Semi-direct Methods Research Articles

A methodology to simulate peak water demand for water supply systems using semi-direct methods: A case study for a residential building in Mexico

Historically, approaches for determining peak water demand in buildings have been based on probabilistic methods. Extensive research has shown that these methods lack accuracy because of the human factor in the probability of use. Inaccuracy in the calculation of peak water demand is the main cause of oversized water supply systems in buildings. This has led to unfavorable effects such as: 1) increasing the building carbon footprint due to the use of more construction materials, and 2) engendering health hazards due to the stagnation of water causing microbial growing. This paper presents a step-by-step methodology that serves to calculate the peak water demand by simulating the use of plumbing fixtures based on data obtained from standardized flowrate. With the implementation of the methodology, the peak water demand estimated was 2.6 times lower in comparison to traditional methods. The main conclusion drawn from the research is the potential of the methodology to easily simulated peak water demand in residential buildings in the short term. Thus, it reveals a hotspot for peak water demand calculation and can serve as routes for future research.

Determination of Polypropylene Fiber-Reinforced Concrete Compressive Strength and Elasticity Modulus via Ultrasonic Pulse Tests

Compressive strength and elasticity modulus are the main mechanical properties of concrete. The non-destructive ultrasound pulse test can be used to determine these properties without compromising the structure’s integrity. This study seeks to assess whether a correlation exists (1) between the Reinforcement Index (RI) and the mechanical properties, (2) between the RI and the dynamic properties, and (3) among the dynamic properties of polypropylene fiber-reinforced concrete. The RI was modified through fiber volume fraction (0, 0.4, 0.8 and 1.2%) and fiber length (40, 50 and 60 mm). The dynamic properties were assessed through dynamic elasticity modulus and ultrasonic pulse velocity (UPV), which were determined by direct, semi-direct, and indirect prospect methods. Finally, compressive strength, static elasticity modulus, and Poisson’s ratio were assessed through destructive tests. Their relationship with UPV and the dynamic elasticity modulus is also subsequently studied. The results reveal a correlation between RI and compressive strength and UPV; however, the static elasticity modulus only exhibits a correlation with UPV in one of its measurement methods. Finally, empirical models were developed for predicting compressive strength, elasticity modulus as a function of ultrasonic pulse velocity and RI, and dynamic elasticity modulus as a function of compressive strength and RI.

Secondary constructions of bm$p$-ary (non-)weakly regular bent functions

Bent functions can be used in many areas, such as symmetric cryptography, sequence design, and association schemes. In this paper, a generic secondary 构造 of bent functions from indirect sum and semi-direct sum methods is presented. Our method can be used to construct high algebraic degree (non-)weakly regular bent functions by employing suitable initial (vectorial) bent functions or their combinations. More precisely, we present some classes of (weakly) regular bent functions by using vectorial $\mathcal{M}$-$\mathcal{M}$ (Maiorana-McFarland) and $\mathcal{PS}$ (partial spread) bent functions, respectively. In particular, the explicit expressions for the dual of these (weakly) regular bent functions are obtained. Based on the vectorial perfect nonlinear ($\mathrm{PN}$) functions, infinite families of non-weakly regular bent functions can also be produced.

Use Of Ultrasonic Pulse Velocity For Engineering Study Of Building Structure

ABSTRACT
 
 In accordance with the request, we have conducted field testing activities in the form of Ultrasonic pulse velocity (UPV) testing, on the building structure of the Pasar Kosambi building located in Bandung. The contents in this report are made in accordance with the standards and requirements applicable in Indonesia, and are professionally responsible for the results of consulting services provided in accordance with the provisions and the applicable professional code of conduct. This inspection and testing activity aims to ensure the Kosambi Market Building is in good condition after experiencing a fire for almost 40 hours on the semi basement floor on May 18, 2019. So that, after the testing process is carried out and the analysis can be functioned properly and safely according to the market business plan boarding house. UPV testing to determine the density of concrete was taken at the Pasar Kosambi Bandung building with a total test location of 25 points. Concrete density testing was carried out on Columns, Beams and Floor Slabs using the Direct and Semi-Direct methods. Based on the integrity of the concrete density (Ultrasonic Pulse Velocity), the test results show the level of concrete density which is in the bad category with a propagation value of 2.4 km / sec (20.4 Mpa or 240.9 kg / cm2) to the very good category with a propagation value of 4.6 km / sec (45.2 MPa or 533.7 kg / cm2).
 
