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Pedestrian flow through exit:Study focused on evacuation pattern
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作者 张博思 余志红 +2 位作者 孙柏林 郭紫钰 陈默 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第1期755-764,共10页
Experiments are conducted on the evacuation rate of pedestrians through exits with queued evacuation pattern and random evacuation pattern. The experimental results show that the flow rate of pedestrians is larger wit... Experiments are conducted on the evacuation rate of pedestrians through exits with queued evacuation pattern and random evacuation pattern. The experimental results show that the flow rate of pedestrians is larger with the random evacuation pattern than with the queued evacuation pattern. Therefore, the exit width calculated based on the minimum evacuation clear width for every 100 persons, which is on the assumption that the pedestrians pass through the exit in one queue or several queues, is conservative. The number of people crossing the exit simultaneously is greater in the random evacuation experiments than in the queued evacuation experiments, and the time interval between the front row and rear row of people is shortened in large-exit conditions when pedestrians evacuate randomly. The difference between the flow rate with a queued evacuation pattern and the flow rate with a random evacuation pattern is related to the surplus width of the exit, which is greater than the total width of all accommodated people streams. Two dimensionless quantities are defined to explore this relationship. It is found that the difference in flow rate between the two evacuation patterns is stable at a low level when the surplus width of the exit is no more than 45% of the width of a single pedestrian stream. There is a great difference between the flow rate with the queued evacuation pattern and the flow rate with the random evacuation pattern in a scenario with a larger surplus width of the exit. Meanwhile, the pedestrians crowd extraordinarily at the exit in these conditions as well, since the number of pedestrians who want to evacuate through exit simultaneously greatly exceeds the accommodated level. Therefore, the surplus width of exit should be limited especially in the narrow exit condition, and the relationship between the two dimensionless quantities mentioned above could provide the basis to some extent. 展开更多
关键词 EVACUATION exit width flow rate queued evacuation pattern random evacuation pattern
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Heat and mass transfer of a circular porous moist object located in a triangular shaped vented cavity
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作者 SELIMEFENDIGIL Fatih OZCAN COBAN Seda OZTOP Hakan F 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第6期1956-1972,共17页
Heat and mass transfer of a circular-shaped porous moist object inside a two-dimensional triangle cavity is investigated by using finite element method.The porous object is considered to be a moist food sample,located... Heat and mass transfer of a circular-shaped porous moist object inside a two-dimensional triangle cavity is investigated by using finite element method.The porous object is considered to be a moist food sample,located in the middle of the cavity with inlet and outlet ports with different configurations of inlet/outlet ports.Convective drying performance is numerically assessed for different values of Reynolds numbers(between 50 and 250),dry air inlet temperature(between 40 and 80℃)and different locations of the port.It is observed that changing the port locations has significant impacts on the flow recirculaitons inside the triangular chamber while convective drying performance is highly affected.The moisture content reduces with longer time and for higher Reynolds number(Re)values.Case P4 where inlet and outlet ports are in the middle of the walls provides the most effective configuration in terms of convective drying performance while the worst case is seen for P1 case where inlet and outlet are closer to the corners of the chamber.There is a 192% difference between the moisture reduction of these two cases at Re=250,T=80℃ and t=120 min. 展开更多
关键词 convective drying porous domain cavity flow inlet/exit port finite element method
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A novel cascaded H-bridge photovoltaic inverter with flexible arc suppression function
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作者 Junyi Tang Wei Gao 《Global Energy Interconnection》 EI CSCD 2024年第4期513-527,共15页
