Optimal Slope Research Articles

The rate-distortion optimized quantization algorithm in Compressive Sensing

Rate-distortion optimization greatly improves performance of compression coding system. In this paper, the rate-distortion optimized quantization algorithm is proposed for block-based Compressive Sensing. Compressive Sensing is the emerging technology which can encode a signal into a small number of incoherent linear measurements and reconstruct the entire signal from relatively few measurements. In the algorithm the sampling measurements are quantized optimally based on the rate-distortion theory. For the coefficients near dead-zone the quantization level with best rate-distortion performance is chosen. Moreover, in order to acquire the best performance, a fast Lagrange multiplier solving method is proposed to find the optimal slope λ* of the rate-distortion curve at the given bit budget. Experimental results show that the proposed algorithm improves objective and subjective performances substantially. The average gain about 0.7dB can be achieved with the same rate.

The Parameters Optimization of Bionic Tongue Block Based on the Discrete Element Method

Human tongue has complex structure and involves in chewing function, such as transporting and mixing foods. In order to develop tongue block of the bionic chewing equipment to make the food materials slide from the lingual surface to the tooth surface as much as possible in the same time, three-dimensional model of tongue block was built according to the geometric shape and physiology characteristic of the human tongue. The discrete element method was used to simulate the whole delivery process of food materials to teeth area, and then the geometrical parameters of the tongue block were optimized. The simulated results showed that when the height of the tongue tip and the tongue root were fixed, the optimal slope angles which have the decisive effect on the process of food materials slide were 32°and 2° respectively. The results provided a theoretical basis for the processing of tongue block of the bionic chewing equipment.

Assessment of solar radiation on diversely oriented surfaces and optimum tilts for solar absorbers in Malaysian tropical latitude

In this paper, the solar radiation on diversely oriented surfaces and optimum tilts for solar absorbers were assessed. The KT solar radiation model was coded in the MATLAB-based environment to compute the monthly solar radiation values. Seven-year data of monthly average daily solar radiation on a horizontal surface in Bangi, Malaysia (latitude = 3°N) were adopted as input in the simulation programme and the results were compared with the local optimum tilt angle at solar noon and other solar radiation model. The contour mappings of solar irradiation at various orientations in 12 months were presented. Results showed that the surface tilted ≤20° could intercept a relatively high solar intensity, which was less sensitive to the variation of azimuths with average solar insolation deviation of 11.82 %. The monthly optimum tilt angle altered throughout the year, ranging from −24° (in equator direction) to +22° (in north direction). The estimated annual optimum slope, 1.4° facing to the equator, was close to local latitude. Based on the seasonal analysis, the north-facing surface was able to intercept higher daily average solar radiation energy compared to south-facing plane. The optimum angles for seasonal south- and north-facing surfaces were found to be 14.4° and 14.8°, respectively, with a tolerable slope deviation of ±5° from the optimal values in the present work.

Optimum slope angles and the corresponding uncertainties for a solar collector

Determination of the optimum slope angle of a solar collector is highly dependent on the incident solar radiations on the collector surface. As collected instantaneous data of incident solar radiation values are averaged, more attention must be directed towards these figures by determining the uncertainties in these measurements as this allows the calculation of the optimum slope angle. These average solar radiations give a definite optimum slope angle if they come along with the lowest uncertainties. Hence, this study aimed to find the optimum slope angles of solar collectors with corresponding uncertainties. For doing this, the solar radiation data borrowed from the Iranian Meteorological Organization which were measured on a horizontal surface in a period of 20 years (1986–2005), were employed. The results showed that the uncertainties of the optimum slope angles in some cities were quite high and it indicated that in this case more attention should be paid to select the appropriate optimum slope angle. These changes were more in cold regions compared to hot and dry regions because the weather in the colder climates is typically more transient than the weather in hot and dry climates.

Collector Simulation Model with Dynamic Incidence Angle Modifier for Anisotropic Diffuse Irradiance