 Keywords: Ultasonic Pulse Velocity, Concrete Density

Bioleaching of Indonesian Galena Concentrate With an Iron- and Sulfur-Oxidizing Mixotrophic Bacterium at Room Temperature.

Biohydrometallurgy is believed to be a promising future study field for the recovery of lead (Pb) from ores/concentrates since the pyrometallurgical/hydrometallurgical processes have been largely applied to recover Pb to date, which operates at high temperature and generates volatile Pb matters that are hazardous and carcinogenic to human health. Hence, the main purpose of this study was to investigate the biohydrometallurgical extraction of Pb from the Indonesian galena concentrate through bioleaching using an iron- and sulfur-oxidizing mixotrophic bacterium (identified as Citrobacter sp.). The bioleaching experiments were conducted in shake flasks containing the modified LB broth medium supplemented with galena concentrate with a particle size of d80 = 75 μm at room temperature. Both semi-direct and direct bioleaching methods were employed in this study. The bacterium was able to extract lead (Pb) from galena concentrate with high selectivity to Cu and Zn (0.99 and 0.86, respectively). The highest extraction level of 90 g lead dissolved/kg galena concentrate was achieved using direct bioleaching method at bioleaching conditions of 2% w/v pulp density, 5 g/L FeCl3, 50 g/L NaCl, 20 g/L molasses and a rotation speed of 180 rpm at room temperature (25°C). The addition of FeCl3, NaCl, and molasses increased the lead leaching efficiencies, which were also evidenced by the FTIR, XRD, and SEM-EDS analyses. From industrial and commercial standpoints, the selective bioleaching represented in this study may be beneficial to the development of lead leaching from sulfide minerals, since insoluble anglesite (PbSO4) precipitates are formed during ferric sulfate oxidation, thus making the recovery of lead through bioleaching unpractical.

Explicit Iterative Methods of Second Order and Approximate Inverse Preconditioners for Solving Complex Computational Problems

Explicit Exact and Approximate Inverse Preconditioners for solving complex linear systems are introduced. A class of general iterative methods of second order is presented and the selection of iterative parameters is discussed. The second order iterative methods behave quite similar to first order methods and the development of efficient preconditioners for solving the original linear system is a decisive factor for making the second order iterative methods superior to the first order iterative methods. Adaptive preconditioned Conjugate Gradient methods using explicit approximate preconditioners for solving efficiently large sparse systems of algebraic equations are also presented. The generalized Approximate Inverse Matrix techniques can be efficiently used in conjunction with explicit iterative schemes leading to effective composite semi-direct solution methods for solving large linear systems of algebraic equations.

단일 셀에서 소수다공성 멤브레인의 증발냉각 방법별 성능 비교에 대한 실험적 연구

단일 셀에서 소수다공성 멤브레인의 증발냉각 방법별 성능 비교에 대한 실험적 연구

Correlation of reinforcement concrete quality based on variations in UPV testing methods

Ultrasonic Pulse Velocity (UPV) test includes a simple Non Destruction Test (NDT) testing method, by utilizing ultrasonic waves. In the implementation of UPV testing with direct, semi-direct, and indirect methods give a quick result of different pulse velocity, with the same quality of concrete. Therefore, this study was conducted to get the correlation and correction value of all three testing methods with PUNDIT Lab+ tool on reinforced concrete. The study used a speciment of concrete beams 15x15x60 cm3 with concrete quality K-275, K-250, K-225 each as much as 3 specimen. The average value of the measurement result with the direct UPV method is 12%, 7% and 5% less than the average value of the semi-direct method of UPV direction vertically, the semi-direct method of the UPV direction horizontally, and the indirect method UPV. Conversion of the measurement results for the direct UPV method of the semi-direct UPV vertical direction, semi-direct UPV direction horizontal and indirect UPV can use the regression equation Vd = 0.2462 Vsd-v + 3192, Vd = 0.1073 Vsd-h + 3923.8 and Vd = 0.0195 Vin + 4341.8.

