Optimizing the Sharpening Process of Hybrid-Bonded Diamond Grinding Wheels by Means of a Process Model

The grinding wheel topography influences the cutting performance and thus the economic efficiency of a grinding process. In contrary to conventional grinding wheels, super abrasive grinding wheels should undergo an additional sharpening process after the initial profiling process to obtain a suitable microstructure of the grinding wheel. Due to the lack of scientific knowledge, the sharpening process is mostly performed manually in industrial practice. A CNC-controlled sharpening process can not only improve the reproducibility of grinding processes but also decrease the secondary processing time and thereby increase the economic efficiency significantly. To optimize the sharpening process, experimental investigations were carried out to identify the significant sharpening parameters influencing the grinding wheel topography. The sharpening block width lSb, the grain size of the sharpening block dkSb and the area-related material removal in sharpening V’’Sb were identified as the most significant parameters. Additional experiments were performed to further quantify the influence of the significant sharpening parameters. Based on that, a process model was developed to predict the required sharpening parameters for certain target topographies. By using the process model, constant work results and improved process reliability can be obtained.

The effect of the geometric structure of the modified slot die on the air field distribution in the meltblowing process

In order to reduce the fiber diameter and the energy consumption in the meltblowing process, a modified slot die with two blocks was designed in this article. The numerical calculation and the experimental verification of the airflow field under the modified slot die were carried out, and the effect of the block structure parameters on the air field was investigated. The research results indicate that compared to the common slot die, the modified slot die with the blocks could increase the velocity on the spinning line and reduce the rate of the temperature decay on the spinning line. When the block width and the block inclination angle lower, and the block height expands, it could increase the peak of the air velocity, the temperature and the turbulence intensity on the center line of the air field under the modified slot die. The average velocity on the spinning line of the modified die under the conditions of block width = 20 mm, block height = 30 mm and block inclination angle = 60° is the highest.

THE EFFECT OF RETENTION FORMS ON ACRYLIC BASE SURFACES ON ADHESIVE STRENGTH OF DENTURE RELINER MATERIALS

Background: Acrylic prosthesis that are used for a long time are often not sticky anymore and easy off. Treatment that can be done is relining, which is resurfacing with new material addition to prosthesis surface in contact with mucosa. One of materials used is denture reliner made of acrylic material (heat and self cured acrylic). The successful use of this reliner material depends on the retention of acrylic base surface. There is some retentions namely bur strokes, ethyl acetate and Al2O3 sandblast. Purpose: To determine effect of retention in form of bur strokes, Ethyl Acetate and Al2O3 sandblast on acrylic bases surface on adhesive strength of reliner denture material. Method: Research using samples in form of acrylic blocks with a length of 80mm, a large block width of 10 x10 mm and small block of 10 x 8 mm, reliner material thickness is 3 mm. Total of 64 samples were divided into 2 groups based on reliner materials (heat and self) and each group was divided into 4 groups based on treatment (control, bur stroke, ethyl acetat and Al2O33 sandblast). All samples were subjected to tensile test using UTM to obtain tensile strength values. Result: Heat CA tensile strength value was greater than self CA and the two groups were significantly different (p<0.05), while lowest tensile strength value in control group followed by ethyl acetate and largest value in Al2O3 sandblast and almost all groups were significantly different (p<0.05). Conclusion: Heat CA is more adhesive than self CA and retention on acrylic surface is proven to be effective in increasing adhesive strength of acrylic surface against denture reliner.

An improved heuristic-dynamic programming algorithm for rectangular cutting problem

In this paper, the two-dimensional cutting problem with defects is discussed. The objective is to cut some rectangles in a given shape and direction without overlapping the defects from the rectangular plate and maximize some profit associated. An Improved Heuristic-Dynamic Program (IHDP) is presented to solve the problem. In this algorithm, the discrete set contains not only the solution of one-dimensional knapsack problem with small rectangular block width and height, but also the cutting positions of one unit outside four boundaries of each defect. In addition, the denormalization recursive method is used to further decompose the sub problem with defects. The algorithm computes thousands of typical instances. The computational experimental results show that IHDP obtains most of the optimal solution of these instances, and its computation time is less than that of the latest literature algorithms.

ON THE COMPARATIVE ANALYSIS OF THE COOLEY-TUKEY AND BLUESTEIN NUMERICAL FAST FOURIER TRANSFORMS ALGORITHMS FOR DIGITAL SIGNAL PROCESSING

