A Survey of Model Predictive Control Methods for Traffic Signal Control

Enhancing traffic efficiency and alleviating(even circumventing) traffic congestion with advanced traffic signal control(TSC) strategies are always the main issues to be addressed in urban transportation systems. Since model predictive control(MPC) has a lot of advantages in modeling complex dynamic systems, it has been widely studied in traffic signal control over the past 20 years. There is a need for an in-depth understanding of MPC-based TSC methods for traffic networks. Therefore, this paper presents the motivation of using MPC for TSC and how MPC-based TSC approaches are implemented to manage and control the dynamics of traffic flows both in urban road networks and freeway networks. Meanwhile, typical performance evaluation metrics, solution methods, examples of simulations,and applications related to MPC-based TSC approaches are reported. More importantly, this paper summarizes the recent developments and the research trends in coordination and control of traffic networks with MPC-based TSC approaches. Remaining challenges and open issues are discussed towards the end of this paper to discover potential future research directions.

Enzyme activities and gene expression of starch metabolism provide insights into grape berry development

Grapes are categorized as a non-climacteric type of fruit which its ripening is not associated to important rises in respiration and ethylene synthesis.The starch metabolism shares a certain role in the carbohydrate metabolic pathways during grape berry development,and is regarded as an important transient pool in the pathway of sugar accumulation.However,the comprehensive role of starch and its contribution to the quality and flavor of grape berry have not been explored thoroughly.In this study,the expression levels of genes enzyme activities and carbohydrate concentrations related to starch metabolism,were analyzed to understand the molecular mechanism of starch accumulation during grape berry development.The results indicated that starch granules in grape berry were located at the chloroplast in the sub-epidermal tissues,acting as the temporary reserves of photosynthetic products to meet the needs for berry development,and relatively high starch contents could be detected at véraison stage.Moreover,both ADP-glucose pyrophosphorylase(EC 2.7.7.27)and sucrose phosphate synthase(EC 2.3.1.14)involved in starch synthesis displayed elevated gene expression and enzymes activities in the sub-epidermal tissue,whileα-andβ-amylases involved in its degradation were highly transcribed and active in the central flesh,explaining the absence of starch in this last tissue.Change in the gene expression and activities of ADP-glucose pyrophosphorylase,β-amylase and sucrose phosphate synthase revealed that they were regulated by the circadian rhythms in the fruitlets compared with those in the leaves.Both the morphological,enzymological and transcriptional data in this study provide advanced understandings on the function of starch during berry development and ripening that are so important for berry quality.This study will further facilitate our understanding of the sugar metabolism in grape berry as well as in other plant species.

A Numerical Study of the TipWake of aWind Turbine Impeller Using Extended Proper Orthogonal Decomposition

The behavior of the tip wake of a wind turbine is one of the hot issues in the wind power field.This problem can partially be tackled using Computational Fluid Dynamics(CFD).However,this approach lacks the ability to provide insights into the spatial structure of important high-order flows.Therefore,with the horizontal axis wind turbine as the main focus,in this work,firstly,we conduct CFD simulations of the wind turbine in order to obtain a data-driven basis relating to multiple working conditions for further analysis.Then,these data are studied using an extended Proper Orthogonal Decomposition(POD)algorithm.The quantitative results indicate that the tip vortex in the wake has a complicated spatio-temporal morphological configuration in the higher-order extended POD space.The radial velocity modes obtained are effective and credible,and such reconstructed flow of the tip vortex becomes clearer with the increase of the reconstruction orders.Interestingly,the changes of relatively high-order correlation coefficients are essentially affected by the periodic fusion of tip and central eddies in the wake.

Collision and Deadlock Avoidance in Multi-Robot Systems Based on Glued Nodes

Dear editor,In this letter,we would like to discuss a method to avoid collisions and deadlocks in multi-robot systems based on a new concept of glued nodes.In terms of collision and deadlock avoidance,many methods are based on zone control which has two disadvantages.First,unless all nodes are collision-free,the roadmap must be divided into disjoint zones,which increases the difficulty of applying the methods.Moreover,each zone should be able to accommodate a robot,which leads to imprecision and waste of space.This letter proposes the concept of glued nodes,which can dynamically determine the mutual influence between nodes based on the real-time sizes and paths of the robots.Based on the glued nodes,this letter proposes a collision and deadlock avoidance algorithm,which can be applied to multi-robot systems with variable-sized robots and roadmaps with any structure.The experimental results indicate that the method proposed in this letter is effective and efficient.

