An Analysis Of The Saftey Effects Of Crosswalks With In-pavement Warning Lights

Pedestrian safety is among one of the largest concerns in the transportation profession. Many treatments have been developed and implemented to improve pedestrian safety. This current research focuses on the efficiency of in-pavement warning lights systems and involves multiple objectives. The primary objective is to evaluate the yielding rates and crosswalk usage of existing and proposed in-pavement lights systems with comparisons including before and after data through a case study approach. A secondary objective is to evaluate where drivers are looking when they approach in-pavement lights systems and develop a model to evaluate their behavior. The research described herein formulated these objectives into two research hypotheses and used statistical evaluation methodologies to provide quantitative and/or qualitative responses to the developed hypotheses. Data on pedestrian and driver behavior in the field, and the interaction between, them was collected using video camera technology in the Amherst, Massachusetts area. Data regarding drivers scan patterns during the approach to a crosswalk with in-pavement warning light system was collected using a driving simulator and an eye tracker. In total, 1,949 non-staged pedestrians and 606 staged pedestrians were observed crossing at the seven crosswalk locations in the field experiment and a total of 32 drivers participated in 576 crosswalk scenarios in the driving simulator evaluation. The field evaluation resulted in increased yielding rates and crosswalk usage after installation of in-pavement warning lights, while driving simulator evaluation resulted in drivers not becoming accustomed to scanning for lights instead of a pedestrian. Recommendations include installation of in-pavement warning lights at traditional, midblock crosswalks and continued exploration of all crosswalks in the driving simulator evaluation

Optimal prefix codes for pairs of geometrically-distributed random variables

Optimal prefix codes are studied for pairs of independent, integer-valued symbols emitted by a source with a geometric probability distribution of parameter $q$, $0{<}q{<}1$. By encoding pairs of symbols, it is possible to reduce the redundancy penalty of symbol-by-symbol encoding, while preserving the simplicity of the encoding and decoding procedures typical of Golomb codes and their variants. It is shown that optimal codes for these so-called two-dimensional geometric distributions are \emph{singular}, in the sense that a prefix code that is optimal for one value of the parameter $q$ cannot be optimal for any other value of $q$. This is in sharp contrast to the one-dimensional case, where codes are optimal for positive-length intervals of the parameter $q$. Thus, in the two-dimensional case, it is infeasible to give a compact characterization of optimal codes for all values of the parameter $q$, as was done in the one-dimensional case. Instead, optimal codes are characterized for a discrete sequence of values of $q$ that provide good coverage of the unit interval. Specifically, optimal prefix codes are described for $q=2^{-1/k}$ ($k\ge 1$), covering the range $q\ge 1/2$, and $q=2^{-k}$ ($k>1$), covering the range $q<1/2$. The described codes produce the expected reduction in redundancy with respect to the one-dimensional case, while maintaining low complexity coding operations.Comment: To appear in IEEE Transactions on Information Theor

Perfil del tutor una estrategia en matemáticas para abatir reprobación y deserción en bachillerato

Los alumnos que ingresan al bachillerato carecen de los conocimientos matemáticos mínimos para adaptarse al nuevo régimen de estudio que exige la Educación Media Superior. El presente trabajo de investigación se centra en la implementación de un “Proyecto Institucional de Tutorías” en el campo de las matemáticas, focalizando en el perfil del tutor como una estrategia de intervención en el proceso de aprendizaje de los alumnos sin demeritar todos los esfuerzos que el entorno del estudiante pueda proporcionarle; la acción tutorial constituye el seguimiento tanto individual como grupal en el proceso de formación integral de los alumnos, fomentando la mejora de las estrategias dirigidas a estimular el crecimiento de habilidades y destrezas de los estudiantes con el único objetivo de alcanzar la eficiencia y eficacia para mejorar el nivel académico

The Implementation of Research Findings for LIS Professional Practices in Selected Academic Libraries in Sub-Saharan Africa

Implementing research findings influences professional growth, provides evidence, and improves practice. Time and money go to waste if research findings are not adequately used. This study was set to understand how LIS Masters and PhDs research findings influence professional practices in academic libraries. The qualitative study used an online semi-structured interview to collect data from twelve (12) selected academic libraries in the Sub Sahara, Africa. Data was analysed thematically. The participants of this study attest that research findings from Master’s and PhD students are integrated into activities and provide evidence for decision-making. However, no precise mechanism supported the implementation of the findings. Funding, lack of awareness, and resistance to change hindered the implementation of the research. There is no clear link between the researchers and the academic libraries. Academic libraries studied, tracked, and preserved the research using institutional repositories, though they neither have a clear research agenda nor are aware of their parent institutions’ research agenda. The study recommends that academic libraries, to implement research findings effectively, can follow an eight-step-by-step procedure of best principles of implementation science, advocate, and collaborate with partners to secure funds for research. Though researchers have the freedom to decide the research problem, academic libraries should have a voice in some of the research to ease the implementation of the findings. Library schools should include the implementation of research findings or evidence-based practice as part of the research chain to spur innovation and creativity in LIS

Blind Algorithm Development for Peak to Average Power Ratio Reduction in OFDM Systems under Frequency Selective Channels

One major drawback of orthogonal frequency division multiplexing (OFDM) system is peak to average power ratio (PAPR). This effect causes high power amplifier (HPA) to introduce intermodulation and out of band radiation as the signal goes through, thus degrades the performance of OFDM systems. This paper proposes blind algorithms which takes advantage of signal transformation technique and signal distortion technique. Simulation results show that at complementary cumulative distribution function (CCDF) level of 10-3 , the proposed algorithm achieved 3.2 dB PAPR improvement compared to discrete Fourier transform with interleaved frequency division multiple access (DFT-IFDMA) based algorithm. The bit error rate (BER) performance has degraded by 2 dB compared to the original OFDM signal with no distortion under frequency selective channel (FCS) at BER of 10-4 . These presented results, mark this algorithm as a better candidate for PAPR reduction algorithm in long term evolution (LTE) network. Under AWGN channels, the proposed algorithm performs better both in low and high signal power values. Under frequency selective channels, the existing and proposed algorithm converges after 10 dB of signal to noise power values. The low BER transmissions at low signal power values signify energy efficiency, ideal for portable wireless devices with limited battery power