Miracle-dz/UniFAR-FTUs huggingface dataset:
Using Social Media to Measure Temporal Ambient Population: Does it Help Explain Local Crime Rates?

A challenge for studies assessing routine activities theory is accounting for the spatial and temporal confluence of offenders and targets given that people move about during the daytime and nighttime. We propose exploiting social media (Twitter) data to construct estimates of the population at various locations at different times of day, and assess whether these estimates help predict the amount of crime during two-hour time periods over the course of the day. We address these questions using crime data for 97,428 blocks in the Southern California region, along with geocoded information on tweets in the region over an eight month period. The results show that this measure of the temporal ambient population helps explain the level of crime in blocks during particular time periods. The use of social media data appear promising for testing various implications of routine activities and crime pattern theories, given their explicit spatial and temporal nature.
Rank-Based Simulation on Acyclic Graphs

The simulation preorder is widely used both as a behavioral relation in concurrent systems, and as an abstraction tool to reduce the state space in model checking, were memory requirement is clearly a critical issue. Therefore, in this context a simulation algorithm should address both time and space efficiency. In this paper, we rely on the notion of rank to design an efficient simulation algorithm. It turns out that such algorithm outperforms—both in terms of time and in terms of space—the best simulation algorithms in the literature, on the class of acyclic graphs.
Research on E-Learning Supporting System: A Review from the Perspective of Knowledge Management

Knowledge management (KM) is supported by many strategies such as business intelligence, collaboration, document management and e-learning (E-L). Thus, it is urgent for organizations to design and develop an E-L system with advanced technologies. The review of basic technologies that support E-L will be in favor of further study on E-L. From perspective of KM, is paper makes a review about the definition of E-L, the relationship between E-L and KM and advanced technologies that support the design and operation of E-L system. Considering the importance of China in developing the technology of E-L, we especially introduce the current development condition of E-L in China. At the end of this paper, we analyze the main trends of the development direction of E-L technology.
Road detection and mapping using 3D rolling window

This paper presents a method of road detection and mapping using accumulated 3D data from 2D scans. The idea of 3D rolling window is introduced, and its probabilistic characteristics are studied. A cascaded road detection process is developed with region-growing and classification methods. A probabilistic framework is utilized for road mapping purposes with the detection results. The performance of detection and mapping algorithm is evaluated through experiments.
Adaptive intra modes reduction by clustering for H.264/AVC

H.264/AVC adopts intra coding technique to reduce spatial redundancies. In order to achieve better coding performance, there are nine candidate modes for 4×4 block unit to be selected by Rate-Distortion Optimization(RDO) process in the H.264/AVC encoder-side. However, too many intra candidate modes undoubtedly increase the transmitted bits that represent them. To solve this problem, a novel method for reducing the number of intra modes is proposed in this paper. For each 4 × 4 block, our algorithm can cluster the nine candidate modes into several groups and selects one mode from each group as a representative of all the modes in this group, so the cost of transmission can be reduced significantly because of the reduction of number of candidate modes. Experimental results show that the proposed method achieves 3.2% bit-rate reduction on average for various video sequences. The improvement of coding performance can be up to 7% bit-rate reduction at low bit rate, averagely.
Optimal Design of Filter Banks for Texture Discrimination

In this paper, we present an optimum design of two -band Finite Impulse Response (FIR) Quadrature Mirror Filter bank (QMF) for maximum possible discrimination between textured images. There are several applications, which may not require reconstruction of signal from its transformed coefficients e.g. texture analysis, remote sensing etc. For such applications, features are extracted at different frequency resolution scales. Hence, it is extremely important that transformed image coefficients should be distortion less, which is not possible in practice . Therefore, we present an optimal design method for maximum possible discrimination between any particular classes of textures with minimum possible coefficient error. In order to obtain the desired results, the optimization routine adjusts relative error weighting along with passband and stopband edges for the design of symmetric response FIR filter.
PERCEPCIÓN DE LOS ESTUDIANTES SOBRE EL VALOR DE LAS TIC EN SUS ESTRATEGIAS DE APRENDIZAJE Y SU RELACIÓN CON EL RENDIMIENTO