Dynamic Spectrum Access Scheme of Variable Service Rate and Optimal Buffer-Based in Cognitive Radio

Dynamic spectrum access (DSA) scheme in Cognitive Radio (CR) can solve the current problem of scarce spectrum resource effectively, in which the unlicensed users (i.e. Second Users, SUs) can access the licensed spectrum in opportunistic ways without interference to the licensed users (i.e. Primary Users, PUs). However, SUs have to vacate the spectrum because of PUs coming, in this case the spectrum switch occurs, and it leads to the increasing of SUs’ delay. In this paper, we proposed a Variable Service Rate (VSR) scheme with the switch buffer as to real-time traffic (such as VoIP, Video), in order to decrease the average switch delay of SUs and improve the other performance. Different from previous studies, the main characteristics of our studying of VSR in this paper as follows: 1) Our study is on the condition of real-time traffic and we establish three-dimension Markov model;2) Using the internal optimization strategy, including switching buffer, optimizing buffer and variable service rate;3) As to the real-time traffic, on the condition of meeting the Quality of Service(QoS) on dropping probability, the average switch delay is decreased as well as improving the other performance. By extensive simulation and numerical analysis, the performance of real-time traffic is improved greatly on the condition of ensuring its dropping probability. The result fully demonstrates the feasibility and effectiveness of the variable service rate scheme.

Flame Burn Injury in Yichang of China:the Trends,Complications,and Risk Factor Analysis

Background A flame burn is an injury of body tissues,including respiratory tract damage,due to exposure to a flame or its dense smoke.Flame burns cause some of the most physically and psychologically devastating forms of trauma.Compared to scald burns,flame burn patients have a higher mortality rate and a higher frequency of multiorgan failure.The purpose of this research was to investigate the trends,complications,and mortality risk factors of flame burns at the Department of Plastic and Burn Surgery(DPBS)of the People’s Hospital of China Three Gorges University(PHCTGU).Methods A retrospective analysis of 48 flame burn patients—accounting for 8.3%of the 576 burn victims admitted for burns at the PHCTGU from February 1,2010,to September 30,2019—was performed after collecting information from the Burns Registry of the said hospital.Results The proportion of patients with flame burns was 8.3%(n=48).The mean total body surface area(TBSA)affected was 27.6%.The mean duration of hospitalization was 32.5 days.The etiologies of the flame burns were as follows:gas explosions(21,43.8%),ethanol(8,16.7%),charcoal fire(7,14.6%),petrol explosions(4,8.3%),wooden houses(4,8.3%),and others,including dust,cigarette lighter,and burning incense,accounting for 8.3%of cases(4).Finally,42(87.5%)patients were treated and discharged,and 6(12.5%)patients died.Complications included scarring in 38(90.5%)patients,severe scar contractures on different parts of the body in 25(60.0%)patients,scar ulcer in 6(14.3%)patients,keloids in 3(7.1%)patients,and scar cancer in 1(2.4%)patient.Multiple complications occurred in the same patient.The only risk factor for mortality that was identified was TBSA(P=0.043).Conclusions Our study revealed that a small population(8.3%)was injured by flame burns,but 6 deaths were recorded.Society must continually enhance safeguard procedures to flames and strengthen education to protect life and avoid severe complications.

Asymmetrical Fault Current Calculation Method and Influencing Factors Analysis of Droop-Controlled Inverters

Since the fault dynamic of droop-controlled inverter is different from synchronous generators (SGs), protection devices may become invalid, and the fault overcurrent may damage power electronic devices and threaten the safety of the microgrid. Therefore, it is imperative to conduct a comprehensive fault analysis of the inverter to guide the design of protection schemes. However, due to the complexity of droop control strategy, existing literatures have simplified asymmetric fault analysis of droop-controlled inverters to varying degrees. Therefore, accurate fault analysis of a droop-controlled inverter is needed. In this paper, by analyzing the control system, an accurate fault model is established. Based on this, a calculation method for instantaneous asymmetrical fault current is proposed. In addition, the current components and current characteristics are analyzed. It was determined that fault currents are affected by control loops, fault types, fault distance and nonlinear limiters. In particular, the influences of limiters on the fault model, fault current calculation and fault current characteristics were analyzed. Through detailed analysis, it was found that dynamics of the control loop cannot be ignored, the fault type and fault distance determine fault current level, and part of the limiters will totally change the fault current trend. Finally, calculation and experimental results verify the correctness of the proposed method.

