Miracle-dz/UniFAR-FTUs huggingface dataset:
Ranking and new database architectures

Database platform support for efficient ranking can have positive performance implications for a number of rank-aware applications, including data exploration, social network analysis, and keyword search. This talk highlights two pieces of work where ranking appears in the research area of database architectures for new hardware. First, we highlight the Bw-tree, a new high-performance B+-tree supporting sorted key-sequential access. The Bw-tree is re-architected to run efficiently on new hardware: its in-memory operations are completely latch-free, removing blocking behavior while also improving multi-core cache behavior, while its storage layer implements a novel log-structured flash storage layer for that exploits fast sequential writes and mitigates adverse performance impact of random writes. Second, we highlight a new classification technique for identifying âĂIJcoldâĂİ (infrequently accessed) data in main-memory database systems. Using a log of sampled record accesses, our technique estimates record access frequencies using exponential smoothing. This classification approach is very efficient: it is able to accurately identify hot and cold records among 1M records in sub-second time from a log of 1B record accesses on a workstation class machine.
Exploring the Impact of an Appreciative Inquiry Framework: Nova Scotia IBDP Coordinators and Approaches to Teaching and Learning

The purpose of this paper is to present findings from a year-long study into the impact an appreciative inquiry framework had upon the professional learning of International Baccalaureate Diploma Programme (IBDP) Coordinators and Teachers located in urban and rural public high schools in Nova Scotia. Little research has been found that looks closely at the knowledge and experiences of International Baccalaureate (IB) coordinators and teachers as they engage in practices to sustain the Diploma Programme (DP). To do so, we invited participants from the 13 high schools offering the DP in order to determine the practices needed to foster optimum teaching and learning conditions. The design of the study drew upon multiple qualitative interviews with IB coordinators and teachers between June 2017 to June 2018, and as they participated in three professional learning workshops, based upon appreciative inquiry principles, over the 2017-2018 school year. Participants characterized their involvement in the appreciative inquiry workshops as being both reaffirming and clarifying. In this paper, we share how an appreciative inquiry approach had a reportedly positive impact upon participants’ professional learning and their desire to further enhance curricular and pedagogical initiatives informing their DPs.
Exploiting just-noticeable difference of delays for improving quality of experience in video conferencing

This paper proposes a novel approach for improving the quality of experience (QoE) of real-time video conferencing systems. In these systems, QoE is affected by signal quality as well as interactivity, both depending on the packet loss rate, delay jitters, and mouth-to-ear delay (MED) that measures the sender-receiver delay on audio signals (and will be the same as that of video signals when video and audio is synchronized). We notice in the current Internet that increasing MED as well as reducing packet rate can help reduce the delay-aware loss rate in congested connections. Between the two methods, the former plays a more important role and applies well to a variety of network conditions for improving audiovisual signal quality, although overly increasing the MED will degrade interactivity. Based on a psychophysical concept called just-noticeable difference (JND), we find the extent to which MED can be increased, without humans perceiving the difference from the original conversation. The approach can be applied to improve existing video conferencing systems. Starting from the operating point of an existing system, we increase its MED to within JND in order to have more room for smoothing network delay spikes as well as recovering lost packets, without incurring noticeable degradation in interactivity. We demonstrate the idea on Skype and Windows Live Messenger by designing a traffic interceptor to extend their buffering time and to perform packet scheduling/recovery. Our experimental results show significant improvements in QoE, with much better signal quality while maintaining similar interactivity.
Fringe analysis revisited

Fringe analysis is a technique used to study the average behavior of search trees. In this paper we survey the main results regarding this technique, and we improve a previous asymptotic theorem. At the same time, we present new developments and applications of the theory that allow improvements in several bounds on the behavior of search trees. Our examples cover binary search trees, AVL-trees, 2–3 trees, and B-trees.
Gender role portrayals in television advertisements: Do channel characteristics matter?

