

State estimation for large-scale wastewater treatment plants

Many relevant process states in wastewater treatment are not measurable, or their measurements are subject to considerable uncertainty. This poses a serious problem for process monitoring and control. Model-based state estimation can provide estimates of the unknown states and increase the reliability of measurements. In this paper, an integrated approach is presented for the optimization-based sensor network design and the estimation problem. Using the ASM1 model in the reference scenario BSM1, a cost-optimal sensor network is designed and the prominent estimators EKF and MHE are evaluated. Very good estimation results for the system comprising 78 states are found requiring sensor networks of only moderate complexity.     

Applying variable dissolved oxygen set point in a two level hierarchical control structure to a wastewater treatment process

This paper presents a two-level hierarchical control structure for biological wastewater treatment plants, with the goal of improving effluent quality and reducing operational costs. The Benchmark Simulation Model No. 1 is used as working scenario. The hierarchical structure allows to adjust the dissolved oxygen in the fifth tank (S_O,5) according with the working conditions, instead of keeping it in a fixed value. Model Predictive Control (MPC) with inlet flow rate feedforward control (MPC + FF) is proposed for the lower level to control nitrate nitrogen concentration of the second tank and S_O,5. MPC, Affine Function and fuzzy controller are tested for the higher level to adjust the S_O,5 set point of the lower level based on the ammonium and ammonia nitrogen concentration in the fifth tank. Modifying the tuning parameters of the higher level, a tuning region is determined, in which the effluent quality and operational costs are simultaneously improved.     

Dynamic influent pollutant disturbance scenario generation using a phenomenological modelling approach

Activated Sludge Models are widely used for simulation-based evaluation of wastewater treatment plant (WWTP) performance. However, due to the high workload and cost of a measuring campaign on a full-scale WWTP, many simulation studies suffer from lack of sufficiently long influent flow rate and concentration time series representing realistic wastewater influent dynamics. In this paper, a simple phenomenological modelling approach is proposed as an alternative to generate dynamic influent pollutant disturbance scenarios. The presented set of models is constructed following the principles of parsimony (limiting the number of parameters as much as possible), transparency (using parameters with physical meaning where possible) and flexibility (easily extendable to other applications where long dynamic influent time series are needed). The proposed approach is sub-divided in four main model blocks: 1) model block for flow rate generation, 2) model block for pollutants generation (carbon, nitrogen and phosphorus), 3) model block for temperature generation and 4) model block for transport of water and pollutants. The paper is illustrated with the results obtained during the development of the dynamic influent of the Benchmark Simulation Model no. 2 (BSM2). The series of simulations show that it is possible to generate a dry weather influent describing diurnal flow rate dynamics (low rate at night, high rate during day time), weekend effects (with different flow rate during weekends, compared to weekdays), holiday effects (where the wastewater production is assumed to be different for a number of weeks) and seasonal effects (with variations in the infiltration and thus also the flow rate to the WWTP). In addition, the dry weather model can be extended with a rain and storm weather generator, where the proposed phenomenological model can also mimic the “first flush” effect from the sewer network and the influent dilution phenomena that are typically observed at full-scale WWTPs following a rain event. Finally, the extension of the sewer system can be incorporated in the influent dynamics as well: the larger the simulated sewer network, the smoother the simulated diurnal flow rate and concentration variations. In the discussion, it is pointed out how the proposed phenomenological models can be expanded to other applications, for example to represent heavy metal or organic micro-pollutant loads entering the treatment plant.     

盾构衬砌单环破坏历程的增量法解析解

作为盾构整环管片破坏研究的一部分,采用增量法对单环在荷载作用下逐渐破坏的历程进行了解析解推导,提出了可考虑管片接头非线性转动的单环受荷历程的相对刚度比法和弯矩搜索法两种解析方法,并对已经通过盾构整环原型破坏试验数据详细校核的数值模型进行适当修正,构造出了对解析解进行检验的数值模型,通过对解析解和数值解的比较表明,相对刚度比法、弯矩搜索法两种增量解析方法可以较为准确的刻画出单环衬砌的受荷破坏历程,是可行的。