Actualmente la investigacion educativa se centra en la busqueda de evidencias que pongan de manifiesto la utilidad de las TIC (Tecnologias de la Informacion y Comunicacion) para la mejora del rendimiento academico de los universitarios. En esta linea, nuestra investigacion pretende conocer el potencial de las TIC para el desarrollo de estrategias de aprendizaje relevantes de cara a mejorar el desempeno de las tareas academicas y el rendimiento. Llevamos a cabo para ello el estudio de la variable «Valoracion de las TIC para el desarrollo de estrategias de aprendizaje». Profundizamos en el analisis de esta variable estableciendo, a partir de los resultados del analisis factorial, dos tipos diferenciados de estrategias de aprendizaje (de pensamiento y procedimentales). El diseno incluye el analisis de las diferencias en las valoraciones de las TIC entre alumnos con distinto nivel de rendimiento academico. Como novedad incorporamos la representacion grafica de esas diferencias mediante las curvas ROC y el analisis de la similitud de resultados entre los valores AUC y los estadisticos no parametricos U y W. Entre las conclusiones destacar que los alumnos de mayor exito academico reconocen en las TIC un mayor potencial de apoyo en sus estrategias de aprendizaje. Las mayores diferencias entre alumnos (considerando las notas reales obtenidas), las podemos encontrar en la valoracion que hacen de las TIC para mejorar la elaboracion de trabajos, la organizacion de su actividad academica, las tareas de repaso, el trabajo con companeros y la busqueda de recursos.
Long Term Study of Peer Behavior in the kad DHT

Distributed hash tables (DHTs) have been actively studied in literature and many different proposals have been made on how to organize peers in a DHT. However, very few DHTs have been implemented in real systems and deployed on a large scale. One exception is KAD, a DHT based on Kademlia, which is part of eDonkey, a peer-to-peer file sharing system with several million simultaneous users. We have been crawling a representative subset of KAD every five minutes for six months and obtained information about geographical distribution of peers, session times, daily usage, and peer lifetime. We have found that session times are Weibull distributed and we show how this information can be exploited to make the publishing mechanism much more efficient. Peers are identified by the so-called KAD ID, which up to now was assumed to be persistent. However, we observed that a fraction of peers changes their KAD ID as frequently as once a session. This change of KAD IDs makes it difficult to characterize end-user behavior. For this reason we have been crawling the entire KAD network once a day for more than a year to track end-users with static IP addresses, which allows us to estimate end-user lifetime and the fraction of end-users changing their KAD ID.
Simultaneous Optimization of a Wheeled Mobile Robot Structure and a Control Parameter

A wheeled mobile mechanism with a passive and/or active linkage mechanism for traveling in the outdoor environment is developed and evaluated. In our previous research, we developed a wheeled mobile robot which has six wheels and a passive linkage mechanism, and its maneuverability was experimentally verified. The ability to climb over a 0.20 [m] high bump, which is twice height of the wheel diameter of 0.10 [m], was achieved, and the mobile robot can climb up continuous steps of 0.15 [m] high. In this research, we optimized the mobile robot linkage mechanisms and a controller parameter by evolutionary algorithm and dynamics engine in numerical simulations. The evolutionary algorithm employed in this research is Genetic Algorithm, and Open Dynamics Engine is used for dynamics calculation. To optimize the linkage mechanism and a controller parameter, we investigated outdoor environment for the mobile robot, for example obstacles, steps, and stairs. And, we selected typical three kinds of outdoor environments, 0.20 [m] high bump, right angle stairs of 0.15 [m] high, and angled stairs of 0.15 [m] high. In the numerical simulations, though the mobile robot using parameters which express our existing robot could climb up/down the 0.20 [m] high bump, but it could not achieve climbing up/down the two kinds of stairs. On the other hand, the optimized parameter mobile robot could climb up/down the three kinds of typical environments.
FAST ASYNCHRONOUS CONSENSUS BASED ON A WEAK FAILURE DETECTOR

