Simulation and optimization of tool-life in manufacturing centers

This paper presents the development of an optimization and a computer-simulation model to evaluate the process plans of a manufacturing center by analyzing the effect of tool failure on system performance. The GPSS/PC simulation program that is used in this study has been built with variables, functions and matrices so that many experiments could be conducted with the model. Sensitivity analysis is presented and the developed model has proven to be useful in determining optimum sequencing of parts for various operating policies.     

Effects of Luminous Environment on Worker Productivity in Building Spaces

This paper is based in part, on the results of a survey undertaken by the writer for an industrial client. The purpose was to collect and systematize information on quantitative relations between the indoor environment and worker productivity. Office workers strongly believe that lighting conditions are an extremely important aspect of their workspace environment. Unfavorable conditions may hamper productivity. Daylighting is of particular importance. It is further shown that lighting conditions have a strong impact on worker performance in industrial facilities. Certain lighting strategies can contribute to an enhancement in worker productivity while cutting down on energy consumption. The influence on worker productivity of different characteristics of illumination are described. These include spectral distribution, color rendition, glare, daylight versus artificial light, and others. The presence or absence of windows on worker comfort and perception is also discussed. It is shown that improving lighting conditions is a highly cost-effective method of increasing worker productivity in office spaces as well as in manufacturing facilities.     

A large vocabulary system for Arabic online handwriting recognition

The success of using Hidden Markov Models (HMMs) for speech recognition application has motivated the adoption of these models for handwriting recognition especially the online handwriting that has large similarity with the speech signal as a sequential process. Some languages such as Arabic, Farsi and Urdo include large number of delayed strokes that are written above or below most letters and usually written delayed in time. These delayed strokes represent a modeling challenge for the conventional left-right HMM that is commonly used for Automatic Speech Recognition (ASR) systems. In this paper, we introduce a new approach for handling delayed strokes in Arabic online handwriting recognition using HMMs. We also show that several modeling approaches such as context based tri-grapheme models, speaker adaptive training and discriminative training that are currently used in most state-of-the-art ASR systems can provide similar performance improvement for Hand Writing Recognition (HWR) systems. Finally, we show that using a multi-pass decoder that use the computationally less expensive models in the early passes can provide an Arabic large vocabulary HWR system with practical decoding time. We evaluated the performance of our proposed Arabic HWR system using two databases of small and large lexicons. For the small lexicon data set, our system achieved competing results compared to the best reported state-of-the-art Arabic HWR systems. For the large lexicon, our system achieved promising results (accuracy and time) for a vocabulary size of 64k words with the possibility of adapting the models for specific writers to get even better results.     

Statewide investigation of the role of pyrethroid pesticides in sediment toxicity in California's urban waterways

A statewide investigation of urban creek sediment toxicity was conducted in California in recognition of increased incidences of toxicity linked to pyrethroid pesticides. The goals were to examine the spatial occurrence and magnitude of sediment toxicity in California urban creeks, and to examine the role of pyrethroids in toxic urban creek sediment samples. After a preliminary screening of 90 sites, 30 creeks were sampled in eight geographical regions. Sediment toxicity was assessed using 10 day bioassays with the resident amphipod Hyalella azteca. Bioassays were conducted at two test temperatures of 23 degrees C and at 15 degrees C to provide evidence of the cause of toxicity, and to more accurately reflect ambient environmental temperatures. Twenty-five of 30 samples were toxic when tested at 23 degrees C, and all 30 samples were toxic when tested at 15 degrees C. The magnitude of toxicity increased in samples tested at 15 degrees C suggesting the influence of pyrethroids, which are more toxic at colder temperatures. Pyrethroids were present in all sediment samples and were the only compounds detected at concentrations toxic to H. azteca. Bifenthrin was the pyrethroid of greatest toxicological concern, occurring in all 30 samples at concentrations up to 219 ng/g. Pyrethroid contamination of urban creeks was most severe in the Los Angeles, Central Valley, and San Diego regions, respectively. However, pyrethroids were also linked to urban creek aquatic toxicity in all regions sampled, including the less urbanized areas of the North Coast and Lake Tahoe.     

Synchronization-Sensitive Frame Estimation: Video Quality Enhancement

Network transmission is liable to errors and data loss. In movie transmission, packets of video frames are subject to loss or even explicit elimination for many reasons including congestion handling and the achievement of higher compression. Not only does the loss of video frames cause significant reduction in video quality, but it could also cause a loss of synchronization between the audio and video streams. If not corrected, this cumulative loss can seriously degrade the motion picture's quality beyond viewers' tolerance. In this paper, we study and classify the effect of audio-video de-synchronization. Afterwards, we develop and examine the performance and appropriateness of the application of many client-based techniques in the estimation of lost frames using the existing received frames, without the need for retransmissions or error control information. The estimated frames are injected at their appropriate locations in the movie stream to restore the loss. The objective is to enhance video quality by finding a very close estimate to the original frames at a suitable computation cost, and to contribute to the restoration of synchronization within the tolerance level of viewers.     