Abstract In the present study we investigated the role of channel characteristics with regard to gender role portrayals in television advertisements. Drawing on cultivation theory and social cognitive theory, we investigated six key variables in this line of research. We sampled a total of N = 1022 advertisements from four Austrian television channels: a public service channel, a commercial channel, and one commercial special interest channel for men and for women, respectively. Our results replicate well-known stereotypic gender role portrayals prevalent in television advertisements. The public service channel and the private channel did not differentiate from each other with regards to gender stereotyping. We found that a channel with a female target group aired advertisements containing the same or even amplified stereotypes compared to a male channel. The potential negative effects of stereotypic gender role portrayals in television advertisements are discussed.
Urban Vegetation Mapping from Fused Hyperspectral Image and LiDAR Data with Application to Monitor Urban Tree Heights

Urban vegetations have infinite proven benefits for urban inhabitants including providing shade, improving air quality, and enhancing the look and feel of communities. But creating a complete inventory is a time consuming and resource intensive process. The extraction of urban vegetation is a challenging task, especially to monitor the urban tree heights. In this study we present an efficient extraction method for mapping and monitoring urban tree heights using fused hyperspectral image and LiDAR data. Endmember distribution mapping using the spectral angle mapper technique is employed in this study. High convenience results achieved using fused hyperspectral and LiDAR data from this semiautomatics technique. This method could enable urban community organizations or local governments to map and monitor urban’s tree height and its spatial distribution.
Decrepol: A Decentralized Replication Policy for Web Documents

The current size of the Internet makes it impossible to host major Web sites on a single server. Replication can improve both the availability and the performance of a Web hosting service. Current replication policies heavily rely on the origin server. Therefore, this thesis presents Decrepol, a decentralized replication policy for Web documents that assumes the origin server to be unavailable most of the time. First, we present a replication policy that achieves full replication and is structured following epidemic protocols. With this policy we are able to spread notifications across 128 replica servers in about 5 gossip rounds. Next, we present a decentralized replication policy that allows for controlled partial replication. We create two versions of the partial replication policy. The first one is based on epidemic protocols and is an extented version of the full replication policy. However, in this policy locating replicas becomes a problem. Therefore, we also present an improved unstructured version that facilitates locating content. With this version, inserting and retrieving documents requires traversing about three hops. The second version is based on structured peer-to-peer systems. Inserts take about four hops, retrieves only two hops if we cache document searches. We show that it is possible to create an unstructured partial replication policy that performs almost identically to a structured one and thus can be an interesting alternative.
Retirement Decisions of Couples: The Impact of Spousal Characteristics and Preferences on the Timing of Retirement

This paper provides new evidence of coordination of retirement by mature age couples in Australia. Two complementary estimation approaches are used to highlight the importance of taking the household decision-making context into account when modeling the retirement behaviour of partnered men and women. First, a single risk hazard model provides insights into the influences of a spouse’s characteristics on the retirement decision of the individual. Second, a competing-risks framework is used to examine the retirement behaviour of couples exiting from a situation in which both are in paid employment. There is strong evidence of coordination of retirement by mature age couples in Australia due to complementarities in leisure and, for women, because of caring responsibilities. In particular, the results suggest that women may delay their own retirement if their partner has a financial incentive to continue in the labour force; or retire early to care for a partner who is in poor health.
Improved algorithms for linear inequalities with two variables per inequality

We show that a system of m linear inequalities wit h n variables, where each inequality involves at most two variables, can be solved det erministically in O(mn log m + mnz log2 n) time. A randomized O(n3 log n + mn log3 n log m + mn log5 n) time algorithm is given for the case where in every inequality the two nonzero coefficients have opposite signs (monotone systems). This algorithm improves the known time bounds for the incapacitated generalized transshipment problem, with many sources and no sinks. We also present a new algorithm that solves the capacitated generalized flow problem by iteratively solving monotone systems. Combined with the improved bound, it yields the fastest known algorithm for the problem which does not rely on the theoretically fast matrix multiplication algorithms. This approach also yields the first strongly polynomial time bound for approximating the maximum generalized flow within any constant factor.
Efficient Computation of Polynomial Explanations of Why-Not Questions

Answering a Why-Not question consists in explaining why a query result does not contain some expected data, called missing answers. This paper focuses on processing Why-Not questions in a query-based approach that identifies the culprit query components. Our first contribution is a general definition of a Why-Not explanation by means of a polynomial. Intuitively, the polynomial provides all possible explanations to explore in order to recover the missing answers, together with an estimation of the number of recoverable answers. Moreover, this formalism allows us to represent Why-Not explanations in a unified way for extended relational models with probabilistic or bag semantics. We further present an algorithm to efficiently compute the polynomial for a given Why-Not question. An experimental evaluation demonstrates the practicality of the solution both in terms of efficiency and explanation quality, compared to existing algorithms.
ROBUST VOICED / UNVOICED CLASSIFICATION USING NOVEL FEATURES AND GAUSSIAN MIXTURE MODEL