The Consensus problem is a fundamental paradigm for fault-tolerant asynchronous systems. It abstracts a family of problems known as Agreement (or Coordination) problems. Any solution to consensus can serve as a basic building block to solve such problems (e.g., atomic commitment or atomic broadcast). Solving consensus in an asynchronous system is not a trivial task: it has been proven (1985) by Fischer, Lynch and Paterson that there is no deterministic solution in asynchronous systems that are subject to even a single crash failure. To circumvent this impossibility result, Chandra and Toueg have introduced the concept of unreliable failure detectors (1991), and have studied how these failure detectors can be used to solve consensus in asynchronous systems with crash failures. In this paper, we present a new consensus protocol that uses a failure detector of the class 3S. As previous protocols, our protocol is based on the rotating coordinator paradigm and proceeds in asynchronous rounds. Its design originality lies in (1) the use of a voting mechanism combined with a simple nite state automaton that manages the behavior of each process during each round, and in (2) the possibility for a process to change its mind during a round. This new protocol is more eecient than previous consensus protocols that use the same type of failure detectors. It is particularly eecient when, whether there are failures or not, the underlying failure detector makes few mistakes. Un protocole de consensus asynchrone rapide fond e sur un d etecteur de d efaillance faible R esum e : Le probl eme du Consensus est un paradigme essentiel dans le domaine des syst emes asynchrones tol erants aux d efaillances. Il abstrait une famille de probl emes connus sous le nom de probl emes d'accord (ou de coordination). Toute solution au probl eme du consensus peut servir de brique de base pour r esoudre de tels probl emes (en particulier le probl eme de la validation atomique et de la diiusion atomique). R esoudre le consensus dans un syst eme asynchrone est loin d'^ etre ais e: Il a et e prouv e (en 1985) par Fischer, Lynch et Paterson qu'il n'y a pas de solution d eterministe dans un syst eme asynchrone m^ eme lorsqu'un seul processus peut ^ etre d efaillant. Pour contourner ce r esultat d'impossibilit e, Chandra et Toueg ont introduit le concept de d etecteurs de d efaillance non ables …
Uniqueness and Completeness Analysis of Array Comprehensions Uniqueness and Completeness Analysis of Array Comprehensions 1

In this paper we introduce the uniqueness and completeness problems of array comprehensions. An array comprehension has the uniqueness property if it de nes each array element at most once. Uniqueness is a necessary condition for correctness in single assignment languages such as Haskell, Id, and Sisal. The uniqueness problem can be stated as a data dependence problem, which in itself can be reformulated as an integer linear programming problem. We derive algorithms to solve uniqueness using the Omega Test, an Integer Linear Programming tool. An array comprehension has the completeness property if all its elements are de ned. Completeness is a necessary condition for strict arrays. We present an algorithm that tests for completeness and describe an implementation of the algorithm based on multivariate polynomials.
Optimal cluster head selection schemes for hierarchical OFDMA based video sensor networks

In this paper we present a novel framework for cluster head (CH) selection and sub-carrier allocation towards intra-cluster communication in an Orthogonal Frequency Division Multiple Access (OFDMA) based Wireless Sensor Network (WSN). The proposed framework maximizes the overall performance of the WSN in terms of the throughput, video quality and network life. The OFDMA PHY optimization criterion for rate maximization is formulated as a bi-level optimization problem for CH node selection followed by optimal OFDMA sub-carrier allocation. It is then demonstrated that the above optimal resource allocation problem can be reduced to the solution of a weighted bipartite graph matching problem and is solved employing three different schemes, namely the popular Hungarian algorithm, game theory based multi-item auction and the Gale-Shapley stable matching scheme. Based on the above formulation, we also derive an optimal scheme to minimize the energy consumption in the WSN. Further, the performance of the proposed schemes is demonstrated through simulations in the context of scalable video transmission in a video sensor network. Results illustrate that these schemes significantly outperform suboptimal WSN cluster head selection schemes in terms of data rate and video quality.
Bayesian estimation for archaeological stratigraphyG