This paper presents a novel approach that simultaneously enables photovoltaic(PV)inversion and flexible arc suppression during single-phase grounding faults.Inverters compensate for ground currents through an arc-elim... This paper presents a novel approach that simultaneously enables photovoltaic(PV)inversion and flexible arc suppression during single-phase grounding faults.Inverters compensate for ground currents through an arc-elimination function,while outputting a PV direct current(DC)power supply.This method effectively reduces the residual grounding current.To reduce the dependence of the arc-suppression performance on accurate compensation current-injection models,an adaptive fuzzy neural network imitating a sliding mode controller was designed.An online adaptive adjustment law for network parameters was developed,based on the Lyapunov stability theorem,to improve the robustness of the inverter to fault and connection locations.Furthermore,a new arc-suppression control exit strategy is proposed to allow a zerosequence voltage amplitude to quickly and smoothly track a target value by controlling the nonlinear decrease in current and reducing the regulation time.Simulation results showed that the proposed method can effectively achieve fast arc suppression and reduce the fault impact current in single-phase grounding faults.Compared to other methods,the proposed method can generate a lower residual grounding current and maintain good arc-suppression performance under different transition resistances and fault locations. 展开更多
关键词 Photovoltaic inverter Flexible arc suppression Adaptive control Fuzzy neural network Sliding mode control Exit strategy
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Regarding the Regulatory Sandbox Route and Mechanism for Governance of Artificial Intelligence
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作者 Ye Xuanhan 《科技与法律(中英文)》 CSSCI 2024年第5期136-148,共13页
The main challenge in AI governance today is striking a balance between controlling AI dangers and fostering AI innovation.Regulators in a number of nations have progressively extended the regulatory sandbox,which was... The main challenge in AI governance today is striking a balance between controlling AI dangers and fostering AI innovation.Regulators in a number of nations have progressively extended the regulatory sandbox,which was first implemented in the banking sector,to AI governance in an effort to reduce the conflict between regulation and innovation.The AI regulatory sandbox is a new and feasible route for AI governance in China that not only helps to manage the risks of technology application but also prevents inhibiting AI innovation.It keeps inventors'trial-and-error tolerance space inside the regulatory purview while offering a controlled setting for the development and testing of novel AI that hasn't yet been put on the market.By providing full-cycle governance of AI with the principles of agility and inclusive prudence,the regulatory sandbox offers an alternative to the conventional top-down hard regulation,expost regulation,and tight regulation.However,the current system also has inherent limitations and practical obstacles that need to be overcome by a more rational and effective approach.To achieve its positive impact on AI governance,the AI regulatory sandbox system should build and improve the access and exit mechanism,the coordination mechanism between the sandbox and personal information protection,and the mechanisms of exemption,disclosure,and communication. 展开更多
关键词 artificial intelligence governance regulatory sandbox agile regulation inclusive prudential regulation access and exit mechanism coordination mechanism
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Application of Connected Truck Data to Evaluate Spatiotemporal Impact of Rest Area Closures on Ramp Parking
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作者 Jijo K. Mathew Jairaj Desai +1 位作者 Edward D. Cox Darcy M. Bullock 《Journal of Transportation Technologies》 2024年第3期289-307,共19页
Ensuring adequate access to truck parking is critical to the safe and efficient movement of freight traffic. There are strict federal guidelines for commercial truck driver rest periods. Rest areas and private truck s... Ensuring adequate access to truck parking is critical to the safe and efficient movement of freight traffic. There are strict federal guidelines for commercial truck driver rest periods. Rest areas and private truck stops are the only places for the trucks to stop legally and safely. In locations without sufficient parking areas, trucks often park on interstate ramps, which create safety risks for other interstate motorists. Historically, agencies have employed costly and time intensive manual counting methods, camera surveillance, and driver surveys to assess truck parking. Connected truck data, available in near real-time, offers