Hiding iris data for authentication of digital images using wavelet theory

This paper introduces an efficient approach to protect the ownership by hiding an iris data into digital image for an authentication purpose. It is based on the theory of wavelets. The idea is to secretly embed biometric data (iris print) in the content of the image identifying the owner. The system is based on an empirical analysis of biometric and watermarking technologies, and it is split into several processes. The first process is based on iris image analysis, which aids the generation of the iris code (watermark); the second and the third processes deal with embedding and detecting a watermark; and the last process deals with the authentication. A new metric that measures the objective quality of the image based on the detected watermark bit is introduced, which does not require the original unmarked image for watermark detection. Simulation results show the effectiveness and efficiency of the proposed approach. The text was submitted by the author in English.     

A novel facile synthesis and characterization of molybdenum nanowires

We describe a straightforward technique to synthesize pure Mo nanowires (NWs) from Mo₆S_yI_z (8,2 <y + z ≤ 10) NWs as precursor templates. The structural transformations occur when Mo₆S_yI_z NWs are annealed in Ar/H₂ mixture leading to the formation of pure Mo NWs with similar structures as initial morphologies. Detailed microscopic characterizations show that large diameters (>15 nm) Mo NWs are highly porous, while small diameters (<7 nm) are made of solid nanocrystalline grains. We find NW of diameter 4 nm can carry up to 30 μA current without suffering structural degradation. Moreover, NWs can be elastically deformed over several cycles without signs of plastic deformation.     

New syntheses of pyrazolo[3,4-d]pyrimidine,pyrazolo[3,4-d]pyridazine,isoindolinedione and pyrazole derivatives

Phenacylmalononitriles 2 react with hydrazines, acetic-hydrochloric acid and with diazotised primary aromatic amines to afford phenacylpyrazole ( 5a,b ), aminofurans ( 6a,b ) and aminopyrazole derivatives ( 3a,d ) respectively. The synthesised derivatives ( 3d, 6a ) were the key materials for the synthesis of isoindolinedione, ( 7a – c ) pyrazolopyrimidine ( 9, 10 ), and pyrazolopyridazine derivatives ( 11 ). The structures of the newly synthesised heterocycles were established on the basis of elemental analyses and spectral data besides synthesis via other routes.     

On comparison of luminescence properties of La2Zr2O7 and La2Hf2O7 nanoparticles

Unveiling the underlying mechanisms of properties of functional materials, including the luminescence differences among similar pyrochlores A₂B₂O₇, opens new gateways to select proper hosts for various optoelectronic applications by scientists and engineers. For example, although La₂Zr₂O₇ (LZO) and La₂Hf₂O₇ (LHO) pyrochlores have similar chemical compositional and crystallographic structural features, they demonstrate different luminescence properties both before and after doped with Eu³⁺ ions. Based on our earlier work, LHO-based nanophosphors display higher photo- and radioluminescence intensity, higher quantum efficiency, and longer excited state lifetime compared to LZO-based nanophosphors. Moreover, under electronic O²⁻→Zr⁴⁺/Hf⁴⁺ transition excitation at 306 nm, undoped LHO nanoparticles (NPs) have only violet blue emission, whereas LZO NPs show violet blue and red emissions. In this study, we have combined experimental and density functional theory (DFT) based theoretical calculation to explain the observed results. First, we calculated the density of state (DOS) based on DFT and studied the energetics of ionized oxygen vacancies in the band gaps of LZO and LHO theoretically, which explain their underlying luminescence difference. For Eu³⁺-doped NPs, we performed emission intensity and lifetime calculations and found that the LHOE NPs have higher host to dopant energy transfer efficiency than the LZOE NPs (59.3% vs 24.6%), which accounts for the optical performance superiority of the former over the latter. Moreover, by corroborating our experimental data with the DFT calculations, we suggest that the Eu³⁺ doping states in LHO present at exact energy position (both in majority and minority spin components) where oxygen defect states are located unlike those in LZO. Lastly, both the NPs show negligible photobleaching highlighting their potential for bioimaging applications. This current report provides a deeper understanding of the advantages of LHO over LZO as an advanced host for phosphors, scintillators, and fluoroimmunoassays.     

Tuning the Properties of CZTS Films by Controlling the Process Parameters in Cost-Effective Non-vacuum Technique

Highly dispersive Cu₂ZnSnS₄ (CZTS) nanoparticles were successfully synthesized by a simple solvothermal route. A low cost, non-vacuum method was used to deposit CZTS nanoparticle ink on glass substrates by a doctor blade process followed by selenization in a tube furnace to form Cu₂ZnSn (S,Se)₄ (CZTSSe) layers. Different selenization conditions and particle concentrations were considered in order to improve the crystallinity and surface morphology; the annealing temperature was varied between 400°C and 550°C and the annealing time was varied between 5 min and 20 min in a selenium-nitrogen atmosphere. The influence of annealing conditions on structural, compositional, optical and electrical properties of CZTSSe thin films was studied. An improvement in the structural and surface morphology was observed with increasing of annealing temperature (up to 500°C). An enhancement in the crystallinity and surface morphology were observed for thin films annealed for 10–15 min. Absorption study revealed that the band gap energy of as-deposited CZTS thin film was approximately 1.43 eV, while for CZTSSe thin films it ranged from 1.15 eV to 1.34 eV at different annealing temperatures, and from 1.33 eV to 1.38 eV for different annealing times.