An improved SPIHT algorithm for lossless image coding

In this paper, we propose a new wavelet-based lossless image coder that is based on a state-of-the-art algorithm, namely SPIHT (set partitioning in hierarchical trees). An algorithmic modification is introduced in order to increase its efficiency. This consists of adding a new test on direct descendants in the sets of type A to process the parent coefficients that are significant due to their nondirect descendants. Also, new sets of type C are defined to perform a separate sorting of the sets that have insignificant children. The idea behind the second proposition is to remove all tests over the entries (A, B and C) since the number of significant sets is much higher than that of insignificant sets. A number of experiments, carried out on various test images, demonstrates significant improvement over the conventional SPIHT for both greyscale and colour images.     

Low-temperature processing and characterization of single-phase PZT powders by sol-gel method

A new sol-gel system using acetoin was developed and employed for the fabrication of PZT powders and films with compositions near the morphotropic phase boundary Pb(Zr_0.52Ti_0.48)O₃. Acetoin was used as chelating agent to replace the highly toxic methoxyethanol used in previous formulations. This route simplified the chemical processing of PZT-based solutions. Powders were completely crystallized by about 450 °C and contained the ferroelectric perovskite single phase. The firing temperature and time were to be the most important variables. Metallic lead formed only when excess Pb was incorporated. The precursor and the heat-treated powders have been characterized by using thermal analysis and X-ray diffractometry (XRD) studies. The average particle size, as measured from X-ray line broadening, was ∼35 nm.     

Effect of load,processing time and due date variation on the effectiveness of scheduling rules

In real manufacturing environments, variations in production factors (i.e. processing time, demand, due-dates) are inevitable facts. All these dynamic changes, together with random disturbances (e.g. machine breakdowns) can seriously affect the system performance. In this paper we focus on load, processing time and due date variation and analyse their impacts on a scheduling system. Specifically, we investigate the impact of variation on dispatching policies in a job shop environment via simulation. The statistical analysis of the results leads to two major conclusions: first, the relative performance of rules is not threatened much by PV (processing time variation), LV (load variation) or DDV (due date variation) -- a result that can be a consolation for practitioners in the field. Secondly, the performance of the rules deteriorates, in particular at high levels of PV, LV and DDV -- a result that can provide new insights into the problem and produces useful information for researchers in their continuous effort to develop better dispatching rules.     

Effect of biobased plasticizers on thermal,mechanical, and permanence properties of poly(vinyl chloride)

Phthalates can be replaced by other harmless and environmentally friendly plasticizers, such as isosorbide diesters (ISB), and epoxidized sunflower oil (ESO), which has been proved an efficient stabilizer for poly (vinyl chloride) (PVC) in helping to prevent degradation during processing. Formulations based on PVC with different amounts of ISB, ESO, and di‐(2‐ethylhexyl) phthalate (DEHP) from 0 to 60 parts by weight per hundred parts of resin were realized. To make PVC flexible with partial amounts of the debated phthalates as plasticizers, we use a combination of DEHP, ISB, and ESO. Effects of these two biobased plasticizers, ISB and ESO, and their mixture with DEHP on thermal stability by measuring discoloration degrees and thermal gravimetric analysis, on mechanical properties such tensile strength, elongation at break, and hardness, were characterized. Plasticizer permanence properties of PVC compounds were studied. Studies showed that processibility and flexibility were improved by the addition of a plasticizer system (ISB, ESO, and DEHP). An increase in the content of ISB and/or ESO increased thermal and mechanical properties, whereas compositions with ternary compositions of ISB/ESO/DEHP (15/15/30) exhibited the best performance properties. J. VINYL ADDIT. TECHNOL., 20:260–267, 2014. © 2014 Society of Plastics Engineers     

HYDRODYNAMIC AND ELASTOHYDRODYNAMIC STUDIES OF A CYLINDRICAL JOURNAL BEARING

In this article, the effect of the bearing elastic deformation on the performance characteristics of a cylindrical journal bearing is analyzed. The variety of simulation models covers hydrodynamic (HD) and elastohydrodynamic (EHD) lubrication theories. The Reynolds equations governing the flow in the clearance space of the journal bearing are obtained by considering the effect of mass transfer across the fluid film. The finite element method with an iteration scheme was employed to solve both the Reynolds equation and the three-dimensional elasticity equation representing the displacement field in the bearing shell. The converged solutions for the lubricant flow and elastic deformation vector are obtained. Dynamic characteristics of the journal bearing are computed for HD and EHD theories. Numerical simulation results show that the flexibility of bearing liner has a significant influence on the performance of a cylindrical journal bearing. Indeed, the elastic deformations of the bearing liner extend the pressure area in the bearing and increase the minimum film thickness. Although, dynamic coefficient, load capacity and attitude angle decrease.     