an efficient alternative to practitioners to assess truck parking patterns and identify areas where there may be insufficient safe parking spaces. This paper presents a case study of interstate I-70 in east central Indiana and documents the observed spatiotemporal impacts of a rest area closure on truck parking on nearby interstate ramps. Results showed that there was a 28% increase in parking on ramps during the rest area closure. Analysis also found that ramps closest to the rest area were most impacted by the closure, seeing a rise in truck parking sessions as high as 2.7 times. Parking duration on the ramps during rest area closure also increased drastically. Although it was expected that this would result in increased parking by trucks on adjacent ramps, this before, during, after scenario provided an ideal scenario to evaluate the robustness of these techniques to assess changing parking characteristics of long-haul commercial trucks. The data analytics and visualization tools presented in this study are scalable nationwide and will aid stakeholders in informed data-driven decision making when allocating resources towards improving the nations commercial vehicle parking infrastructure. 展开更多
关键词 Connected Truck Data Rest Areas Exit Ramps Truck Parking Commercial Vehicles
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nvestigating the role of exiting vehicles and turn indicator usage in gap acceptance at single-lane roundabouts
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作者 Nathan P. BELZ 《Frontiers of Structural and Civil Engineering》 SCIE EI CSCD 2017年第1期8-16,共9页
Roundabouts are becoming a preferred form of intersection control type due to their safety and capacity benefits. Yield control at roundabout entries inherently reduces fuel consumption and emissions when compared to ... Roundabouts are becoming a preferred form of intersection control type due to their safety and capacity benefits. Yield control at roundabout entries inherently reduces fuel consumption and emissions when compared to other conventional intersection types. However, these benefits can be limited by poor driver behavior and judgment when entering the roundabout. This research addresses the nature of gap distributions and use of turn indicators by exiting vehicles at three single-lane roundabouts in Vermont, New York, and Alaska. Presented here is a comparison of vehicle headways measured at two different locations in each roundabout. Rejected headways are analyzed in the context of priority abstaining events when entering drivers yield to vehicles exiting on the same leg of the roundabout suggesting that "true" critical gaps are being overestimated. Results indicate that exiting vehicles, particularly those that do not use their turn indicators when departing from the major-stream of traffic have an influence on the entry decision of drivers on the same approach. This behavior is of particular concern for intersection efficiency (i.e., delay) and sustainability (i.e., excess fuel consumption and emissions). Results prompt the consideration of more consistent guidance on and enforcement of turn indicator use during roundabout negotiations. 展开更多
关键词 roundabouts exiting vehicles turn indicator use headways
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Research on visual differences of exits of different grades of tunnels based on machine learning
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作者 Fangtong Jiao Zhenwei Shi +2 位作者 Lingyu Li Wenpin Xu Qing Lan 《Digital Transportation and Safety》 2024年第3期75-81,共7页
Tunnels are vital in connecting crucial transportation hubs as transportation infrastructure evolves.Variations in tunnel design standards and driving conditions across different levels directly impact driver visual p... Tunnels are vital in connecting crucial transportation hubs as transportation infrastructure evolves.Variations in tunnel design standards and driving conditions across different levels directly impact driver visual perception and traffic safety.This study employs a Gaussian hybrid clustering machine learning model to explore driver gaze patterns in highway tunnels and exits.By utilizing contour coefficients,the optimal number of classification clusters is determined.Analysis of driver visual behavior across tunnel levels,focusing on gaze point distribution,gaze duration,and sweep speed,was conducted.Findings indicate freeway tunnel exits exhibit three distinct fixation point categories aligning with Gaussian distribution,while highway tunnels display four such characteristics.Notably,in both tunnel types,65%of driver gaze is concentrated on the near area ahead of their lane.Differences emerge in highway tunnels due to oncoming traffic,leading to 13.47%more fixation points and 0.9%increased fixation time in the right lane compared to regular highway tunnel conditions.Moreover,scanning speeds predominantly fall within the 0.25-0.3 range,accounting for 75.47%and 31.14%of the total sweep speed. 展开更多
