The Spatial Variability of Vehicle Densities as Determinant of Urban Network Capacity

Due to the complexity of the traffic flow dynamics in urban road networks, most quantitative descriptions of city traffic so far are based on computer simulations. This contribution pursues a macroscopic (fluid-dynamic) simulation approach, which facilitates a simple simulation of congestion spreading in cities. First, we show that a quantization of the macroscopic turning flows into units of single vehicles is necessary to obtain realistic fluctuations in the traffic variables, and how this can be implemented in a fluid-dynamic model. Then, we propose a new method to simulate destination flows without the requirement of individual route assignments. Combining both methods allows us to study a variety of different simulation scenarios. These reveal fundamental relationships between the average flow, the average density, and the variability of the vehicle densities. Considering the inhomogeneity of traffic as an independent variable can eliminate the scattering of congested flow measurements. The variability also turns out to be a key variable of urban traffic performance. Our results can be explained through the number of full links of the road network, and approximated by a simple analytical formula

Exploiting citation networks for large-scale author name disambiguation

We present a novel algorithm and validation method for disambiguating author names in very large bibliographic data sets and apply it to the full Web of Science (WoS) citation index. Our algorithm relies only upon the author and citation graphs available for the whole period covered by the WoS. A pair-wise publication similarity metric, which is based on common co-authors, self-citations, shared references and citations, is established to perform a two-step agglomerative clustering that first connects individual papers and then merges similar clusters. This parameterized model is optimized using an h-index based recall measure, favoring the correct assignment of well-cited publications, and a name-initials-based precision using WoS metadata and cross-referenced Google Scholar profiles. Despite the use of limited metadata, we reach a recall of 87% and a precision of 88% with a preference for researchers with high h-index values. 47 million articles of WoS can be disambiguated on a single machine in less than a day. We develop an h-index distribution model, confirming that the prediction is in excellent agreement with the empirical data, and yielding insight into the utility of the h-index in real academic ranking scenarios.Comment: 14 pages, 5 figure

Operation regimes and slower-is-faster effect in the controlof traffic intersections

The efficiency of traffic flows in urban areas is known to crucially depend on signal operation. Here, elements of signal control are discussed, based on the minimization of overall travel times or vehicle queues. Interestingly, we find different operation regimes, some of which involve a "slower-is-faster effect”, where a delayed switching reduces the average travel times. These operation regimes characterize different ways of organizing traffic flows in urban road networks. Besides the optimize-one-phase approach, we discuss the procedure and advantages of optimizing multiple phases as well. To improve the service of vehicle platoons and support the self-organization of "green waves”, it is proposed to consider the price of stopping newly arriving vehicle

Operation Regimes and Slower-is-Faster-Effect in the Control of Traffic Intersections

The efficiency of traffic flows in urban areas is known to crucially depend on signal operation. Here, elements of signal control are discussed, based on the minimization of overall travel times or vehicle queues. Interestingly, we find different operation regimes, some of which involve a "slower-is-faster effect", where a delayed switching reduces the average travel times. These operation regimes characterize different ways of organizing traffic flows in urban road networks. Besides the optimize-one-phase approach, we discuss the procedure and advantages of optimizing multiple phases as well. To improve the service of vehicle platoons and support the self-organization of "green waves", it is proposed to consider the price of stopping newly arriving vehicles.Comment: For related work see http://www.helbing.or

An Investigation into the Effective Factors on the Intention to Commercialization of Knowledge in a University: A Case Study

The purpose of this study was to provide a causal model for factors affecting the commercialization of academic research. This study is applied research in terms of purpose and a descriptive study of correlation type in terms of method. The statistical population consists of 499 graduate students at Engineering School of Shiraz University. The data gathering tool was a questionnaire. Cronbach’s alpha coefficient was used to assess its reliability. In this research, the effect of following variables on attitude to the commercialization of Knowledge (ACK) of knowledge is investigated: psychological empowerment (PE), self-efficacy, university policy (UP), social capital (SC), and perceived behavioral al control. The results of this study, based on the obtained correlation coefficients, show that the intention to the commercialization of Knowledge (ICK) has a separate and significant relation with PE, perceived behavioral control (PBC) and ACK at the level of 0.01 and with the SC variable at the level of 0.05. Furthermore, the ICK has no significant relationship with self-efficacy and UP