Models and algorithms are presented for the stratigraphic analysis of earth core samples collected at sites of archaeological interest, the aim being to separate the occupation of the site into distinct epochs, by dividing the earth core into well deened periods of uniform magnetic susceptibility. The models describe detector equipment response using both a point-spread function and a measurement error process, and incorporate appropriate prior beliefs regarding the nature of the true susceptibility values. The observed data likelihood and prior distribution are combined to produce a posterior distribution, on which estimation is based. The maximum a posteriori estimates are found numerically, using the OSL algorithm. These procedures are illustrated, and compared with maximum likelihood and the Fourier-based Wiener lter, using susceptibility data obtained from artiicial, phantom core specimens. The new procedures prove to be far superior to either of the other approaches, producing reconstructions which clearly show distinct periods of uniform magnetic susceptibility separated by sharp discontinuities.
Modeling and analysis of hierarchical cellular networks with general distributions of call and cell residence times

We present an analytic model for the performance evaluation of hierarchical cellular systems, which can provide multiple routes for calls through overflow from one cell layer to another. Our model allows the case where both the call time and the cell residence time are generally distributed. Based on the characterization of the call time by a hyper-Erlang distribution, the Laplace transform of channel occupancy time distribution for each call type (new call, handoff call, and overflow call) is derived as a function of the Laplace transform of cell residence time. In particular, overflow calls are modeled by using a renewal process. Performance measures are derived based on the product form solution of a loss system with capacity limitation. Numerical results show that the distribution type of call time and/or cell residence time has influence on the performance measure and that the exponential case may underestimate the system performance.
CC_SCR: A Compression Cluster-Based Scheme in a Spatial Correlated Region for Wireless Sensor Networks

In this paper, we propose a new Compression Cluster-based scheme in a Spatial Correlated Region (CC SCR) for event-driven applications in wireless sensor networks. The main idea behind our proposal is to exploit the spatial correlation of such networks in order to reduce the size of the data packets that will be sent by means of data compression. The proposed clustering scheme is based on selecting a data value as reference while the rest of the active nodes transmit only the difference between their sensed value and this reference value. Hence, one major issue in the proposed mechanism is to appropriate select the reference node that achieves the highest reduction of the packet size among all active nodes. The CC SCR protocol is evaluated by simulations. The results show that CC SCR may reduce as much as 11 times the energy consumption compared to a classical clustering scheme.
Facilitating self-directed learning (SDL) and satisfaction with SDL among pre-university students

Abstract The aim of the study was to evaluate our practice of self-directed learning (SDL) among pre-university students in Malaysia. Respondents provided data on their previous school learning experiences besides present SDL experiences in college. We carried out exploratory factor analysis based on the school data. We did a confirmatory factor analysis using College SDL experiences of students. Given high similarities between the measurement models, we decided to use the original structure of the instrument. Students provided feedback using a questionnaire based on Prociuk’s. A large majority declared that they needed SDL experiences which they lacked while at school. The study also showed that students had rated their SDL experiences in college more positively than in school, on four factors of SDL experiences. Pearson correlations showed that “knowledgeable and organised teachers” and “promotion of active learning” correlated significantly with students’ current satisfaction with SDL in college.
VLT Spectroscopy of GRB 990510 and GRB 990712: Probing the Faint and Bright Ends of the Gamma-Ray Burst Host Galaxy Population

