Horizontal Partition Research Articles

Weakly Nonlinear Convection in a Porous Layer with Multiple Horizontal Partitions

We consider convection in a horizontally uniform fluid-saturated porous layer which is heated from below and which is split into a number of identical sublayers by impermeable and infinitesimally thin horizontal partitions. Rees and Genc (Int J Heat Mass Transfer 54:3081–3089, 2010) determined the onset criterion by means of a detailed analytical and numerical study of the corresponding dispersion relation and showed that this layered system behaves like the single-sublayer constant-heat-flux Darcy–Benard problem when the number of sublayers becomes large. The aim of the present work is to use a weakly nonlinear analysis to determine whether the layered system also shares the property of the single-sublayer constant-heat-flux Darcy–Benard problem by having square cells, as opposed to rolls, as the preferred planform for convection.

Optimal Positioning of Strips for Heat Transfer Reduction within an Enclosure

Heat transfer reduction capabilities of a vertical or a horizontal adiabatic partial partition fixed in a differentially heated cavity with insulated top and bottom walls are analyzed and compared. The effects of length and location of the partition is taken into account for aspect ratios from 1 to 4 and for Rayleigh numbers from 103 to 106. Different characteristics of square and higher aspect ratio cavities are compared and a comprehensive correlation of the heat transfer reduction is introduced, incorporating all the pertinent parameters. Based on our results, vertical baffles more efficiently reduce heat transfer, in most cases.

Overall Assessment of Indoor Conditions in a School Building: an Italian Case Study

Current standards for indoor comfort are based on studies of adults, but they also apply tochildren, even though children differ in terms of metabolic rates, clothing types, activity levels, and preferences in space arrangement. Children are also more sensitive to a range of environmental factors, they are usually unable to interact with their environment, and they accept indoor conditions passively. This study aims to extend research into indoor environmental quality (IEQ) for children by providing analysis, measurements and surveys carried out in an Italian primary school. Continuous monitoring was combined with a detailed spot monitoring campaign, during which pupils completed a questionnaire so that subjective and objective evaluations could be compared. Thermal comfort was also evaluated by comparing pupils’ sensations based on the two most common approaches: the heat balance and adaptive comfort models. Tests revealed that there was no clear, uniform correspondence between subjective response and acoustic and thermal measurements. Children reacted actively to discomfort, suggesting that they should be allowed to interact with their environment. Building acoustics were also measured in order to evaluate the insulating properties of building elements. The following tests were conducted: facade sound insulation, sound insulation of the vertical and horizontal partitions between classrooms, and the impact levels between overlapped classrooms. Reverberation time and background noise were measured in unoccupied, furnished classrooms after school hours. Impulse response and Speech Transmission Index (STI) measurements were also performed in one classroom.

Nano Magnetic STT-Logic Partitioning for Optimum Performance

Magnetoresistive RAMs (MRAMs) are the new generation of nonvolatile memories that use magnetic tunnel junctions (MTJs) to store bit information. Horizontal (bit and source) and vertical (word) lines partition the MRAM into a 2-D grid similar to a conventional memory. This paper relies on a logic-in-memory architecture where MRAM cells are placed in close proximity so that they can behave both as logic elements and as memory bits. When the clock signal is active the cells compute logic, while at other times the cells store the data in them and behave as memory. Using these MRAM cells, in this paper, we have designed two fundamental components in datapath and logic circuits, the XOR and majority. By transferring logic responsibilities between the metal lines, CMOS peripherals and the MTJs, we have achieved a significant reduction in MTJ cell count, energy, and delay over previous designs. For example, an energy savings of more than 75% and a cell reduction of more than 81.25% are obtained for a 2-input XOR in standalone mode of operation. Though this hybrid sharing of responsibilities between the MTJs and CMOS has apparently increased the overhead on CMOS, it has however reduced the net power consumption in the CMOS peripherals. This happens because the CMOS now has a fewer number of cells to control. The reduction in the CMOS power varies from close to 50% for a 2-input XOR to greater than 10% for a majority. In addition, the designs also obey the rules of hierarchical modeling which helped us to use the novel 2-input XORs as bricks for designing the novel 3-input XOR. Again a 3-input XOR and majority are used to custom develop a one-bit full adder. Together with an inter-cell spacing of 20 nm and low power spin transfer torque current-driven write and clock operations, the novel designs presented in this paper has the potential to target the low energy and high density logic-in-memory applications.