关键词 Traffic safety Tunnel exit Machine learning model Fixation characteristics Scanning characteristics
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Exiting Afghanistan
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作者 LI YAN 《Beijing Review》 2011年第29期14-15,共2页
The United States prepares to begin withdrawing troops from Afghanistan U.S. President Barack Obama outlined steps for the
关键词 exiting Afghanistan
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Diffusion occupation time before exiting 被引量:10
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作者 Yingqiu LI Suxin WANG +1 位作者 Xiaowen ZHOU Na ZHU 《Frontiers of Mathematics in China》 SCIE CSCD 2014年第4期843-861,共19页
Using the approach of D. Landriault et al. and B. Li and X. Zhou, for a one-dimensional time-homogeneous diffusion process X and constants c 〈 a 〈 b 〈 d, we find expressions of double Laplace transforms of the form... Using the approach of D. Landriault et al. and B. Li and X. Zhou, for a one-dimensional time-homogeneous diffusion process X and constants c 〈 a 〈 b 〈 d, we find expressions of double Laplace transforms of the form Ex[e--θTd--λ∫o Td1a 〈Xs〈b ds; Td 〈 Tc], where Tx denotes the first passage time of level x. As applications, we find explicit Laplace transforms of the corresponding occupation time and occupation density for the Brownian motion with two-valued drift and that of occupation time for the skew Ornstein- Uhlenbeck process, respectively. Some known results are also recovered. 展开更多
关键词 DIFFUSION exit problem occupation time occupation density localtime Brownian motion with two-valued drift skew Ornstein-Uhlenbeck (OU)process
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Effect of a static pedestrian as an exit obstacle on evacuation 被引量:2
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作者 胡杨慧 毕钰帛 +3 位作者 张俊 练丽萍 宋卫国 高伟 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第1期615-625,共11页
Building exit as a bottleneck structure is the last and the most congested stage in building evacuation.It is well known that obstacles at the exit affect the evacuation process,but few researchers pay attention to th... Building exit as a bottleneck structure is the last and the most congested stage in building evacuation.It is well known that obstacles at the exit affect the evacuation process,but few researchers pay attention to the effect of stationary pedestrians(the elderly with slow speed,the injured,and the static evacuation guide)as obstacles at the exit on the evacuation process.This paper explores the influence of the presence of a stationary pedestrian as an obstacle at the exit on the evacuation from experiments and simulations.We use a software,Pathfinder,based on the agent-based model to study the effect of ratios of exit width(D)to distance(d)between the static pedestrian and the exit,the asymmetric structure by shifting the static pedestrian upward,and types of obstacles on evacuation.Results show that the evacuation time of scenes with a static pedestrian is longer than that of scenes with an obstacle due to the unexpected hindering effect of the static pedestrian.Different ratios of D/d have different effects on evacuation efficiency.Among the five D/d ratios in this paper,the evacuation efficiency is the largest when d is equal to 0.75D,and the existence of the static pedestrian has a positive impact on evacuation in this condition.The influence of the asymmetric structure of the static pedestrian on evacuation efficiency is affected by D/d.This study can provide a theoretical basis for crowd management and evacuation plan near the exit of complex buildings and facilities. 展开更多
关键词 EVACUATION exit obstacle static pedestrian pathfinder simulation
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Exit strategies in inflammatory bowel disease:Looking beyond antitumor necrosis factors 被引量:1
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作者 Federica Crispino Andrea Michielan +4 位作者 Mauro Grova Chiara Tieppo Marta Mazza Teresa Marzia Rogger Franco Armelao 《World Journal of Clinical Cases》 SCIE 2023年第12期2657-2669,共13页