Pengaruh Variasi Mutu Beton Pada Benda Uji Balok Normal Dengan Menggunakan Metode Non Destructive Test

This research aims to know the relationship of the pulse velocity to compression strength with a variation of the quality of the concrete based on the ultrasonic pulse velocity. This research uses the PUNDIT PL-200 to do the process of analysis of concrete density based on the pulse velocity from the UPV. From UPV testing in this research showed that each quality and each method has a strong connection of the same compression strength and velocity. This is indicated by rising the velocity graph as the quality of the concrete itself increases. From this research also gained comparisons between the three methods, which is between direct and semi-direct methods, direct and indirect methods, as well as semi-direct and indirect methods.

Improving efficiency of semi‐direct møller–plesset second‐order perturbation methods through oversubscription on multiple nodes

The purpose of this work is to evaluate the efficacy of oversubscription, at the 1n, 2n, and 3n levels for n physical cores, on semi-direct MP2 methods within NWChem when using two and three Intel nodes. Semi-direct MP2 energy and gradient calculations were performed on chemical systems ranging from 824 to 1626 basis functions using the cc-pVDZ basis set. Wall times for semi-direct MP2 energies were reduced by as much as 36% using two nodes and 44% using three nodes compared to no oversubscription. Total energy consumed by the CPU and DRAM was also reduced by as much as 12% using two nodes and as much as 20% using three nodes when oversubscribing. MP2 gradient wall times improved by as much as 16% using two nodes and 18% using three nodes compared to execution at the 1n level; however, energy savings were insignificant. Intel performance-counter data show a strong correlation between total wall time saved and less time spent in the idle state, indicating a more efficient use of the processors when oversubscribing. © 2019 Wiley Periodicals, Inc.

SDVL: Efficient and Accurate Semi-Direct Visual Localization.

Visual Simultaneous Localization and Mapping (SLAM) approaches have achieved a major breakthrough in recent years. This paper presents a new monocular visual odometry algorithm able to localize in 3D a robot or a camera inside an unknown environment in real time, even on slow processors such as those used in unmanned aerial vehicles (UAVs) or cell phones. The so-called semi-direct visual localization (SDVL) approach is focused on localization accuracy and uses semi-direct methods to increase feature-matching efficiency. It uses inverse-depth 3D point parameterization. The tracking thread includes a motion model, direct image alignment, and optimized feature matching. Additionally, an outlier rejection mechanism (ORM) has been implemented to rule out misplaced features, improving accuracy especially in partially dynamic environments. A relocalization module is also included but keeping the real-time operation. The mapping thread performs an automatic map initialization with homography, a sampled integration of new points and a selective map optimization. The proposed algorithm was experimentally tested with international datasets and compared to state-of-the-art algorithms.

Challenges in Monocular Visual Odometry: Photometric Calibration, Motion Bias, and Rolling Shutter Effect

Monocular visual odometry (VO) and simultaneous localization and mapping (SLAM) have seen tremendous improvements in accuracy, robustness and efficiency, and have gained increasing popularity over recent years. Nevertheless, not so many discussions have been carried out to reveal the influences of three very influential yet easily overlooked aspects: photometric calibration, motion bias and rolling shutter effect. In this work, we evaluate these three aspects quantitatively on the state of the art of direct, feature-based and semi-direct methods, providing the community with useful practical knowledge both for better applying existing methods and developing new algorithms of VO and SLAM. Conclusions (some of which are counter-intuitive) are drawn with both technical and empirical analyses to all of our experiments. Possible improvements on existing methods are directed or proposed, such as a sub-pixel accuracy refinement of ORB-SLAM which boosts its performance.