CFD ANALYSIS OF FLOW THROUGH HORIZONTAL CEILING OPENING DUE TO BUOYANCY AND PRESSURE DIFFERENCE

The buoyancy driven exchange flow through the large openings in horizontal partitions occurs in many practical situations such as in enclosed regions with a ceiling opening and a heat source such as fire. The density difference between two compartments arises partly due to difference in composition and partly from the difference in temperature. A heavier fluid located on the top of a lighter fluid and separated by a horizontal vent constitutes a gravitationally unstable system. Horizontal vents produce flow, which are unstable with irregular oscillatory behavior. However, when lower compartment is slightly pressurized the flow becomes stable and unidirectional. A numerical study has been performed to characterize the bi-directional flow and transition to unidirectional flow through a horizontal vent in an enclosure, due to differences in pressure and density across the vent. Fresh and salt water has been considered as working fluids to create density difference across the vent with a pressure field imposed in the lower compartment. The pressure in the lower region was increased to find the critical pressure corresponding to transition to unidirectional from bi-directional flow. Unsteady, 2D axisymmetric, incompressible Navier–Stokes equation along with species, turbulence and continuity equation have been solved with finite volume method using the in-house computational fluid dynamics (CFD) code. Several cases were examined to compute the critical pressure for various density differences for low opening aspect ratio. The code has been validated with reported experiments and used to simulate various other practical cases occurred during fire induced flow through such openings.

The onset of convection in a porous layer with multiple horizontal solid partitions

The principal objective of the present paper is to investigate the onset of convection in a horizontal layer heated from below which consists of distinct porous sublayers which are separated by solid heat-conducting partitions. Each of the porous sublayers are identical as are the solid partitions. The present analysis employs linearised stability theory and a dispersion relation is derived from which neutral curves may be computed. For two-layer configurations the dispersion relation may be written explicitly, but for larger numbers of sublayers a simple systematic numerical procedure is used to compute the dispersion relation which, while it may also be written analytically, rapidly becomes increasingly lengthy as the number of sublayers increases. It is found that neutral curves are always unimodal and each has a well-defined single minimum. We attempt to give a comprehensive physical understanding of the effect of the number of layer, the relative thickness of the partitions and the conductivity ratio on the onset of convection and the form taken by the onset modes. Our results are compared with those of Rees and Genç (2011) [1] who considered the special case where the partitions are infinitesimally thin.

Hydrodynamics and spatial zonation of the Capo Peloro coastal system (Sicily) through 3-D numerical modeling

Since advection and diffusion are the main physical processes that influence the cleaning capacity of coastal transitional waters, the 3-D spatial distribution of the water renewal times was used to delineate a physically-based zonation scheme. The temporal and spatial variations of the hydrodynamics are assessed using a validated three dimensional hydrodynamic finite element model. The developed methodology was applied to the Cape Peloro system, a coastal protected area located in the Messina Strait (Italy) consisting of two connected small brackish basins: the shallow Lake Ganzirri and the deep meromictic Lake Faro. The hydrodynamics of the two coastal lakes shows strong seasonal and spatial variation. The 3-D distribution of the water renewal times suggests a horizontal partition of the Lake Ganzirri into two sub-basins and a vertical zonation of the Lake Faro, with the mixolimnion extending till 10m depth and the presence of a persistent bottom stagnant layer. The derived physically-based zonation scheme helps in explaining the highly heterogeneous spatial distribution of many biogeochemical variables in the Cape Peloro coastal system.

