Marginal Distortion Research Articles

Discrete Wavelet Transform based Cryptosystem

In this article, the authors proposed, implemented and analysed a symmetric key cryptographic algorithm that can be considered as a lossless encryption and decryption technique, advantageous especially in situations where, even a slight marginal distortion is not tolerable. In the proposed system, Haar wavelet is used initially, to transform the original target image into its frequency domain, followed by encrypting the resulting sub-bands, so as to obtain a secure and reliable encrypted image. The resulting coefficients after Haar decomposition is scattered using a reversible weighing factor, suitably reversed and swapped to get the secure encrypted image. The encrypted image is then correspondingly decrypted, by the reverse process to get back the original decrypted image. Statistical testing and security methods were used to evaluate and analyse the proposed cryptosystem and the results showed that the proposed system is cryptographically resistant to attacks and is also highly secure when compared to other cryptographic systems in the frequency domain.

Gibson and Pictures in Perspective: Reverse the Directions.

In his extensive writing about pictures, James J. Gibson offered perspective formulae for square tiles projecting trapezoids onto a picture plane, foreshortening to zero height with distance. I reverse the claim: as distance decreases, the trapezoids increase to infinite height, in marginal distortion, or forelengthening. I also reverse the direction of projection. Usually considered to be incoming, from the distant tile to the picture plane, in reverse—outgoing—the tiles have directions from the center of projection, with implications for haptics and people who are blind. A drawing of a cube illustrates the argument. It is by an adult who is blind. It includes foreshortening, and shows directions of surfaces from a vantage point.

Pulse optimization for all-optical switching engineered in photonic crystal waveguide with micro-resonator

We have investigated switching properties and especially pulse shape preservation in the process of all-optical switching. To this end, we made two different designs of all-optical switches based on two-dimensional (2D) photonic crystal (PC) waveguides with different dispersive properties and micro-resonators with different quality factors. We realized numerically that all-optical switching without or with marginal temporal pulse distortion can be obtained under precisely chosen conditions on pulse duration and detuning. In particular, the former has to be approximately 2.5 times longer than cavity buildup time and the latter has to be equal to one full width at half maximum of the cavity transmission spectrum.

2 純チタン陶材焼き付け鋳造冠の焼成過程における変形と焼き付け強度に関する研究 (第452回 大阪歯科学会例会)

2 純チタン陶材焼き付け鋳造冠の焼成過程における変形と焼き付け強度に関する研究 (第452回 大阪歯科学会例会)

Evaluation of effects of porcelain firing on the marginal fit changes of porcelain–fused-to -metal crown fabricated utilizing two different margin designs and two commercially available base metal alloys

Aim: To find the marginal fit of the porcelain fused to metal crowns by two different margin designs (shoulder and chamfer) and two commercially available base metal alloys.Material and Methods: Tooth preparation of first central incisor for porcelain-fused-to-metal crown with shoulder margin and second incisor for porcelain-fused-to-metal crown with chamfer margin was done. Wax pattern of the same was prepared. Impression of both prepared ivorine incisors was made by light body impression material and poured with pattern resin. Both the patterns were invested and casted with cobalt chromium alloy for making master dies. Two wax patterns of unprepared central incisors were fabricated, one with shoulder margin and another with chamfer margin. These patterns were then cut back to the size of the coping. Four rings were invested. In each ring ten patterns, five with shoulder margin and five with deep chamfer margin were sprued together to ensure that each group would pass through the same investing and casting procedure, followed by ceramic firing and measurement.Results: Marginal fit change or marginal discrepancy (before and after firing) between the groups was highly significant.Conclusions: Veneered crowns exhibited highly significant marginal distortion than non- veneered copings after porcelain firing. Shoulder margin is better in minimizing marginal discrepancy compared to deep chamfer margin. Marginal discrepancy is less when cerabond base metal alloy is used with shoulder margin as compared to commend base metal alloy used for shoulder margin.