The incidence angle modifier (IAM) of a solar thermal collector for diffuse irradiance is usually determined under the simplifying assumption of isotropic sky and ground radiance. It is applied as one constant collector parameter, independent from slope or weather conditions. The simulation model introduced here considers the varying anisotropy of sky radiance. To create realistic distributions, the approach of Brunger and Hooper is used. Three modes are possible: Mode 1 calculates separate IAMs for anisotropic sky (for every time step) and isotropic ground. Mode 2 calculates separate IAMs for isotropic sky and isotropic ground (once per simulation). Mode 3 uses a user-specified isotropic IAM-value for the collector hemisphere.The model is applied to a stationary, double-covered process heat flat-plate collector with one-sided CPC booster reflector (RefleC). This collector shows a biaxial and asymmetric IAM for direct irradiance. It is found that, compared to anisotropic modeling, the simplified isotropic model is undervaluing the annual output of this collector by 13.7% for a constant inlet temperature of 120°C in Würzburg, Germany. At 40°C inlet temperature the undervaluation is 9.3%. For the basis flat-plate without reflector the undervaluation is 7.5% at 120°C and 3.3% at 40°C. An annual irradiation distribution diagram shows that this is due to an underestimation of diffuse irradiation from directions with high direct irradiation. Detailed results reveal that for RefleC the IAM for anisotropic diffuse sky radiance can vary by up to approx. 25 percentage points during one day.It is concluded that isotropic modeling of diffuse irradiance can be expected to significantly undervalue the annual output of all non-focusing solar thermal collectors. Highest relevance is found for high collector slopes, complex IAMs and at low-efficiency operation. The optimal collector slope is almost not affected. Accuracy of existing models can be increased by applying Mode 2.

Assessment of solar radiation on diversely oriented surfaces and optimum tilts for solar absorbers in Malaysian tropical latitude

In this paper, the solar radiation on diversely oriented surfaces and optimum tilts for solar absorbers were assessed. The KT solar radiation model was coded in the MATLAB-based environment to compute the monthly solar radiation values. Seven years data of monthly average daily solar radiation on a horizontal surface in Bangi, Malaysia (latitude = 3° N) was adopted as input in the simulation programme, and the results were compared with the local optimum tilt angle at solar noon and other solar radiation model. The contour mappings of solar irradiation at various orientations in 12 months were presented. Results showed that the surface tilted at ≤20° could intercept a relatively high solar intensity, which was less sensitive to the variation of azimuths with average insolation deviation of 11.82%. The monthly optimum tilt angle altered throughout the year, ranging from -24° (in equator direction) to +22° (in north direction). The estimated annual optimum slope, 1.4° facing to the equator, was close to local latitude. Based on the seasonal analysis, the north-facing surface was able to intercept higher daily average solar radiation energy compared to south-facing plane. The optimum angles for seasonal south- and north-facing surfaces were found to be 14.4° and 14.8°, respectively, with a tolerable slope deviation of ±5° from the optimal values in the present work.

Flat-plate collector construction and system configuration to optimize the thermosiphonic effect

Thermosiphon systems heat potable water or heat transfer fluid and use natural convection to transport it from the collector to storage. This type of technology is applied extensively in countries with good sunshine potential. One such example is Cyprus, which is currently the leading country in the world with respect to the application of solar water heaters for domestic applications, with more than 93% of the houses equipped with such a system. The performance of such a system depends on many factors including the collector construction and the arrangement of the system, mainly with respect to the distance between the top of the solar collector and the bottom of the storage tank and the solar collector slope, which affects both the energy collected and the hydrostatic pressure of the system. A typical system in Cyprus uses 3 m2 of collectors, 160 l storage, its collectors are usually inclined at 45° from horizontal and has 15 mm copper riser tubes and header tubes with a diameter of 28 mm. The collector absorber plate is also made from copper. The main objective of this paper is to investigate through modeling and simulation possible configurations, which will optimize the performance of the system. For this purpose, a number of riser and header tube diameters were considered ranging from 6 mm to 35 mm, slopes from 20° to 90° and distances between the top of the collector to the bottom side of the storage tank ranging from ±15 cm. The system is modeled using TRNSYS and simulated with the Typical Meteorological Year (TMY) of Nicosia, Cyprus. The results showed that the best-optimized system is obtained for small header and riser pipe diameters and very close performance is obtained for various combinations. Therefore, the decision on the optimum system should depend on cost issues, which are currently very important because of the increased price of copper and operational problems depending on the hardness of the water in the area of installation, which could cause scale deposits that could clog the riser pipes. The optimum slope is found to be equal to the latitude plus 10°, i.e., 45°, although a smaller slope does not affect the performance a lot, and the optimum distance between the top of the collector and the bottom of the storage tank is −15 cm. These findings should prove valuable for the collector and systems designers and manufacturers.

Dump Load Shedding and Slope Angle of Optimization Design

In view of the local conditions of Xingshan Iron Mine North Dump, an economically safe load shedding scheme was determined. Based on critical sliding field technology, the most dangerous slip surface can be searched of different waste-dump slope angles. Once the most dangerous slip surface is fixed, limit equilibrium methods can be used to analyze the stability of the slope. The corresponding slope angle of minimum allowable safety coefficient under the most unfavorable condition was defined as the optimal slope angle of this section, and the minimum optimal slope angle of all the sections of dump was determined as the final optimal slope angel of the whole dump. This method was not any practical but also extremely economical, which can ensure the absolute safety of dump and its surroundings.