The long-term management of patients with inflammatory bowel disease(IBD)is still a matter of debate,and no clear guidelines have been issued.In clinical practice,gastroenterologists often have to deal with patients i... The long-term management of patients with inflammatory bowel disease(IBD)is still a matter of debate,and no clear guidelines have been issued.In clinical practice,gastroenterologists often have to deal with patients in prolonged remission after immunomodulatory or immunosuppressive therapies.When planning an exit strategy for drug withdrawal,the risk of disease relapse must be balanced against the risk of drug-related adverse events and healthcare costs.Furthermore,there is still a dearth of data on the withdrawal of novel biologics,such as the anti-α4β7 integrin antibody(vedolizumab)and anti-IL12/23 antibody(ustekinumab),as well as the small molecule tofacitinib.Models for estimating the risk of disease relapse and the efficacy of retreatment should be evaluated according to the patient's age and IBD phenotype.These models should guide clinicians in programming a temporary drug withdrawal after discussing realistic outcomes with the patient.This would shift the paradigm from an exit strategy to a holiday strategy. 展开更多
关键词 Exit strategy Biologic withdrawal Drug holiday Vedolizumab USTEKINUMAB Tofacitinib
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Effect of CICARE communication nursing model combined with motivational psychological intervention in patients with postintensive care unit syndrome 被引量:4
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作者 Sun-Ju She Ying-Ying Xu 《World Journal of Psychiatry》 SCIE 2023年第9期707-713,共7页
BACKGROUND Post-intensive care syndrome(PICS)is a term used to describe a constellation of new or worsened dysfunctions in the physical,cognitive,or mental health status of critically ill patients after their discharg... BACKGROUND Post-intensive care syndrome(PICS)is a term used to describe a constellation of new or worsened dysfunctions in the physical,cognitive,or mental health status of critically ill patients after their discharge from the intensive care unit(ICU).These dysfunctions persist beyond the acute phase of illness and have a significant impact on both the patient and their family.Connect,Introduce,Communicate,Ask,Respond,Exit(CICARE)communication advocates that patients should be respected and accepted when receiving medical services.Clinicians should attach importance to the communication mode of feelings,including connection,introduction,communication,ask,response,and exit 6 steps.AIM To assess the impact of CICARE communication on the reduction of anxiety,depression,and post-traumatic stress disorder(PTSD)symptoms in patients transitioning from the ICU to other care settings.METHODS This prospective,randomized,controlled study was performed between October 2021 and March 2023.Intensive Care Unit Memory Tool was used to evaluate patients’ICU memory.The Hospital Anxiety and Depression Scale was employed to determine the presence of anxiety or depression symptoms.Impact of Event Scale-Revised was utilized to assess the presence of PTSD.All data were processed and analyzed using R language software version 4.1.0.The measurement data were expressed as mean±SD,and the t test was used.The count data were analyzed by theχ2 test and expressed as[n(%)].RESULTS In total,248 subjects were included in this study.Among them,206 were successfully followed up for three months after transfer from the ICU,and 42 cases were lost to follow-up.There was no significant difference in the composition of ICU memory between the two groups.The application of the CICARE communication nursing model combined with the motivational psychological intervention nursing model,as well as the adoption of only the motivational psychological intervention nursing model,demonstrated favorable effects on PICS.Both groups of patients showed a reduction in anxiety scores,depression scores,and PTSD scores following the implementation of these two nursing models.However,it is noteworthy that the experimental group exhibited greater improvements compared to the control group.CONCLUSION Our findings suggest that CICARE communication nursing mode may have good influence on relieving PICS. 展开更多
关键词 Connect Introduce Communicate Ask Respond Exit Post-intensive care syndrome Motivational psychological intervention
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Exit problem of stochastic SIR model with limited medical resource
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作者 Y.C.Mao X.B.Liu 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2023年第1期8-13,共6页