A novel motion coordination method for variable-sized multi-mobile robots

Multi-mobile robot systems(MMRSs)are widely used for transportation in industrial scenes such as manufacturing and warehousing.In an MMRS,motion coordination is important as collisions and deadlocks may lead to losses or system stagnation.However,in some scenarios,robot sizes are different when loaded and unloaded,which means that the robots are variable-sized,making motion coordination more difficult.The methods based on zone control need to first divide the environment into disjoint zones,and then allocate the zones statically or dynamically for motion coordination.The zone-control-based methods are not accurate enough for variable-sized multi-mobile robots and reduce the efficiency of the system.This paper describes a motion coordination method based on glued nodes,which can dynamically avoid collisions and deadlocks according to the roadmap structure and the real-time paths of robots.Dynamic features make this method directly applicable to various scenarios,instead of dividing a roadmap into disjoint zones.The proposed method has been applied to many industrial projects,and this study is based on some manufacturing projects for experiments.Theoretical analysis and experimental results show that the proposed algorithm is effective and efficient.

The IL-1R/TLR signaling pathway is essential for efficient CD8+ T-cell responses against hepatitis B virus in the hydrodynamic injection mouse model

The outcome of hepatitis B viral(HBV)infection is determined by the complex interactions between replicating HBV and the immune system.While the role of the adaptive immune system in the resolution of HBV infection has been studied extensively,the contribution of innate immune mechanisms remains to be defined.Here we examined the role of the interleukin-1 receptor/Toll-like receptor(IL-1R/TLR)signaling pathway in adaptive immune responses and viral clearance by exploring the HBV mouse model.Hydrodynamic injection with a replication-competent HBV genome was performed in wild-type mice(WT)and a panel of mouse strains lacking specific innate immunity component expression.We found higher levels of HBV protein production and replication in Tlr2^(?/?),Tlr23479^(?/?),3d/Tlr24^(?/?),Myd88/Trif^(?/?)and Irak4^(?/?)mice,which was associated with reduced HBV-specific CD8+T-cell responses in these mice.Importantly,HBV clearance was delayed for more than 2 weeks in 3d/Tlr24^(?/?),Myd88/Trif^(?/?)and Irak4^(?/?)mice compared to WT mice.HBV-specific CD8+T-cell responses were functionally impaired for producing the cytokines IFN-γ,TNF-αand IL-2 in TLR signaling-deficient mice compared to WT mice.In conclusion,the IL-1R/TLR signaling pathway might contribute to controlling HBV infection by augmenting HBV-specific CD8+T-cell responses.

Sediment microbial fuel cell with floating biocathode for organic removal and energy recovery

A sediment microbial fuel cell （SMFC） with three dimensional floating biocathode （FBC） was developed for the electricity generation and biodegradation of sediment organic matter in order to avoid negative effect of dissolved oxygen （DO） depletion in aqueous environments on cathode performance and search cost-effective cathode materials. The biocathode was made from graphite granules with microbial attachment to replace platinum （Pt）-coated carbon paper cathode in a laboratory-scale SMFC （3 L in volume） filled with river sediment （organic content 49±4 g. kg^-1 dry weight）. After start-up of 10 days, the maximum power density of 1.00W.m^-3 （based on anode volume） was achieved. The biocathode was better than carbon paper cathode catalyzed by Pt. The attached biofilm on cathode enhanced power generation significantly. The FBC enhanced SMFC performance further in the presence aeration. The SMFC was continuously operated for an over 120-day period. Power generation peaked within 24 days, declined gradually and stabilized at a level of 1/6 peak power output. At the end, the sediment organic matter content near the anode was removed by 29% and the total electricity generated was equal to 0.251 g of chemical oxygen demand （COD） removed.

Modified pretreatment method for total microbial DNA extraction from contaminated river sediment

Extraction of high-quality microbial DNA from contaminated environmental samples is an essential step in microbial ecological study. Based on previously published methods for soil and sediment samples, a modified pretreatrnent method was developed for extracting microbial DNA from heavily contaminated river sediment samples via selection of optimal pretreatment parameters （i.e., reagent solution, reaction duration, and temperature）. The pretreatment procedure involves wash ing the river sediment sample for three times with a solution containing 0.1 mol.L-1 ethylene diamine tetra- acetic acid （EDTA）, 0.1 mol- L-1 Tris （pH 8.0）, 1.5 mol. L1 NaC1, 0.1 mol. L-1 NaH2PO4, and Na2HPO4 at 65~C with 180r.min-1 for 15min to remove humic materials and heavy metals prior to the employment of standard DNA extraction procedures. We compared the results of standard procedure DNA extraction following pretreatrnent, without pretreatment, and with using a commercial PowerSoilTM DNA Isolation Kit. The results indicated that the pretreatment significantly improved the DNA quality based on DNA yield, DNA fragment length, and determination of prokaryotic diversity. Prokaryotic diversity exhibited in the DNA with the pretreatment was also considerably higher than that extracted with the Power- SoilTM DNA Isolation Kit only. The pretreatment method worked well even with a small amount of sediment sample （0.25 g or even lower）. The method provides a novel, simple, cost-effective tool for DNA extraction for microbial community analysis in environmental monitoring and remediation processes.