Collapse behavior of single-layer space barrel vaults under non-uniform support settlements

Single-layer space barrel vaults are appropriate structures for covering extensive spaces with large spans for which non-uniform support settlement is considered as a great concern. This can affect the stability and collapse behavior of these structures. Accordingly, in this paper, the collapse behavior of the barrel vaults with different slope angles is investigated under various types of the non-uniform support settlement. Both material and geometrical nonlinearity are taken into account while studying the effects of the settlements on the collapse progression in barrel vaults. Finally, the optimum slope angles of the structures are determined so that it minimizes the destructive effects of the support settlement. Moreover, the allowable values of the non-uniform support settlements provided by several code provisions have been investigated in detail.

Optimization of slope angle and its seismic stability: A case study for the proposed open pit coalmine in Phulbari, NW Bangladesh

The present study reflects upon the results of substantial program of two-dimensional Finite Element Method (FEM) numerical analyses of the open pit that links to slope angle optimization associated with the safety factor of the pit slope of a coal mine in Bangladesh. In the present analyses, two types of models have been presented. The first model estimates safety factor without seismic effect on the overall pit slope of the model; the second model incorporates safety factor with seismic stability of the model. The calculated optimum slope angle of the first model is 31° with a rational safety factor of 1.51, prior to the seismic effect. However, the value is reduced to 0.93, 0.82, and 0.72, after we applies the seismic effect in the second model with M6, M6.5, and M7, respectively. Finally, our modeling results emphasize that for the case of the proposed Phulbari coalmine, there is extremely high prospect for causing massive slope failure along the optimum pit slope angle with 31° if the mine area felt seismic shaking, like the Sikkim (in northern India) earthquake with M6.9 on September 18, 2011.

A discontinuous Galerkin method for solving the fluid and magnetohydrodynamic equations in astrophysical simulations

A discontinuous Galerkin (DG) method suitable for large-scale astrophysical simulations on Cartesian meshes as well as arbitrary static and moving Voronoi meshes is presented. Most major astrophysical fluid dynamics codes use a finite volume (FV) approach. We demonstrate that the DG technique offers distinct advantages over FV formulations on both static and moving meshes. The DG method is also easily generalized to higher than second-order accuracy without requiring the use of extended stencils to estimate derivatives (thereby making the scheme highly parallelizable). We implement the technique in the AREPO code for solving the fluid and the magnetohydrodynamic (MHD) equations. By examining various test problems, we show that our new formulation provides improved accuracy over FV approaches of the same order, and reduces post-shock oscillations and artificial diffusion of angular momentum. In addition, the DG method makes it possible to represent magnetic fields in a locally divergence-free way, improving the stability of MHD simulations and moderating global divergence errors, and is a viable alternative for solving the MHD equations on meshes where Constrained-Transport (CT) cannot be applied. We find that the DG procedure on a moving mesh is more sensitive to the choice of slope limiter than is its FV method counterpart. Therefore, future work to improve the performance of the DG scheme even further will likely involve the design of optimal slope limiters. As presently constructed, our technique offers the potential of improved accuracy in astrophysical simulations using the moving mesh AREPO code as well as those employing adaptive mesh refinement (AMR).

Study on Optimization Method of the Slope Angle Design for Open-Pit Mine

The critical slip field theory is applied to optimization design of the slope angle. An intelligent matching optimization of the slope angle design is carried out based on the strata distribution, mechanics parameters of rock mass and a given security reserve. That is the implementation of the maximum allowable slope angle of slope rock mass under the given conditions. Optimized by the final highwall of Buzhaoba Open-Pit Mine, the overall slope angle increased 3°compared to the original design. Which implement the optimum slope angle of final highwall, modified the shortcoming in the original design and ensure the maximization of mine safety and the resource exploitation.