Need for deciding whether a given frame of a speech waveform should be classified as voiced speech or unvoiced speech arises in many speech analysis systems. Several approaches have been described in the literature for making this decision. In this paper, we have presented two novel approaches of using acoustical features and pattern recognition. The first method is based on Mel frequency cepstral coefficient with Gaussian mixture model classifier, which resulted in approximately 90% identification accuracy and the other is based on LPC coefficient and reduced dimensional LPC residual with Gaussian mixture model classifier, which resulted in 92% identification accuracy. The performances of both approaches were compared for various levels of noise and optimum condition for training is determined.
Factors contributing to faculty satisfaction and its relationship to faculty retention in tertiary religious institutions

This study aimed to identify factors contributing to faculty satisfaction and their relationship to faculty retention. The research design was a cross-sectional survey. Furthermore, it looked at correlative relations by using factor analysis and ANOVA. Purposive sampling was used to identify a total of 185 respondents from 4 religious universities in Manado, Indonesia. The sample responded to a 2-part questionnaire. Results showed that faculty satisfaction affected faculty retention F (2, 177) = 3. 05, p = . 05, significantly and positively. However, institutional value (M = 4.27, SD = .66), which was one of the 3 satisfaction factors, affected faculty retention more than the other two factors, which were institutional support (M = 3.90, SD = .68) and working conditions (M = 3.94, SD = .68). For faculty members to be highly satisfied and remain in service, administrators should provide support in terms of working conditions, institutional value, and institutional support.
The dynamics study of the stick-slip driving system based on LuGre dynamic friction model

In this paper, a dynamics model of stick-slip driving system based on LuGre friction model was proposed. In the building of dynamics model of stick-slip driving system, a novel structure of stick-slip stage was designed and LuGre friction model was selected which is most suitable for the stick-slip driving. Combined with LuGre model and dynamics model of flexible hinge, the dynamics model of stick-slip system was built and simulated in Simulink software. The displacement, speed and acceleration curve of PZT, inertial mass and slider were obtained. Experiment prototype and the testing of stick-slip driving system were also designed. The actual displacement curve of different direction of slider and the step displacement curve of PZT were tested and the problem of different direction with different displacement was found. In order to better compare testing results and simulation results, simulation results and testing results were processed to show in a figure. The simulation results are validated by the testing results. Therefore, the dynamics model is suitable to study the novel stick-slip stage and a kind of problem in stick-slip driving.
Essays in mathematical finance : modeling the futures price

This thesis consists of four papers dealing with the futures price process. In the first paper, we propose a two-factor futures volatility model designed for the US natural gas market, but applicable to any futures market where volatility decreases with maturity and varies with the seasons. A closed form analytical expression for European call options is derived within the model and used to calibrate the model to implied market volatilities. The result is used to price swaptions and calendar spread options on the futures curve. In the second paper, a financial market is specified where the underlying asset is driven by a d-dimensional Wiener process and an M dimensional Markov process. On this market, we provide necessary and, in the time homogenous case, sufficient conditions for the futures price to possess a semi-affine term structure. Next, the case when the Markov process is unobservable is considered. We show that the pricing problem in this setting can be viewed as a filtering problem, and we present explicit solutions for futures. Finally, we present explicit solutions for options on futures both in the observable and unobservable case. The third paper is an empirical study of the SABR model, one of the latest contributions to the field of stochastic volatility models. By Monte Carlo simulation we test the accuracy of the approximation the model relies on, and we investigate the stability of the parameters involved. Further, the model is calibrated to market implied volatility, and its dynamic performance is tested. In the fourth paper, co-authored with Tomas Bjork and Camilla Landen, we consider HJM type models for the term structure of futures prices, where the volatility is allowed to be an arbitrary smooth functional of the present futures price curve. Using a Lie algebraic approach we investigate when the infinite dimensional futures price process can be realized by a finite dimensional Markovian state space model, and we give general necessary and sufficient conditions, in terms of the volatility structure, for the existence of a finite dimensional realization. We study a number of concrete applications including the model developed in the first paper of this thesis. In particular, we provide necessary and sufficient conditions for when the induced spot price is a Markov process. We prove that the only HJM type futures price models with spot price dependent volatility structures, generically possessing a spot price realization, are the affine ones. These models are thus the only generic spot price models from a futures price term structure point of view.
Trade-Off between Spectrum Efficiency and Link Unavailability for Hierarchical Modulation in DVB-S2 Systems