ABSTRACT This study was designed to compare the computing efficiency of C-TNADSP and the BNADSP to ascertain a more efficient numerical algorithm necessary for the processing of digital signals. The faster numerical algorithm established in this study is abbreviated with RCC-TNADSP (Resultant Compared C-TBNADSP). The methodology adopted in this work was comparative analysis development design. The major technologies used in this work are the C-TNADSP and BNADSP, and the c++. The c++ served as a signal processing language simulator (SPLS). The execution times of the Cooley-Tukey and the Bluestein algorithms were 3.44 seconds and 3.50 seconds respectively. On comparing the speeds of the fast Cooley–Tukey and the fast Bluestein algorithms we observed that the Cooley-Tukey algorithm has 0.06 seconds speed improvement over the Bluestein algorithm. In line with this outcome, we concluded that the Cooley-Tukey algorithm (C-TNADSP) is faster than the Bluestein algorithm (BNADSP). In the same vein the Cooley-Tukey algorithm (C-TNADSP) is therefore the fastest DSP algorithm. This is however faster than the spectrum of FFT algorithms of O(nlogn) computing speed. The algorithms were tested on input block width 1000 units, and above, and can be implemented on input size of 100 000, and 1000 000 000 without the challenge of storage overflow. The input samples tested in this work was the discretized pulse wave form with undulating shape out of which the binary equivalents were extracted. Other forms of signals may also be tested in this fast algorithm provided they are interpreted in the digital wave type. KEYWORDS: Algorithm, FFT, Cooley-Tukey, Bluestein, Comparison, Analysis, FFT

Simple adjustment of the sequence weight algorithm remarkably enhances PSI-BLAST performance

PSI-BLAST, an extremely popular tool for sequence similarity search, features the utilization of Position Specific Scoring Matrix (PSSM) constructed from a multiple sequence alignment (MSA). PSSM allows the detection of more distant homologs than a general amino acid substitution matrix does. An accurate estimation of the weights of sequences in an MSA is crucially important for PSSM construction. PSI-BLAST divides a given MSA into multiple blocks, for which sequence weights are calculated. When the block width becomes very narrow, the sequence weight calculation can be difficult.We demonstrate that PSI-BLAST indeed generates a significant fraction of blocks having widths less than 5, thereby degrading the PSI-BLAST performance. We revised the code of PSI-BLAST to prevent the blocks from being narrower than a given minimum block width (MBW). We designate the modified application of PSI-BLAST as PSI-BLASTexB. When MBW is 25, PSI-BLASTexB notably outperforms PSI-BLAST consistently for three independent benchmark sets. The performance boost is even more drastic when an MSA, instead of a sequence, was used as a query.Our results demonstrate that the generation of narrow-width blocks during the sequence weight calculation is a critically important factor that restricts the PSI-BLAST search performance. By preventing narrow blocks, PSI-BLASTexB remarkably upgrades the PSI-BLAST performance.

Numerical and experimental analysis of heat sealing of multi-layered laminate films used in lithium polymer battery packaging

The packaging of a lithium polymer secondary battery involves a wrapping process of an aluminum/polymer laminate film that uses heat sealing. Heat sealing time and sealing block width are important variables in creating packaging requirements for optimal battery performance and safety. In this study, a heat transfer analysis is performed using finite element method to investigate the temperature distribution of the sealing block over the course of the heat sealing process. Heat sealing time and sealing block width were the variables of interest for the heat transfer simulation in order to identify optimal manufacturing conditions. Through the analysis, we successfully identified a minimum heat sealing time less than 3 s and 1.5 mm width of the sealing block that optimizes both the rate of battery production and lithium polymer battery capacity. To validate the quality of heat sealing properties, visual inspection and restrained packaging tests were performed.

Effects of Microstructure Transformation on Strengthening and Toughening for Heat-Treated Low Carbon Martensite Stainless Bearing Steel

Microstructural transformations and mechanical properties of a low carbon martensite stainless bearing steel treated with different heat treatment parameters and cryogenic treatment (-82°C) were investigated. The function of microstructural transformations on strengthening and toughening process was quantitatively characterized as well. These analyses were performed by the optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and electron back scattering diffraction (EBSD) technique. The obtained results show that with execution of cryogenic treatment and tempering, the tensile strength increase owing to the reduction of retained austenite and fine carbides precipitating respectively. The effect of martensitic microstructure on yield strength increment can be regarded as packet size and block width which conform to Hall-Petch relationship. Meanwhile, the results suggest that the block width is the key structural controlling unit when analyzing the strength-structure relationship of lath martensite in low carbon martensite stainless bearing steel. In addition, packet size can be related to toughness controlling as well because of the same size as cleavage plane.

Radiation dose distribution under the area protected using a Cerrobend block during external beam radiotherapy: a film study

BackgroundIn radiation therapy, to spare normal surrounding tissues, either Multileaf Collimators or Cerrobend blocks are used.PurposeThe current study focuses on the relative dose distribution under the areas protected by Cerrobend blocks.Materials and methodsA dual-energy linear accelerator and a Cobalt-60 machine were utilised as radiation sources. Several blocks were designed using commercially available materials to shield radiation fields. The relative dose distribution was then evaluated using extended dose range 2 films.ResultsResults showed that the dose distribution under protected areas depends on several parameters including the width and height of protecting blocks, incident photon beam energy, radiation field size and source to surface distance. An increase in Cerrobend block height from 80 to 95 mm significantly decreases the dose at the protected areas.ConclusionAn increase in the block width and photon energy decreases the relative dose deposition at the protected area. However, electron and neutron contaminations should also be taken into consideration.