Correlation of Risk Analysis Method Results with Numerical and Limit Equilibrium Methods in Overall Slope Stability Analysis of Southern Wall of Chadormalu Iron Open Pit Mine-Iran / Korelacja wyników analizy ryzyka z wynikami obliczeń numerycznych oraz wynikami uzyskanymi w oparciu o metodę równowagi granicznej zastosowanych do badania stabilności wyrobiska pochyłego na południowej ścianie odkrywkowej kopalni rud żelaza w chadormalu w

Slope stability analysis is one of the most important factors in designing open pit mines. Therefore an optimal slope design that supports both aspects of economy and safety is very significant. There are many different methods in slope stability analysis including empirical, limit equilibrium, block theory, numerical, and probabilistic methods. In this study, to analyze the overall slope stability of southern wall of Chadormalu iron open pit mine three numerical, limit equilibrium and probabilistic methods have been used. Software and methods that is used for analytical investigation in this study are FLAC software for numerical analysis, SLIDE software and circuit failure chart for limit equilibrium analysis and qualitative fault tree and semi-quantitative risk matrix for probabilistic analysis. The results of all above mentioned methods, was a circular failure occurrence in Metasomatite rock zone between 1405 to 1525 m levels. The main factors of failure occurrence in this range were heavily jointing and existing of faults. Safety factors resulted from numerical method; Circular chart method and SLIDE software are 1.16, 1.25 and 1.27 respectively. Regarding instability and safety factors in Metasomatite rock zone, in order to stabilize the given zone, some considerations such as bench angle and height reduction should be planned. In results of risk matrix method this zone was mentioned too as a high risk zone that numerical and limit equilibrium methods confirmed this.

Estimated preejection period (PEP) based on the detection of the R-wave and dZ/dt-min peaks in ECG and ICG

The validity of estimating the PEP from a fixed value for the Q-wave onset to the R-wave peak (QR) interval and from the R-wave peak to the dZ/dt-min peak (ISTI) interval is evaluated. Ninety-one subjects participated in a laboratory experiment in which a variety of physical and mental stressors were presented and 31 further subjects participated in a sequence of structured ambulatory activities in which large variation in posture and physical activity was induced. PEP, QR interval, and ISTI were scored. Across the diverse laboratory and ambulatory conditions the QR interval could be approximated by a fixed interval of 40 ms but 95% confidence intervals were large (25 to 54 ms). Multilevel analysis showed that 79% to 81% of the within and between-subject variation in the RB interval could be predicted by the ISTI. However, the optimal intercept and slope values varied significantly across subjects and study setting. Bland-Altman plots revealed a large discrepancy between the estimated PEP and the actual PEP based on the Q-wave onset and B-point. It is concluded that the estimated PEP can be a useful tool but cannot replace the actual PEP to index cardiac sympathetic control.

Optimization of the complex slip surface and its effect on the hydrodynamic performance of two-dimensional lubricated contacts

In micro-electro-mechanical-system (MEMS) containing moving components, there is a need to achieve low friction and high load carrying capacity by lubrication. The aim of this paper is to study the hydrodynamic performance of a two-dimensional lubricated sliding contact in which one of the solid surfaces is designed such that partly slip boundary takes place, i.e. the complex slip surface (CSS). The approach is to use the genetic algorithm for determining the optimized complex slip surface (CSS) pattern as well as an optimized slope incline ratio simultaneously. A surface with an optimized complex slip surface (CSS) pattern in a lubricated contact generates many advantages compared to a surface without slip. The sliding surfaces considered show that the maximum load carrying capacity can be increased by approximately three times when compared to what the traditional hydrodynamics (no-slip) predict for a lubricated slider with an optimal slope incline ratio. The friction force can also be decreased significantly. The effect of an optimized complex slip surface on the hydrodynamic performance is much larger at a low initial critical shear stress than at a high initial critical shear stress. Numerical analyses indicate that varying the location and size area of the CSS pattern by taking into account the transverse direction (perpendicular to the sliding direction) in the optimization process, significantly affects the hydrodynamic performance.

Engineering Properties and Landfill of Stabilized Sludge

The present environmental regulations in China require sludge to be disposed of in a safe and environmentally sound manner. This paper presented an investigation on methods to stabilize wastewater sludge and stability evaluation of stabilized sludge landfill. Laboratory studies were conducted to determine the feasibility of solidifying and stabilizing sludge using fly ash, lime, and clay at varied mixing ratios. Geotechnical properties of stabilized sludge were studied. The test results revealed that the strength of stabilized sludge increased with curing time and the decrease of moisture content. Significant increases in strength were achieved to math suitability for disposal in landfills and a stabilization method was selected based on cost and availability of material. The stability of landfill slope was studied and an optimum slope ratio balancing the safety and economy was presented.

Remarks on ‘A simple decision analytic solution to the comparison of two binary diagnostic tests’ by Vickers et al.