Nonlinearity and randomness are both the essential attributes for the real world,and the case is the same for the models of infectious diseases,for which the deterministic models can not give a complete picture of the... Nonlinearity and randomness are both the essential attributes for the real world,and the case is the same for the models of infectious diseases,for which the deterministic models can not give a complete picture of the evolution.However,although there has been a lot of work on stochastic epidemic models,most of them focus mainly on qualitative properties,which makes us somewhat ignore the original meaning of the parameter value.In this paper we extend the classic susceptible-infectious-removed(SIR)epidemic model by adding a white noise excitation and then we utilize the large deviation theory to quantitatively study the long-term coexistence exit problem with epidemic.Finally,in order to extend the meaning of parameters in the corresponding deterministic system,we tentatively introduce two new thresholds which then prove rational. 展开更多
关键词 Stochastic epidemic model Stochastic dynamical system Large deviation theory Exit problem
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The asymptotic relation between the first crossing point and the last exit time of Gaussian order statistics sequences
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作者 NING Zi-jun TAN Zhong-quan 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2023年第4期545-561,共17页
In this paper,we study the asymptotic relation between the first crossing point and the last exit time for Gaussian order statistics which are generated by stationary weakly and strongly dependent Gaussian sequences.I... In this paper,we study the asymptotic relation between the first crossing point and the last exit time for Gaussian order statistics which are generated by stationary weakly and strongly dependent Gaussian sequences.It is shown that the first crossing point and the last exit time are asymptotically independent and dependent for weakly and strongly dependent cases,respectively.The asymptotic relations between the first crossing point and the last exit time for stationary weakly and strongly dependent Gaussian sequences are also obtained. 展开更多
关键词 rst crossing point last exit time stationary Gaussian sequences Gaussian order statistic se-quences
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Clicking through the Clickstream: A Novel Statistical Modeling Approach to Improve Information Usage of Clickstream Data by E-Commerce Entities
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作者 Corban Allenbrand 《Intelligent Information Management》 2023年第3期180-215,共36页
Success or failure of an E-commerce platform is often reduced to its ability to maximize the conversion rate of its visitors. This is commonly regarded as the capacity to induce a purchase from a visitor. Visitors pos... Success or failure of an E-commerce platform is often reduced to its ability to maximize the conversion rate of its visitors. This is commonly regarded as the capacity to induce a purchase from a visitor. Visitors possess individual characteristics, histories, and objectives which complicate the choice of what platform features that maximize the conversion rate. Modern web technology has made clickstream data accessible allowing a complete record of a visitor’s actions on a website to be analyzed. What remains poorly constrained is what parts of the clickstream data are meaningful information and what parts are accidental for the problem of platform design. In this research, clickstream data from an online retailer was examined to demonstrate how statistical modeling can improve clickstream information usage. A conceptual model was developed that conjectured relationships between visitor and platform variables, visitors’ platform exit rate, boune rate, and decision to purchase. Several hypotheses on the nature of the clickstream relationships were posited and tested with the models. A discrete choice logit model showed that the content of a website, the history of website use, and the exit rate of pages visited had marginal effects on derived utility for the visitor. Exit rate and bounce rate were modeled as beta distributed random variables. It was found that exit rate and its variability for pages visited were associated with site content, site quality, prior visitor history on the site, and technological preferences of the visitor. Bounce rate was also found to be influenced by the same factors but was in a direction opposite to the registered hypotheses. Most findings supported that clickstream data is amenable to statistical modeling with interpretable and comprehensible models. 展开更多
关键词 Business Intelligence Intelligent Information Management Web Analytics Web Technology Management Exit Rate Bounce Rate Online Consumer Model Discrete Choice Model
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Globalization Under the Spells of Breakdowns in Supply Chains, Regime Change, Regime Formation, and Alliance Restructuring: How Much Is Left for Public Goods?
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作者 Ekkart Zimmermann 《International Relations and Diplomacy》 2023年第5期211-216,共6页