웨이브렛 변환 계수의 특성을 이용한 생체 영상 암호화 알고리즘

Lossless encryption methods are more applicable than lossy encryption methods when marginal distortion is not tolerable. In this research, the author propose a novel lossless symmetric key encryption/decryption technique. In the proposed algorithm, the image is transformed into the frequency domain using the lifting wavelet transform, then the image sub-bands are encrypted in a such way that guarantees a secure, reliable, and an unbreakable form. The encryption involves scattering the distinguishable frequency data in the image using a reversible weighting factor amongst the rest of the frequencies. The algorithm is designed to shuffle and reverse the sign of each frequency in the transformed image before the image frequencies are transformed back to the pixel domain. The results show a total deviation in pixel values between the original and encrypted image. The decryption algorithm reverses the encryption process and restores the image to its original form. The proposed algorithm is evaluated using standard security and statistical methods; results show that the proposed work is resistant to most known attacks and more secure than other algorithms in the cryptography domain.

Single-pass, efficient type-I phase-matched frequency doubling of high-power ultrashort-pulse Yb-fiber laser using $${\rm LiB}_3{\rm O}_5$$ LiB 3 O 5

We report 48 % efficient single-pass second harmonic generation of high-power ultrashort-pulse (\({\approx }250\,{\rm fs}\)) Yb-fiber laser by utilizing type-I phase matching in \({\rm LiB}_3{\rm O}_5\) (LBO) crystal. The choice of LBO among other borate crystals for high-power frequency doubling is essentially motivated by large thermal conductivity, low birefringence and weak group velocity dispersion. By optimally focussing the beam in a 4-mm-long LBO crystal, we have generated about 2.3 W of average power at 532 nm using 4.8 W of available pump power at 1064 nm. The ultrashort green pulses were found out to be near-transform limited \({\rm sech}^2\) pulses with a pulse width of \(\Delta \tau \approx 150\,{\rm fs}\) and being delivered at 78 MHz repetition rate. Due to appreciably low spatial walk-off angle for LBO (\({\approx }0.4^{\circ }\)), we obtain \(M^2<1.26\) for the SH beam which signifies marginal distortion in comparison with the pump beam (\(M^2<1.15\)). We also discuss the impact of third-order optical nonlinearity of the LBO crystal on the generated ultrashort SH pulses.

Apparent Distortions in Photography and the Geometry of Visual Space

In this paper I contrast the geometric structure of phenomenal visual space with that of photographic images. I argue that topologically both are two-dimensional and that both involve central projections of scenes being depicted. However, I also argue that the metric structures of the spaces differ inasmuch as two types of “apparent distortions”—marginal distortion in wide-angle photography and close-up distortions—which occur in photography do not occur in the corresponding visual experiences. In particular, I argue that the absence of marginal distortions in vision is evidence for a holistic metric of visual space that is spherical, and that the absence of close-up distortions shows that the local metric structure possesses a dynamic variable curvature which is dependent upon the distance away of objects being viewed at a given time.

Image cryptographic algorithm based on the Haar wavelet transform

Lossless encryption methods are more applicable than lossy encryption methods when marginal distortion is not tolerable. In this research, the authors propose a novel lossless symmetric key encryption/decryption technique. In the proposed algorithm, the image is transformed into the frequency domain using the Haar wavelet transform, then the image sub-bands are encrypted in a such way that guarantees a secure, reliable, and an unbreakable form. The encryption involves scattering the distinguishable frequency data in the image using a reversible weighting factor amongst the rest of the frequencies. The algorithm is designed to shuffle and reverse the sign of each frequency in the transformed image before the image frequencies are transformed back to the pixel domain. The results show a total deviation in pixel values between the original and encrypted image. The decryption algorithm reverses the encryption process and restores the image to its original form. The proposed algorithm is evaluated using standard security and statistical methods; results show that the proposed work is resistant to most known attacks and more secure than other algorithms in the cryptography domain.