Vickers et al make a valuable contribution to the comparison of two binary diagnostic tests by taking a decision-analytic approach [1]. They introduce relative diagnostic value which yields a threshold probability for selecting the preferred test. Two additional points are worth noting. First, although the context differs, the equation relating relative diagnostic value to the odds of prevalence and threshold odds of disease is mathematically identical to an equation for finding the optimal slope of a concave Receiver Operating Characteristic (ROC) curve when the two tests correspond to adjacent points on the ROC curve [2, 3]. The relative diagnostic value is derived by setting equal the net benefits of the two tests. The optimal slope of the concave ROC curve is found by setting equal the net benefits of tests corresponding to adjacent points on the ROC curve, which corresponds to maximizing a function by finding where its slope is zero. Second the asymptotic confidence interval for the threshold probability corresponding to the relative diagnostic value can be computed with a simple formula derived from the Multinomial-Poisson (MP) transformation [4]. The relative diagnostic value is R= n0 (c1 - b1) / {n1 (c0 - b0)}. For persons without disease, no is the total number in the sample, c0 is the number positive on the first test and negative on the second test, and b0 is the number positive on the second test and negative on the first test. For persons with disease, n1, c1, and b1 are defined analogously. Using the MP transformation applied to the logarithm of R (which may have a more symmetric distribution than R) yields, after algebraic simplification, a standard error of log(R) of selogR={−1∕n0−1∕n1+(c0+b0)∕(c0−b0)2+(c1+b1)∕(c1−b1)2}12. Let RL = exp{log(R) – 1.96 selogR} and RU = exp{log(R) + 1.96 selogR}. Let π denote the prevalence of disease. The formula for the threshold probability is p = R π / (1 + R π - π), which is denoted here by f(R, π), so the asymptotic 95% CI for p is {f(RL, π), f(RU, π)}.

Power optimization of random distributed feedback fiber lasers

We present a comprehensive study of power output characteristics of random distributed feedback Raman fiber lasers. The calculated optimal slope efficiency of the backward wave generation in the one-arm configuration is shown to be as high as ~90% for 1 W threshold. Nevertheless, in real applications a presence of a small reflection at fiber ends can appreciably deteriorate the power performance. The developed numerical model well describes the experimental data.

Estimated preejection period (PEP) based on the detection of the R-wave and dZ/dt-min peaks does not adequately reflect the actual PEP across a wide range of laboratory and ambulatory conditions

The current study evaluates the validity of the PEP computed from a fixed value for the Q-wave onset to R-wave peak (QR) interval and an R-wave peak to B-point (RB) interval that is estimated from the R-peak to dZ/dt-min peak (ISTI) interval. Ninety-one subjects participated in a 90min laboratory experiment in which a variety of often employed physical and mental stressors were presented and 31 further subjects participated in a structured 2hour ambulatory recording in which they partook in natural activities that induced large variation in posture and physical activity. PEP, QR interval, and ISTI were scored and rigorously checked by interactive inspection. Across the very diverse laboratory and ambulatory conditions the QR interval could be approximated by a fixed interval of 40ms but 95% confidence intervals were large (25.5 to 54.5ms). Multilevel analysis showed that 79% to 81% of the within and between-subject variation in the RB interval could be predicted by the ISTI with a simple linear regression equation. However, the optimal intercept and slope values in this equation varied significantly across subjects and study setting. Bland Altman plots revealed a large discrepancy between the estimated PEP using the R-wave peak and dZ/dt-min peak and the actual PEP based on the Q-wave onset and B-point. We conclude that the PEP estimated from a fixed QR interval and the ISTI could be a useful addition to the psychophysiologist's toolbox, but that it cannot replace the actual PEP to index cardiac sympathetic control.

Efficient rate control approach for JPEG2000 image coding

Abstract. JPEG2000, the new image coding standard, is more effi-cient when compared with the old JPEG standard. However, most ofthe computationsand memory usagein post-compressionrate distor-tion(PCRD)optimizationschemeinJPEG2000isredundant.Wepro-pose an efficient rate control approach for the JPEG2000 encoder. Inthis approach, optimal rate distortion (RD) slope threshold is selectedusing the minimum RD slope of lower level horizontally and verticallylow pass (LL 0 ) subband of the wavelet decomposed image. Also, thepasses of the code blocks of other subbands, whose RD slopes areless than the optimal RD slope, are skipped. The proposed approachreduces memory requirements and encoding time when comparedwith the existing rate control approaches for JPEG2000 standard,and also provides the same image quality as that of the PCRDapproach used in the JPEG2000 standard. © 2012 SPIE andIS&T. [DOI: 10.1117/1.JEI.21.3.033004] 1 IntroductionJPEG2000 is the new state-of-art image and video codingstandard. It has excellent coding performance and novel fea-tures such as superior low-bit rate compression performance,lossless and lossy compression, progressive transmission,region of interest coding, error resilience and randomcode stream access, and so on.