Leaf area index estimated by direct, semi-direct, and indirect methods in European beech and sycamore maple stands

Leaf area index (LAI) is one of the most important characteristics of forest stands that affects the fundamentals of tree physiological processes, biomass production, and mechanical stability. The LAI results obtained by the semi-direct and indirect methods (the needle technique and an LAI-2000 PCA) in three European beech (Fagus sylvatica L.) stands and one sycamore maple (Acer pseudoplatanus L.) stand were compared with LAI estimated by litter traps during the 2013 growing season. Seasonal LAI was estimated using an LAI-2000 PCA which showed similar trends among the stands and strongly corresponded to phenological phases of deciduous stands in Europe, with the fastest rate of leaf area increment occurring during the first month following bud break. During the growing season, maximum stand LAI value was on June 19th and reached 4.5–5.1, and 4.0 in the beech and maple stands, respectively. The needle technique significantly underestimated (p .05) LAI on average by 15.1% and 5.8% in the beech and maple stands, respectively. All methods for LAI estimation at the stand level could be applicable in deciduous forest stands (beech, maple) with similar site and stand characteristics. However, calibration by direct method is necessary to obtain the required precision.

First evaluation of semidirect recycling methods for the reclamation of cemented carbides based on a literature survey

At the moment the industrially applied techniques for cemented carbide reclamation feature several deficiencies. Depending on the process route, obstacles consist in high energy and chemical consumption (indirect recycling methods) or a deterioration of the recycled product in comparison with the primary material (direct recycling approach). Therefore, an alternative middle course provided by semidirect recycling processes seems promising. Accordingly, the coating materials as well as the binder metals are leached off the substrate keeping the hard phase unaffected and ready for reuse. However, the literature reports various difficulties like the slow dissolution of the binder, particularly if the scrap consists of larger pieces, contains a low binder metal perecentage or a small grain size. Furthermore, oxidation of the cemented tungsten occurs as an undesired reaction, causing even slower lixiviation and a contamination of the recycled product. Due the fact of an inexistent comparable systematic analysis of the semidirect recycling procedures, this article deals with a primary screening of potential combinations of acids, additives and oxidizing agents found in a literature survey. All experiments took place under the same conditions in a temperature controlled double-walled reaction vessel, varying only the molar concentrations of the different species as used in literature. A crucial point comprised of the development of an appropriate sample preparation, which allowed a simplification of the analysis along with its applicability in future kinetic investigations of selected solutions. As a result, promising combinations of chemicals are ready for further investigations determined by penetration depth and abrasion of the hard metal substrate. Successfully applied mixtures incorporate acids such as HNO3 and HCl followed by some organic acids, all combined with H2O2 as oxidant. Keywords: semidirect hard metal recycling, reclamation of cemented carbides, leaching of cobalt

Study to detect bond degradation in reinforced concrete beams using ultrasonic pulse velocity test method

Concrete technologists have used ultrasonic pulse velocity test for decades to evaluate the properties of concrete. However, the presented research work focuses on the use of ultrasonic pulse velocity test to study the degradation in steelconcrete bond subjected to increasing loading. A detailed experimental investigation was conducted by testing five identical beam specimens under increasing loading. The loading was increased from zero till failure in equal increments. From the experimentation, it was found that as the reinforced concrete beams were stressed from control unloaded condition till complete failure, the propagating ultrasonic wave velocity reduced. This reduction in wave velocity is attributed to the initiation, development, and propagation of internal cracking in the concrete surrounding the steel reinforcement. Using both direct and semidirect methods of testing, results of reduction in wave velocity with evidence of internal cracking at steel-concrete interface are presented. From the presented results and discussion, it can be concluded that the UPV test method can be successfully employed to identify zones of poor bonding along the length of reinforced concrete beam. The information gathered by such testing can be used by engineers for localizing repairs thereby leading to saving of time, labor and cost of repairs. Furthermore, the implementation strategy along with real-world challenges associated with the application of the proposed technique and area of future development have also been presented.