A Comparative Study of the Effect of Four Consecutive Firing Cycles on the Marginal Fit of All: Ceramic Crown System and Metal Ceramic Crown System

The marginal fit of new all ceramic crown system. To know the marginal adaptability of new all ceramic systems. Finesse all ceramic system and traditional metal ceramic system total 15 samples of all ceramic (test group) and 15 samples of metal ceramic crown system (control group) were fabricated and tested for marginal distortion at four firing cycles using image analyzer and special software (Leco Version La 32) in which instead of measuring at points an area was measured that gives a computed mean measured thickness of marginal distortion. Value obtained were evaluated for significance using two tailed, unpaired, student t test and Tukeys-Kramer multiple comparison test. Finesse all ceramic crown system showed continued clinically acceptable marginal distortion through all firing cycles (12.84μm). Greatest distortion of metal ceramic system occurred during degassing cycle(16.90μm). In respect of marginal fit all ceramic (finesse) crowns is better choice when esthetics is more concern.

Real-Time Communications in Autonomic Networks: System Implementation and Performance Evaluation

This paper describes the design and prototype implementation of a communication platform aiming to provide voice and video communication in a distributed networking environment. Performance considerations and network characteristics have also been taken into account in order to provide the set of properties dictated by the sensitive nature and the real-time characteristics of the targeted application scenarios. The proposed system has been evaluated both by experimental means as well as subjective tests taken by an extensive number of users. The results show that the proposed platform operates seamlessly in two hops, while in the four hops scenario, audio and video are delivered with marginal distortion. The conducted survey indicates that the user experience in terms of Quality of Service has obtained higher scores in the scenario with the two hops.

A comparison of marginal fit of glass infiltrated alumina copings fabricated using two different techniques and the effect of firing cycles over them

PURPOSEThis study evaluated marginal fit of glass infiltrated alumina cores fabricated using two techniques and their marginal stability after firing cycles of veneering porcelain.MATERIALS AND METHODSFifteen standardized all-ceramic crowns were fabricated on a metal die using each technique: slip cast technique of VITA In-Ceram sprint Alumina (Group A as control) and plastic foil matrix technique of Turkom-Cera fused alumina core system (Group B). Copings were compared between groups and within groups at coping stage and after firing each layer of veneering porcelain. A device was used to standardize seating of copings on the metal die and positioning of the specimens under the microscope after each stage of fabrication. The specimens were not cemented and marginal gap was measured using an image analyzing software (Imagepro Express) on the photographs captured under an optical microscope. Two tailed unpaired 't test' was used to compare marginal gaps in two groups and one way ANOVA was used to analyze marginal distortion within each group at 95% confidence interval.RESULTSThe marginal gap was smaller at the coping stage in group B (60 + 30 µm) than group A (81 + 21 µm) with statistical significance. After firing of veneering porcelain the difference was insignificant. At the final stage, both groups exhibited lower mean marginal gaps than at the initial coping stage with the difference of 11.75 µm for group A and 11.94 µm for group B, but it was statistically insignificant due to high value of standard deviation.CONCLUSIONWithin the limitations of this study, it was concluded that both techniques produced copings with comparable and acceptable marginal fit and marginal stability on firing veneering porcelain.

Emission taxes and optimal refunding schemes

We examine how refunding emission taxes to firms dependent on market shares should be designed. While refunding is harmful under perfect competition, a first-best self-financing tax/tax-refunding scheme exists if the marginal damage from pollution exceeds the marginal distortion in an imperfectly competitive output market with symmetric firms. Under pre-investment in cleaner technology with short-term abatement opportunities, a first-best refunding scheme exists if pollution refunding can be made dependent on both market and investment shares.

Tax Reforms and Environmental Policies for Italy

This paper focuses on the relationship between tax reforms and environmental quality in Italy. First, we analyse some of the characteristics of the tax system. Within a dynamic model, we estimate the marginal distortion introduced by different taxes and show that the system is far from being optimal, at least in terms of efficiency. We then consider some possible tax reforms, keeping into account both the effect on utility and the impact on pollution. Finally, we design a tax reform with a specific environmental goal, i.e. the reduction of polluting emissions by 10%, and show the economic effects of this policy.

Bond strength of porcelain fused to pure titanium and marginal distortion during the firing cycle

Bond strength of porcelain fused to pure titanium and marginal distortion during the firing cycle

On the use of the classical tests for detecting linkage.