Distributed RK- Secure Sum Protocol for Privacy Preserving

Secure multi party computation allows several parties to compute some function of their inputs without disclosing the actual input to one another. Secure sum computation is an easily understood example and the component of the various secure multi party computation solutions. Secure sum computation allows parties to compute the sum of their individual inputs without disclosing the inputs to one another. In this paper, we propose a protocol with more security, when a group of the computing parties want to know the data of some other party. I. INTRODUCTION The huge growth of the Internet and its easy access by common man created opportunities for joint computations by multiple parties. All the participating parties for the sake of their mutual benefit want to compute the common function of their inputs but at the same time they are worried about the privacy of their data. This subject of the information security is called secure multi party computation. This subject has two goals; one is the privacy of the individual data inputs and another is the correctness of the result. Mainly two models exist in the literature for the analysis of the secure multi party computation problems. Ideal model of the secure multi party computation uses a Trusted Third Party apart from the participating parties. Parties supply their inputs to the Trusted Third Party. Computation of the function is done by the Trusted Third Party and then the result is sent to all the parties. In this paradigm the trustworthiness of the Trusted Third Party is critically important because if the Trusted Third Party turns corrupt, it can supply the private inputs of one party to others. But it is extensively used model of the secure multi party computation due to its easy implementation and the protocols available which prevent the Trusted Third Party to act maliciously. Real model of the secure multi party computation does not use any Trusted Third Party but the parties themselves agree on some protocol for the computation. The parties behavior in the secure multi party computation is important to consider. An honest party follows the protocol and respects the privacy of other parties. A semi honest party follows the protocol but also tries to learn other information than the result. The corrupt party neither follows the protocol nor respects the privacy of other parties. Different protocols are needed for different secure multi party computation models and the behavior of the party. Solutions are available for secure multi party computation problems using cryptographic techniques, randomization techniques and anonymization methods. The subject of secure multi party computation has been evolved from two party comparison problems (1) to multiparty image template matching problems. Many specific secure multi party computation problems have been defined and analyzed by researchers like Private Information Retrieval, Selective Function Evaluation, Privacy-Preserving Database Query, Privacy-Preserving Geometric Computation, Privacy- Preserving Statistical Analysis, Privacy-Preserving Intrusion Detection and Privacy-Preserving Cooperative Scientific Computation. Based on these general secure multi party computation problems many real life applications have been emerged like Privacy- Preserving Electronic Voting, Privacy-Preserving Bidding and Auctions, Privacy-Preserving Social Network Analysis, Privacy-Preserving Signature and Face Detection, Etc. Secure sum computation problem of secure multi party computation can be defined as: How multiple parties can compute the sum of their input values without disclosing actual values to one another. Secure sum can work as the tool for the secure multi party computation solutions in the privacy preserving distributed data mining problems (2). We proposed a secure sum protocol using random numbers (2). In this paper, we proposed a novel changing neighbors approach Distributed RK secure sum protocol for achieving more security in case a group of the parties collude to know the private data of some other party. 1.1 Distributed Database Partition: - Database is divided into three main portioning horizontal partition, vertical partition and hybrid partition. 1.1.1 Horizontal Partitioning: - Horizontal partitioning divides the whole database into the number of small database according to the row splitting. So that the execution of query will be very fast as well as we will be able to provide more privacy to the portioned database.