Persistence and Uncertainty in the Academic Career

Understanding how institutional changes within academia may affect the overall potential of science requires a better quantitative representation of how careers evolve over time. Since knowledge spillovers, cumulative advantage, competition, and collaboration are distinctive features of the academic profession, both the employment relationship and the procedures for assigning recognition and allocating funding should be designed to account for these factors. We study the annual production n_{i}(t) of a given scientist i by analyzing longitudinal career data for 200 leading scientists and 100 assistant professors from the physics community. We compare our results with 21,156 sports careers. Our empirical analysis of individual productivity dynamics shows that (i) there are increasing returns for the top individuals within the competitive cohort, and that (ii) the distribution of production growth is a leptokurtic "tent-shaped" distribution that is remarkably symmetric. Our methodology is general, and we speculate that similar features appear in other disciplines where academic publication is essential and collaboration is a key feature. We introduce a model of proportional growth which reproduces these two observations, and additionally accounts for the significantly right-skewed distributions of career longevity and achievement in science. Using this theoretical model, we show that short-term contracts can amplify the effects of competition and uncertainty making careers more vulnerable to early termination, not necessarily due to lack of individual talent and persistence, but because of random negative production shocks. We show that fluctuations in scientific production are quantitatively related to a scientist's collaboration radius and team efficiency.Comment: 29 pages total: 8 main manuscript + 4 figs, 21 SI text + fig

Smart food waste management : embedded machine learning vs cloud based solutions

In Switzerland, 2.8 million tons of food are lost or wasted across all stages of food production - every year. This equates to approximately 330 kg of food waste per person. By analysing and classifying discarded food with a smart waste analysis system combined with machine learning, valuable insights can be gained and the amount of wasted food can be significantly reduced. In this paper, we present how we have developed an embedded system which helps to solve this task. The embedded system operates in a decentralized manner: It captures an image every time food is thrown into a bin. The discarded food is identified and classified with machine learning algorithms. This provides a detailed insight into the structure of food waste for customers, e.g. restaurants or canteens. We implemented the machine learning algorithm directly on the embedded systems control unit. We found that running machine learning directly on embedded devices has many advantages compared to running them in the cloud: We saved significant amounts of cloud storage and reduced power consumption by up to a factor 100. In addition, privacy was increased and required bandwidth reduced because only the machine learning results are forwarded to the cloud, not the full data

A three-dimensional macroscopic fundamental diagram for mixed bi-modal urban networks

Recent research has studied the existence and the properties of a macroscopic fundamental diagram (MFD) for large urban networks. The MFD should not be universally expected as high scatter or hysteresis might appear for some type of networks, like heterogeneous networks or freeways. In this paper, we investigate if aggregated relationships can describe the performance of urban bi-modal networks with buses and cars sharing the same road infrastructure and identify how this performance is influenced by the interactions between modes and the effect of bus stops. Based on simulation data, we develop a three-dimensional vehicle MFD (3D-vMFD) relating the accumulation of cars and buses, and the total circulating vehicle flow in the network. This relation experiences low scatter and can be approximated by an exponential-family function. We also propose a parsimonious model to estimate a three-dimensional passenger MFD (3D-pMFD), which provides a different perspective of the flow characteristics in bi-modal networks, by considering that buses carry more passengers. We also show that a constant Bus-Car Unit (BCU) equivalent value cannot describe the influence of buses in the system as congestion develops. We then integrate a partitioning algorithm to cluster the network into a small number of regions with similar mode composition and level of congestion. Our results show that partitioning unveils important traffic properties of flow heterogeneity in the studied network. Interactions between buses and cars are different in the partitioned regions due to higher density of buses. Building on these results, various traffic management strategies in bi-modal multi-region urban networks can then be integrated, such as redistribution of urban space among different modes, perimeter signal control with preferential treatment of buses and bus priority

Causal Model of the Association between Academic Burnout and Achievement Goals: The Intermediating Role of Self-Efficacy and Procrastination

Background & Objective: There has been growing recognition that medical students, interns, residents, and practicing physicians across many specialties are prone to burnout, with recent studies linking high rates of burnout to adverse mental health issues. The aim of this study was to examine factors affecting academic burnout among medical students and investigate the association between achievement goals and its dimensions, academic self-efficacy, and academic procrastination in the form of a causal model. Methods: For this purpose, 174 students (98 in the clinical stage and 76 in the preclinical stage) of Shiraz University of Medical Sciences (Iran) were selected based on Cochran’s Formula and through simple random sampling. The data collection tools consisted of the Maslach Burnout Inventory-Student Survey (MBI-SS), Achievement Goal Questionnaire (Elliot and McGregor), Academic Self-Efficacy Scale (Midgley et al.), and Academic Procrastination Scale (Savari). To analyze the data, path analysis and the Pearson correlation coefficient were used. Results: The resulting path models indicated that academic burnout had significant negative relationships with mastery achievement goal, performance-approach, and academic self-efficacy, but it had significantly positive relationships with academic procrastination and performanceavoidance. It was also found that achievement goals had impact on academic burnout through academic procrastination and self-efficacy. The explained variance of academic burnout was 0.61. Conclusion: It was found that achievement goals and academic self-efficacy had significant effects on academic procrastination and burnout. Thus, it is suggested that those involved in education provide the students with situations in which they can achieve a higher sense of empowerment in learning, so that they become more engaged in their academic work and be less likely to experience burnout. Key Words: Academic burnout, Achievement goals, Academic self-efficacy, Academic procrastinatio