12. DISCOURSE AND ASSESSMENT

Many contemporary currents in applied linguistics have favored discourse studies within assessment; there have been calls for cross-fertilization with other areas within applied linguistics, critiques of the positivist tradition within language testing research, and the growing impact of Conversation Analysis (CA) and sociocultural theory. This chapter focuses on the resulting increase in discourse-based studies of oral proficiency assessment techniques. These studies initially focused on the traditional oral proficiency interview but have since been extended to new test formats, including paired and group interaction. We discuss the research carried out on a number of factors in the assessment setting, including the roles of interlocutor, candidate, and rater, and the impact of tasks, task performance conditions, and rating criteria. Recent research has also concentrated more specifically on the assessment of pragmatic competence and on the applications of technology within the assessment of spoken language, including the comparability of semidirect and direct methods for such assessment and the use of computer corpora.

Quasidegenerate second-order perturbation corrections to single-excitation configuration interaction

A family of quasidegenerate second-order perturbation theories that correct excitation energies from single-excitation configuration interaction (CIS) are introduced which generalize the earlier non-degenerate second-order method, CIS(D). The new methods are termed CIS(Dn), where n ranges from 0 to ∞, according to the number of terms retained in a doubles denominator expansion. Truncation at either n = 0 or n = 1 yields methods which involve the diagonalization of a dressed singles-only response matrix, where the dressing is state-independent. Hence CIS(D0) and CIS(D1) can be implemented efficiently using semidirect methods, which are discussed. Test calculations on formaldehyde, ethylene, chlorine nitrate, styrene, benzaldehyde, and chalcone are presented to assess the performance of these methods. CIS(D0) and CIS(D1) both show significant improvements relative to CIS(D) in cases of near-degeneracy.

Preconditioned iterative methods for solving 3d boundary value problems

A new class of approximate LU-type factorization procedures for solving sparse linear systems of irregular structure, which are derived from the finite element method of Partial Differential Equations in three space variables, is introduced. Theoretical results on the convergence rate of approximate matrix factorization semi-direct methods for three space variables are introduced. Applications of the method on a three dimensional linear boundary value problem is discussed and numerical results are given

On Poisson solvers and semi-direct methods for computing area based optical flow

Simchony, Chellappa, and Shao (1990) proposed a semi-direct method for computing area based optical flow. Their method is based on the iterative application of a direct Poisson solver. This method is restricted to Dirichlet boundary conditions, i.e., it is applicable only when velocity vectors at the boundary of the domain are known a priori. The authors show, both experimentally and through analysis, that the semi-direct method converges only for very large smoothness. At such levels of smoothness, the solution is obtained merely by filling in the known boundary values; the data from the image is almost totally ignored. Next, the authors consider the Concus and Golub method (1973), another semi-direct method, for computing optical flow. This method always converges, but the convergence is too slow to be of any practical value. The authors conclude that semi-direct methods are not suited for the computation of area based optical flow.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Semi-direct algorithms for the MP2 energy and gradient

The cost (via the number of two-electron integral evaluations) and the maximum size of a direct second-order Møoller-Plesset (MP2) energy or gradient calculation are both determined by the available computer memory. Therefore we formulate semi-direct MP2 methods that utilize disk space (which is usually much larger than memory size) for the steps that require most storage. In terms of the molecular basis set size, they require as little as quadratic memory and cubic disk. The amount of input/output transfer between memory and disk is quartic plus the cost of transpositions, which is between quartic and quintic. A variety of calculations are presented comparing the fully direct, semi-direct and conventional algorithms. The semi-direct methods are shown to be superior to conventional algorithms despite requiring less disk space, and are also often preferred over the direct methods.