Effect of the opening aspect ratio on a buoyant pulsating exchange flow through a circular ceiling opening in a horizontal partition

An interesting transport phenomenon is observed through openings between two compartments separated by a thin, vented, horizontal partition such as those between containment areas in nuclear power systems, in other installations in the event of fire, passive cooling of heated structures, and in natural building ventilation. A heavier fluid located on the top of a lighter fluid and separated by a horizontal vent constitutes a gravitationally unstable system. Horizontal vents produce flow, which are unstable with irregular oscillatory behavior. The objective of the present work was to simulate such type of flow across a circular opening in a horizontal partition in the presence of a buoyancy force. Unsteady, axisymmetric Navier–Stokes equations were solved using the in-house CFD code based upon the well-established finite volume methodology. In terms of temporal differencing a second-order accurate Crank–Nicolson scheme was used. Interpolation to cell faces for the convective terms was performed using a third-order QUICK scheme and a second-order central differencing was used for the viscous terms. Pressure-velocity coupling was based on the SIMPLE procedure. The upper chamber was filled with salt water and the lower chamber with fresh water, creating a density differential between the two chambers. Opposing forces at the interface created a gravitationally unstable system, and an oscillating exchange of fluid developed. Several cases were numerically simulated and classified with respect to an aspect ratio L/D, where L represents the thickness of the partition and D represents the diameter of the opening in the partition. The flow coefficients and pulsation frequency have been determined. The effect of opening aspect ratio on frequency and flow coefficient was observed. © 2012 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com/journal/htj). DOI 10.1002/htj.21023

Scene classification using a multi-resolution bag-of-features model

This paper presents a simple but effective scene classification approach based on the incorporation of a multi-resolution representation into a bag-of-features model. In the proposed approach, we construct multiple resolution images and extract local features from all the resolution images with dense regions. We then quantize these extracted features into a visual codebook using the k-means clustering method. To incorporate spatial information, two modalities of horizontal and vertical partitions are adopted to partition all resolution images into sub-regions with different scales. Each sub-region is then represented as a histogram of codeword occurrences by mapping the local features to the codebook. The proposed approach is evaluated over five commonly used data sets including indoor scenes, outdoor scenes, and sports events. The experimental results show that the proposed approach performs competitively against previous methods across all data sets. Furthermore, for the 8 scenes, 13 scenes, 67 indoor scenes, and 8 sport events data sets, the proposed approach outperforms state-of-the-art methods.

Privacy Preserving Combinatorial Function for Multi-Partitioned Data Sets

preserve the electronic fitness records of data mining applications, Data perturbation is used. It is a form of privacy- preserving data mining. An improved amount and range of information stored in databases has direct to an enhancement in the desire for ranked and best match queries. Such queries are mainly applicable when dealing with privacy- sensitive information. To facilitate privacy preservation in data mining or machine learning algorithms over horizontally partitioned or vertically partitioned data, many protocols have been proposed using SMC and various secure building blocks. In this work, we plan to present an effective and efficient cluster based privacy preserving data perturbation technique to mine Multi-partitioned data sets that comprises of both vertical and horizontal data sets which is current demand of e- business and e-commerce data mining environment. To evaluate a trade of between data privacy and transparency of individual's data, data perturbation technique is presented with validation and authentication. In multi-partitioned data distribution, data perturbation raised ambiguity between vertical and horizontal partitions of the data. To overcome the ambiguity, we plan to introduce divisive k-neighbor clusters for multi-partitioned data sets. The performance is evaluated with bench data sets obtained from popular e-business / e- commerce sites. (Amazon, e-bay etc.,). Keywords-partitioned data sets, Privacy preservation, Data perturbation technique.

Effect of a Partition on Hydro-Magnetic Convection in an Enclosure

We deal with the effect of an adiabatic partition and magnetic field on magneto-hydrodynamic natural convection flow and heat transfer in a partitioned enclosure. The horizontal walls of the enclosure are adiabatic and the vertical walls are isothermal. The adiabatic partition is attached to either the bottom adiabatic wall or hot isothermal wall of the enclosure. The governing equations are discretized by the finite-volume method and are solved by iteration. We discuss transient and steady-state cases for different combinations of parameters in the study. The results are obtained for different values of the Hartmann, Grashof and Prandtl numbers and different positions of the partition, and presented graphically. The heat transfer and fluid flow characteristics inside the enclosure are affected by the partition and magnetic field. We find that the heat transfer rate is enhanced when the partition is attached to the adiabatic wall. The heat transfer rate is suppressed when the Hartmann number is increased. In the presence of the magnetic force, the heat transfer rate is increased by 1 and 2% when the Prandtl number is increased from 0.015 to 0.054 for the vertical and horizontal partition cases, respectively.