In a paper conceived about five years ago(“Globalization and Public Goods:Too Big to Tackle?”)roughly a dozen factors were linked to explain important causal paths from globalization to the potential output of publi... In a paper conceived about five years ago(“Globalization and Public Goods:Too Big to Tackle?”)roughly a dozen factors were linked to explain important causal paths from globalization to the potential output of public goods.The Russian invasion of Ukraine,the corona epidemic,and the increased hegemonic rivalry between China and the U.S.interrupted or even destroyed many of the linkages between globalization and potential public good production.About five important detrimental paths involved in the meantime.In the present article we aim at linking what is left from the previous level of globalization or emerging to form a new and simplified causal model for likely linkages between truncated or(re-)emerging globalization,and the deadly needed output of public goods.These linkages refer to rules of climate control,go to trade linkages and arbitrary tariffs and trade interventions.Regime change,regime formation,and alliance restructuring address aspects of domestic rule and international stability.Selectorate theory,regime type,and exit options for political elites provide key explanatory factors in explaining globalization and public goods productions,or their decay.Where possible we use some data and transformation experiences corroborating our arguments.In other instances need for further empirical macro research will become clear. 展开更多
关键词 hegemonic rivalry new alliances and bloc formation de-globalization and re-globalization selectorate theory regime type and regime change elite exit options public goods
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Research on Traffic Safety at Tunnel Entrance and Exit
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作者 Jiawen Chu 《Journal of Architectural Research and Development》 2023年第1期1-7,共7页
Highway tunnel entrances have a high rate of expressway traffic accidents.In this paper,the reasons for the high incidence of traffic accidents at highway tunnel entrances are analyzed in detail,and corresponding solu... Highway tunnel entrances have a high rate of expressway traffic accidents.In this paper,the reasons for the high incidence of traffic accidents at highway tunnel entrances are analyzed in detail,and corresponding solutions are proposed,hoping to provide some reference to relevant parties. 展开更多
关键词 EXPRESSWAY Tunnel entrance and exit Traffic safety Improvement measures
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Analysis of Interchange Exit Safety Technology
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作者 Shuai Li Zhonglei Yu Zhipan Yang 《Journal of World Architecture》 2023年第4期6-10,共5页
In order to improve the safety of the exit of expressway interchanges,the main problems and influencing factors of interchange exits are analyzed according to the number of traffic accidents at expressway interchange ... In order to improve the safety of the exit of expressway interchanges,the main problems and influencing factors of interchange exits are analyzed according to the number of traffic accidents at expressway interchange exits in China.Some suggestions and countermeasures are then put forward from the aspect of safety technology for future reference. 展开更多
关键词 INTERCHANGE Exit safety Safety guarantee
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具有不等错误保护特性的LDPC编码调制方案 被引量:4
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作者 张玉玲 袁东风 程翔 《通信学报》 EI CSCD 北大核心 2006年第12期98-102,共5页
针对LDPC(low-densityparity-check)编码调制系统,提出了一种新的具有不等错误保护特性的调制方案,在一个码字内,利用不同的调制方式对于重要的比特给予较强的保护,对于次要的比特给予较弱的保护,该方案既适用于非规则LDPC码,也适用于规... 针对LDPC(low-densityparity-check)编码调制系统,提出了一种新的具有不等错误保护特性的调制方案,在一个码字内,利用不同的调制方式对于重要的比特给予较强的保护,对于次要的比特给予较弱的保护,该方案既适用于非规则LDPC码,也适用于规则LDPC码。计算机仿真结果表明,新方案的性能是传统16QAM及4QAM的折衷,当采用1/2码率时,其频带利用率与8PSK相同,但是误码率性能优于8PSK。新方案的性能优于现有文献中基于比特可靠性的调制映射方案,并采用EXIT(extrinsicinformationtransfer)图对新方案的优异性能给出了解释。 展开更多
关键词 LDPC码 不等错误保护 EXIT图
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一种AWGN信道下非规则LDPC码的优化方法 被引量:5
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作者 毛倩 董德存 曾小清 《计算机应用》 CSCD 北大核心 2010年第2期292-294,共3页
提出了一种加性高斯噪声(AWGN)信道下非规则低密度奇偶校验(LDPC)码的优化方法。利用LDPC码迭代译码算法下变量节点与校验节点的EX IT曲线之间的面积反映码的收敛阈值与香农限的差距这一特点,设计表示两条EX IT曲线之间面积的函数F,该... 提出了一种加性高斯噪声(AWGN)信道下非规则低密度奇偶校验(LDPC)码的优化方法。利用LDPC码迭代译码算法下变量节点与校验节点的EX IT曲线之间的面积反映码的收敛阈值与香农限的差距这一特点,设计表示两条EX IT曲线之间面积的函数F,该函数可以衡量非规则LDPC码的性能,F值越小,LDPC码的收敛阈值就越接近香农限。仿真显示,合理设计变量节点和校验节点,减小函数F的值,能够提高非规则LDPC码的性能。 展开更多
关键词 低密度奇偶校验码 外部信息转换(EXIT)图 加性高斯白噪声 迭代译码 收敛阈值
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