Broadcasting systems have to deal with channel variability in order to offer the best spectrum efficiency to the receivers. However, the transmission parameters that optimize the spectrum efficiency generally leads to a large link unavailability. In this paper, we study the performance of hierarchical and non-hierarchical modulations in terms of spectrum efficiency and link unavailability for DVB-S2 systems. Our first contribution is the design of the hierarchical 16-APSK for the DVB-S2 standard. Then we introduce the link unavailability to compare the performance of hierarchical and non-hierarchical modulations in terms of spectrum efficiency and link unavailability. The results show that hierarchical modulation is a good alternative to non-hierarchical modulation for the DVB-S2 standard.
OPTIMAL INTRA-CODED VIDEO SUMMARIZATION FOR TWO BANDWIDTH LIMITED CHANNELS

For video communication over a wireless ad hoc network, multiple paths with different rates are common. This paper considers the transmission of intra-coded video sequences through two bandwidth limited channels. More specifically, with the proposed framework a rate-distortion optimal summary of the video sequence is generated first, utilizing the cumulative bit rate of the two channels. In a second step the frames of the summary are distributed between the two channels according to the individual channel rates. Toward this task, a greedy suboptimal distribution algorithm and an optimal distribution algorithm, based on the knapsack theory, are shown. Experimental results are presented.
E-learning: emerging issues and key trends: a discussion paper

The purpose of this short paper is to provide a view of the state of e-learning, issues and implications for the use of technology mediated and delivered instruction in the vocational education and training (VET) sector in particular. The paper was developed in a short time frame to inform the planning cycle for initiatives within the Australian Flexible Learning Framework in June 2003. It aims to integrate a review of literature to provide a high level comparative view of the current and future directions for e-learning, and possible implications for policy and practice. The paper does not seek to inform on a technical level and it assumes knowledge of terminology and issues in using technologies in teaching and learning. The authors comment on current and possible events in other sectors that may influence the shape of e-learning in VET. The paper considers issues and developments of a technical, organisational and pedagogical nature that are likely to generate change in the use of technologies in education and training. The paper offers a view of the driving forces for e-learning, an historical context for its development, and a vision for the future with recommendations for the Framework.
A role-based conflict resolution method for a collaborative system

Conflict resolution is one of the most important problems that must be solved in building a collaborative system. In many CSCW (computer-supported-cooperative work) applications or systems, roles were granted in the design and application of these systems. Consequently, we may infer that "without roles, there would be no collaboration". Based on the success of RBAC, we found that role-based methods are very useful in building collaborative systems. However, there is little research on conflict resolution based on roles. This paper, briefly introduces an object model for collaborative systems OMCS and a multimedia co-authoring system MCAS, and mainly discusses the role management and a role-based conflict avoidance and resolution method in the system MCAS. It emphasizes the importance of roles in conflict avoidance and resolution. In the last section, it summarizes the paper and draws a conclusion is drawn that a role-based method can help greatly to resolve conflicts in collaborative systems.
A study of the behavior of TCP in variable-bandwidth environments

Most of the studies on TCP have assumed than the bottleneck bandwidth remains constant over time. In wired networks, the available bandwidth for best-effort traffic is usually constant but major changes are foreseen as many telco operators and Internet providers (ISP) are beginning to deploy Quality of Service (QoS) features with reservationlike or priority-like mechanisms in their networks. These new technologies, along with the strong desire to provide bandwidth-on-demand features, may turn wired networks into highly variable-bandwidth environments (VBE) for the best-effort traffic. In this paper we present a preliminary study of TCP in VBE and show simulation results to better understand the behavior and the performances of TCP in such environments. Both sine-based and step-based bandwidth variations models are used.
Emotion Oriented Programming: Computational Abstractions for AI Problem Solving

In this paper, we present a programming paradigm for AI problem solving based on computational concepts drawn from Affective Computing. It is believed that emotions participate in human adaptability and reactivity, in behaviour selection and in complex and dynamic environments. We propose to define a mechanism inspired from this observation for general AI problem solving. To this purpose, we synthesize emotions as programming abstractions that represent the perception of the environment's state w.r. t. predefined heuristics such as goal distance, action capability, etc. We first describe the general architecture of this "emotion-oriented" programming model. We define the vocabulary that allows programmers to describe the problem to be solved (i.e. the environment), and the action selection function based on emotion abstractions (i.e. the agent's behaviours). We then present the runtime algorithm that builds emotions out of the environment, stores them in the agent's memory, and selects behaviours accordingly. We present the implementation of a classical labyrinth problem solver in this model. We show that the solutions obtained by this easy-to-implement emotion-oriented program are of good quality while having a reduced computational cost.