ERA

The suffix tree is a data structure for indexing strings. It is used in a variety of applications such as bioinformatics, time series analysis, clustering, text editing and data compression. However, when the string and the resulting suffix tree are too large to fit into the main memory, most existing construction algorithms become very inefficient. This paper presents a disk-based suffix tree construction method, called Elastic Range (ERa), which works efficiently with very long strings that are much larger than the available memory. ERa partitions the tree construction process horizontally and vertically and minimizes I/Os by dynamically adjusting the horizontal partitions independently for each vertical partition, based on the evolving shape of the tree and the available memory. Where appropriate, ERa also groups vertical partitions together to amortize the I/O cost. We developed a serial version; a parallel version for shared-memory and shared-disk multi-core systems; and a parallel version for shared-nothing architectures. ERa indexes the entire human genome in 19 minutes on an ordinary desktop computer. For comparison, the fastest existing method needs 15 minutes using 1024 CPUs on an IBM BlueGene supercomputer.

Special issue on business process lifecycle: design, deployment, operation and evaluation

Keywords: Business Process ; Lifecycle ; Deployment Reference EPFL-ARTICLE-176301doi:10.1002/smr.559View record in Web of Science Record created on 2012-04-19, modified on 2017-05-12

Flowrates of condensate through the annular gaps in the partitions used in steam-water heaters

We present the results obtained from experiments on determining condensate flowrate through the annular gaps at locations in which heat-transfer tubes pass through the holes in the horizontal spacer partitions used in vertical steam-water heaters. Expressions for calculating the coefficient of pressure drop due to friction λfr = f(Re) in real gaps are proposed on the basis of the obtained data.

The onset of convection in porous layers with multiple horizontal partitions

In this paper we investigate the onset of convection in a horizontally partitioned porous layer which is heated from below. Identical sublayers are separated by thin impermeable barriers. A linear stability analysis is performed, and dispersion relations are obtained directly and explicitly for two- and three-layer configurations. A systematic numerical procedure is devised to compute the dispersion relation for an arbitrary number of sublayers, but from this it is possible to guess the correct analytical form of the dispersion relation for general cases. Neutral stability curves are found to organise themselves into natural groups of N members when there are N sublayers. When the disturbance wavenumber, k, is large, each member of any group lies within an O( k −1) distance of all other members, but within an O(1) distance of other groups. When the number of sublayers is large, the system tends towards one with a critical Darcy–Rayleigh number of 12 and a critical wavenumber of zero; this is the well-known property of a single porous layer with constant heat flux boundary conditions. An asymptotic analysis is performed in order explore these two apparently disparate configurations. Finally, another asymptotic analysis is used to determine the critical Rayleigh number and its associated wavenumber when the number of sublayers is large.

Privacy Preserving Clustering for Distributed Homogeneous Gene Expression Data Sets

In this paper, the authors present a new approach to perform principal component analysis (PCA)-based gene clustering on genomic data distributed in multiple sites (horizontal partitions) with privacy protection. This approach allows data providers to collaborate together to identify gene profiles from a global viewpoint, and at the same time, protect the sensitive genomic data from possible privacy leaks. The authors developed a framework for privacy preserving PCA-based gene clustering, which includes two types of participants such as data providers and a trusted central site. Within this mechanism, distributed horizontal partitions of genomic data can be globally clustered with privacy preservation. Compared to results from centralized scenarios, the result generated from distributed partitions achieves 100% accuracy by using this approach. An experiment on a real genomic data set is conducted, and result shows that the proposed framework produces exactly the same cluster formation as that from the centralized data set.