We present time-resolved optical spectroscopy of the afterglows of the gamma-ray bursts GRB 990510 and GRB 990712. Through the identification of several absorption lines in the first-epoch GRB 990510 spectrum, we determine the redshift for this burst at z ≥ 1.619. No clear emission lines are detected. The strength of the Mg I feature is indicative of a dense environment, most likely the host galaxy of GRB 990510. Although the host is extremely faint (V ≳ 28), the GRB afterglow allows us to probe its interstellar medium and—in principle—to measure its metallicity. The optical spectrum of GRB 990712 (whose host galaxy is the brightest of the known GRB hosts at cosmological redshifts) shows clear features both in emission and absorption, at a redshift of z = 0.4331 ± 0.0004. On the basis of several line emission diagnostic diagrams, we conclude that the host galaxy of GRB 990712 is most likely an H II galaxy. We derive an unreddened [O II] star formation rate of 2.7 ± 0.8 M☉ yr-1. Correcting for the measured extinction intrinsic to the host galaxy (AV = 3.4), this value increases to 35 M☉ yr-1. The [O II] equivalent width, compared to that of field galaxies at z ≤ 1, also suggests that the host of GRB 990712 is vigorously forming stars. We employ the oxygen and Hβ emission-line intensities to estimate the global oxygen abundance for the host of GRB 990712: log(O/H) = -3.7 ± 0.4, which is slightly below the lowest metallicity one finds in nearby spiral galaxies. For both GRBs we study the time evolution of the absorption lines, whose equivalent width might be expected to change with time if the burst resides in a dense compact medium. We find no evidence for a significant change in the Mg II width.
Comprehensive simulations of superhumps

We use three-dimensional (3D) smoothed particle hydrodynamics (SPH) calculations with higher resolution, as well as with more realistic viscosity and sound-speed prescriptions than previous work to examine the eccentric instability which underlies the superhump phenomenon in semidetached binaries. We illustrate the importance of the two-armed spiral mode in the generation of superhumps. Differential motions in the fluid disc cause converging flows which lead to strong spiral shocks once each superhump cycle. The dissipation associated with these shocks powers the superhump. We compare two-dimensional (2D) and 3D results, and conclude that 3D simulations are necessary to faithfully simulate the disc dynamics. We ran our simulations for unprecedented durations, so that an eccentric equilibrium is established except at high mass ratios where the growth rate of the instability is very low. We collate the observed data on superhumps. Our improved simulations give a closer match to the observed relationship between superhump period excess and binary mass ratio than previous numerical work. The observed black hole X-ray transient superhumpers appear to have systematically lower disc precession rates than the cataclysmic variables. This could be due to higher disc temperatures and thicknesses. No high-resolution 3D disc with mass ratio q > 0.24 developed superhumps, in agreement with analytical expectations. The modulation in total viscous dissipation on the superhump period is overwhelmingly from the region of the disc within the 3:1 resonance radius R3:1. The precession rates of our high-resolution 3D discs match the single particle dynamical precession rate at 0.87 R3:1. As the eccentric instability develops, the viscous torques are enhanced, and the disc consequently adjusts to a new equilibrium state, as suggested in the thermal–tidal instability model. We quantify this enhancement in the viscosity, which is 10 per cent for q = 0.08. The disc motions can be described as superpositions of the S(k, l) modes, and the disc executes complex standing wave dynamics which repeat in the inertial frame on the disc precession period. We characterize the eccentricity distributions in our accretion discs, and show that the entire body of the disc partakes in the eccentricity.
Quantifying and Predicting Image Scenicness

Capturing the beauty of outdoor scenes in an image motivates many amateur and professional photographers and serves as the basis for many image sharing sites. While natural beauty is often considered a subjective property of images, in this paper, we take an objective approach and provide methods for quantifying and predicting the scenicness of an image. Using a dataset containing hundreds of thousands of outdoor images captured throughout Great Britain with crowdsourced ratings of natural beauty, we propose an approach to predict scenicness which explicitly accounts for the variance of human raters. We demonstrate that quantitative measures of scenicness can benefit semantic image understanding, content-aware image processing, and a novel application of cross-view mapping, where the sparsity of labeled ground-level images can be addressed by incorporating unlabeled aerial images in the training and prediction steps. For each application, our methods for scenicness prediction result in quantitative and qualitative improvements over baseline approaches.