ACOUSTIC ANALYSIS OF HYDRODYNAMIC AND ELASTO-HYDRODYNAMIC OIL LUBRICATED JOURNAL BEARINGS

The purpose of the present paper is to investigate the effect of elastic deformation of bearing liner on the acoustic behavior of oil lubricated journal bearings.Analysis is performed for hydrodynamic(HD) and elasto-hydrodynamic (EHD) lubrications.Dynamic behavior and acoustical properties are investigated through an analysis of pressure fluctuation calculated from the Reynolds equation governing the flow in the clearance space of the journal bearing.This is solved numerically using the finite difference method with the successive over relaxation technique.In elasto-hydrodynamic lubrication,the finite element method with in iteration scheme is adopted to solve both Reynolds equation and the three-dimensional elasticity equation representing the displacement field in the bearing shell.The results show that the sound pressure level of the bearing is markedly influenced by the flexibility of the bearing liner,the viscosity of lubricant and the load applied to journal.HD analysis shows that the journal centre’s orbit,from a disturbed position,converges to the static equilibrium position faster than EHD lubrication.The results of the present paper could aid in the design of low-noise rotor-bearing systems supported by oil lubricated journal bearings.     

Effect of transmission error on the dynamic behaviour of gearbox housing

The dynamic response of gearbox remains a paramount concern because of noise generation. This work is concerned with numerical simulation of the overall dynamic behaviour of a parallel helical gear transmission. A dynamic sub-structuring method using different types of substructure (carrying and slave) is made to determine the natural frequencies and the corresponding mode shapes. The structure to be investigated is subdivided into components or sub-structures, which are then analyzed independently for natural frequencies and mode shapes. A numerical model taking into account the elastic coupling between the various components of a gearbox was developed. It allows studying and analyzing the dynamic behaviour of elastic housing in the presence of gear process. The static transmission error is introduced as a vibratory excitation source and it is represented by time-varying mesh stiffness. The discretization of the housing deformation energy and the kinetic energy expressions using plate finite elements leads to constructions of the stiffness and the mass matrixes. In dynamic analyses, time-discretization based on the Newmark method is used. The different equations governing movement of gearbox are established in a truncated modal base deduced from the average characteristics of the structure. A gearbox example is presented, and analyzed. A presentation and discussion of the numerical results was emphasized. The numerical results allow us to conclude on the dominant phenomena of the overall dynamic behaviour of the gear transmission.     

Robust Interactive Method for Hand Gestures Recognition Using Machine Learning

The Hand Gestures Recognition (HGR) System can be employed to facilitate communication between humans and computers instead of using special input and output devices. These devices may complicate communication with computers especially for people with disabilities. Hand gestures can be defined as a natural human-to-human communication method, which also can be used in human-computer interaction. Many researchers developed various techniques and methods that aimed to understand and recognize specific hand gestures by employing one or two machine learning algorithms with a reasonable accuracy. This work aims to develop a powerful hand gesture recognition model with a 100% recognition rate. We proposed an ensemble classification model that combines the most powerful machine learning classifiers to obtain diversity and improve accuracy. The majority voting method was used to aggregate accuracies produced by each classifier and get the final classification result. Our model was trained using a self-constructed dataset containing 1600 images of ten different hand gestures. The employing of canny's edge detector and histogram of oriented gradient method was a great combination with the ensemble classifier and the recognition rate. The experimental results had shown the robustness of our proposed model. Logistic Regression and Support Vector Machine have achieved 100% accuracy. The developed model was validated using two public datasets, and the findings have proved that our model outperformed other compared studies.     

Comparison of SPIN and VIS for protocol verification

In this paper, we compare and contrast SPIN and VIS, two widely used formal verification tools. In particular, we devote special attention to the efficiency of these tools for the verification of communications protocols that can be implemented either in software or hardware. As a basis of our comparison, we formally describe and verify the Asynchronous Transfer Mode Ring (ATMR) medium access protocol using SPIN and its hardware model using VIS. We believe that this study is of particular interest as more and more protocols, like ATM protocols, are implemented in hardware to match high-speed requirements. Published online: 1 March 2002     

Humidity-Sensing Characteristics of Divalent-Metal-Doped Indium Oxide Thin Films

Metal-doped indium oxide thin films that have been prepared on glass substrates via a dip-coating method from an aqueous sol show a rapid decrease in electrical conductivity at room temperature (by approximately three orders of magnitude) when brought into contact with moist air. This observation is in contrast to the conductivities of nondoped indium oxide films that are independent of moisture. Thus, the doped films can be applied as a humidity sensor. The film thickness has no substantial effect on the sensing properties, probably because of the porous nature of the films that are prepared by a sol-gel process. To examine the effects of film morphology, a comparison between the humidity-sensing properties of the films that have been prepared from organic and aqueous sols also has been conducted. The roles of the doped metal ions are also discussed.