Transient Flow of Air through Rectangular Vents in a Horizontal Partition

Transient laminar flow of air through rectangular vents in a horizontal partition between two large chambers was investigated. For vent aspect ratios of 1, 0.5, and 2, three flow regimes were identified as the Rayleigh number (Ra) was varied from 1 × 103 to 5 × 104 based on flow parameters in the vent and the corresponding modes of heat transfer through it. The critical control parameter was found to be the Rayleigh number, which determined the flow regimes of conduction, counter current, and oscillatory flow regimes. As the effective driving potential decreased with time, flow changed from one regime to the other such that higher Rayleigh number results showed all the three regimes over time. The circulation patterns within the vent for conduction regime (Ra < 1500) appeared to follow Chandrasekhar's (1961) well-known linear stability results. The flow exchange increases with partition thickness L/D = 0.5 and decreases for L/D = 2. At higher Ra, sudden bursts of upflow with a corresponding downflow were documented and compared with experimental observations in the literature. The time traces of velocity and temperature fields for this flow regime reveal interesting mechanisms, which have been explained.

Numerical Study of Natural Convection Heat Transfer of Porous Cavity contains Partitions and Square body by Using Thermal Non-Equilibrium Model

In this research, natural cnvective heat transfer between hot walls of cavity and a cold body with square section concentric in cavity is studied numerically. The cavity is filled with a saturated porous medium with thermally non-equilibrium between the solid and fluid phases. Two adiabatic partitions attached to the walls of cavity .The governing equations include continuity, momentum and energy equations are solved by using finite deference method with Gauss-Seidle iterative method. This investigation was performed under the effect of four non-dimensional groups which defined as : modified Rayleigh number (100≤Ra*≤1000), scaled heat transfer coefficient (0.1≤H≤100), thermal conductivity ratio (0.1≤Kr≤100) and the location of the partitions with respect to the length of the cavity (Yp*=0.25,0.5,0.75). The results were presented in terms of streamlines and isotherms of fluid and solid phases and the relations between Nusselt number variation with modified Rayleigh number .The Nusselt number in each phases(solid and liquid) and total Nusselt number are found to be increased proportionally due to the increasing in modified Rayleigh number. The effect of thermal conductivity ratio on Nusselt number was comprehensive while scaled heat transfer coefficient was confined to solid phase Nusselt number. Also the results showed that when the two partitions moved towards upper part of cavity , the quantity of heat transfer is to be larger and the maximum heat transfer is to be when the horizontal partitions in the upper part of the cavity in all cases .

Estudo da energética modal para episódios de ZCAS. Parte I: análise observacional

As trocas horizontais e verticais de energia para um composto de sete episódios de Zona de Convergência do Atlântico Sul (ZCAS), foram estudadas a partir da decomposição em modos normais, considerando-se a partição vertical de energia entre os modos externo e internos, e as interferências entre os modos horizontais de oscilação Rossby, Kelvin, Misto Rossby-Gravidade, Gravidade Oeste e Leste. Um máximo de porcentagem de energia total (aproximadamente 60%) é observado para os modos internos 4 a 7, com alturas equivalentes entre 100 e 600 metros, especialmente sobre grande parte da América do Sul central e próximo ao equador, incluindo a região da ZCAS. À medida que a latitude aumenta, a energia é distribuída para os modos mais externos (n=1 a 3). Para a partição horizontal de energia, as maiores contribuições foram obtidas para as auto-interações dos modos Rossby e Kelvin e interações cruzadas Rossby-Kelvin, em todas as categorias de modos verticais, sendo estas últimas responsáveis pelas interferências construtivas de energia na região da ZCAS. As interações entre modos verticais mostraram um aumento da porcentagem de energia dos Baixos Níveis para a Estratosfera, com máxima interferência positiva (negativa) de energia em Altos Níveis (Estratosfera), para os modos internos 4 a 7.