Some drawbacks of the classical Mather's linkage text XL2 are considered, and the simple contingency analysis is suggested as an alternative method. The former test is conditional on Mendelian segregation at both loci, whereas the simple contingency test is not. Furthermore, the contingency test and the test for Mendelian segregation at each locus are orthogonal when performed using the G statistic. Simulation results show that, when the XL2 is used, the actual type I error probability (alpha a) can be dramatically perturbed. As expected, no alpha a perturbation is observed when the G contingency test is used. On the other hand, when segregation is Mendelian at both loci, the power of the XL2 method is larger than that of the contingency G test when sample size is small and strong marginal distortion is observed. Because strong marginal distortion may suggest that segregation may be non-Mendelian, the XL2 is in general discouraged in favor of the simple contingency analysis.

Effect of incompatibility stress on the fit of metal-ceramic crowns.

The interactive effect of coping thickness and a positive thermal contraction mismatch between metal and porcelain on the fit of metal-ceramic crowns has not yet been experimentally determined. Previous studies have suggested that marginal distortion may be due to contraction differences, although finite element analyses indicate that these distortion effects should be negligible. The marginal gap between metal-ceramic crowns and prepared dies was determined under conditions designed to exaggerate distortion effects. These included the use of thin metal copings (0.1 and 0.2 mm), a chamfer preparation, an alloy with relatively poor creep resistance, and a large thermal contraction mismatch between the alloy and porcelain layers. Gap changes which resulted during porcelain firing cycles were relatively small, but larger marginal discrepancies developed in crowns prepared with a compatible porcelain during grinding and abrasive blasting procedures. This study conclusively demonstrates that incompatibility stress induced by a positive contraction mismatch is not a primary cause of marginal or generalized distortion of metal-ceramic crowns and suggests that external grinding and internal abrasive blasting of crowns are more likely causes of this effect.

Distortion of ceramometal fixed bridges by heat treatment

Notable distortion and displacement of the ceramometal fixed bridge frame occur in presoldering and degassing phases through laboratory procedures. In porcelain-fused-to-precious-metal crown, heat treatment before grinding is said to prevent marginal distortion. There is no research, however, on this heat treatment to make ceramometal fixed bridges or to assemble them by pre-sol dering.The author studied the heat treatment effects on distortion and displacement of ceramometal fixed bridges compared with ones not treated by heat. The frames were measured three-dimensional deviations after the indexing for the heat treatment, pre-soldering, surface grinding of the frame, degassing, opaque porcelain firing, body-incisor porcelain firing and glazing.The results were as follous:1. In pre-soldering and degassing phases, the heat-treated frames produced significantly smaller distortion and displacement than not heat-treated ones.2. In opaque porcelain firing, body-incisor porcelain firing and glazing phases, the heat-treated frameworks were not significantly different from ones not treated by heat.3. It was therefore explicated that the heat treatment before grinding is the effective method of producing ceramometal bridges in decreasing distortion and displacement expected in labolatory procedures.

Marginal distortion of cast restorations induced by cementation

Eleven full veneer crowns were directly constructed on brass stylized dies. Crown marginal openings and vertical heights were measured before and after cementation with zinc phosphate cement. The following results were established. 1. 1. The marginal opening of complete veneer gold crowns increased during cementation. 2. 2. The vertical heights of well fitting crowns also increased significantly after cementation.

Effect of metal design on marginal distortion of metal-ceramic crowns.

An analysis of residual stress and marginal distortion due to thermal contraction mismatch between metal and ceramic is presented for metal-ceramic crowns. Using dilatometric data, finite element stress analyses were performed on pre-molar crowns designed with chamfer-knife edge, chamfer with collar, shoulder with collar, and shoulder-bevel with collar geometries and a maxillary central incisor crown with a chamfer-knife edge geometry. Calculations were made using combinations of a Ni-Cr alloy or a Au-Pd alloy with each of three porcelain products. Calculated marginal distortions due to crown design and metal-porcelain thermal contraction incompatibility were found to be well below experimental values found in the literature. For the cases studied, the calculated marginal distortions due to metal-porcelain thermal contraction mismatch depend primarily on the metal-porcelain combination and are insensitive to the coping design. However, this study excluded copings which have been extensively ground to thicknesses of 0.1 mm or less, and such copings may be more susceptible to localized or generalized distortion.