Entry Width Research Articles

Flexible Packet Matching with Single Double Cuckoo Hash

In modern switches, a packet can go through a number of processing steps to determine, for example, if the packet has to be discarded due to security policies, if it needs to be marked for quality of service or to determine the next hop for the packet. Most of those steps can be modeled as a matching of some of the packet fields with a set of rules that are stored in the switch. This has been generalized with the adoption of Software Defined Networks, using for example, the Openflow protocol, on which the processing steps are programmable as table matching operations and defined dynamically by a controller. Implementing this flexible packet matching in a switch is challenging, as we need to support multiple matching tables, each having different key size, and the size of the tables should also be programmable. The main options to support multiple tables are to use different memories for each table or to have several tables share the same memories. In the first approach, each table would have to match the size and width of the memories to achieve an efficient memory usage. This is a severe limitation when flexible table size and entry width need to be supported. In the second approach, all the tables can dynamically share the memories, providing better flexibility. The problem is that the width of the memories needs to be dimensioned to support the largest entry size. This leads to significant memory waste for smaller entries. Hash based techniques like cuckoo hashing can be used to efficiently implement exact matching using standard SRAM memories, and are widely used in modern switches. However, current implementations only support entries of one size. This article presents the Single Double cuckoo hash, which can support elements of two sizes. Its main benefit is to improve memory utilization when multiple tables with entries of different sizes share the same memories. This is achieved at the cost of a small increase in circuit complexity.

Review of Roundabout Design Standards and the Development of a Roundabout Design Guideline for Sri Lanka

In Sri Lanka, the geometry of roundabouts has a considerable influence on their operation. The increase in road traffic and the large number of long vehicles that ply on the roads have contributed to the malfunctioning of some of these roundabouts. The objectives of this study were to review the roundabout design guidelines, identify issues in the existing roundabouts and prepare a roundabout design guideline appropriate for Sri Lanka. Twenty four roundabouts located in some of the major cities were selected for the study. The design parameters of the geometries of the selected roundabouts were compared with those recommended in five major design guidelines. Data on the main geometric parameters of each roundabout were collected through field measurements and calibrated satellite images. The dimensions and the design parameters of these roundabouts were compared with those stated in a few international roundabout guidelines. A swept path analysis was carried out on selected roundabout layouts for single unit trucks to determine the adequacy of their entry widths, circulation widths, exit widths and operational speeds. The entry radiiwere higher than those recommended in the international standards. The design parameters of the existing roundabouts that required improvements were identified and suitable values for the selected design parameters have been proposed. Most of the roundabouts meet the minimum requirements specified in the international guidelines for the centre island diameter (100%), circulation width (92%), and exit radius (92%).

Roundabout Accident Prediction Model: Random-Parameter Negative Binomial Approach

Roundabouts have been used widely on all road classes in the United Kingdom because they are considered safer than other types of intersections in general. The objective of this study was to examine geometric and traffic characteristics and their influences on the number of accidents. Data from each of 70 roundabouts (with 284 approaches) included all recorded vehicle accidents as well as geometric and traffic characteristics for the entire roundabout, within circulatory lanes, and at roundabout approaches. Resulting estimates were compared with those from random-parameter and fixed-parameter negative binomial count data models. The random-parameter results provided better goodness of fit than the fixed-parameter results, and more variables were found to be significant. Significant variables that influenced the number of accidents were total approach traffic, truck percentage, entry width, inscribed circle diameter, number of lanes, and presence of traffic signals.

Ultrasound biomicroscopic study of the effects of topical latanoprost on the anterior segment and ciliary body thickness in dogs.

The goal of this study was to evaluate the effects of topical latanoprost on the anterior segment and ciliary body using ultrasound biomicroscopy (UBM) in dogs. This study included six eyes of six clinically normal beagles. UBM scans were performed on six sedated dogs before and 2 h after topical latanoprost instillation. From the next day on, latanoprost was topically applied twice daily for 7 days. After 1 week of instillation, the UBM scans were repeated. The ciliary body thickness (CBT) and the anterior segment parameters, including the iridocorneal angle (ICA), the width of the ciliary cleft (CC) entry, the length of the CC, and the width of the mid-CC, were measured. The topical latanoprost decreased the ICA and CC entry width and increased the mid-CC width without any significant alterations in the CC length. There were time-dependent alterations in the CBT: a reduction in the CBT after 2 h of instillation and rebound thickening after 1 week of instillation. The topical latanoprost widened the ciliary cleft despite the narrowing of the ICA and CC entry. Time-dependent alterations in the CBT were demonstrated by the UBM and might be a reflection of the mechanism of the uveoscleral outflow enhancement induced by the topical latanoprost.

Entry zone of iliac screw fixation to maintain proper entry width and screw length.

To evaluate the entry zone of iliac screw fixation to maintain proper entry width and screw length. Computed tomography images of pelvic bones from 90 human cadavers were reconstructed into 3-dimensional models. In each model, a sectional image crossing the posterior superior iliac spine (PSIS) and anterior inferior iliac spine (AIIS) and consecutive sectional images up to 20 mm superiorly and inferiorly from the PSIS with 1-mm intervals aiming the AIIS were obtained. One virtual iliac screw with 10-mm diameter was introduced onto the PSIS at the middle and at the lateral and medial 1/4 points on the prominence of the posterior iliac spine. The entry width of the bony prominence and the corresponding maximal screw length available were evaluated for each entry point. The entry width was smallest on the inferior 20 mm (4.7 ± 3.0 mm) and gradually increased up to the superior 10 mm (19.1 ± 3.9 mm) sectional images. The maximal screw length was smallest on the superior 20 mm (76.7 ± 39.7 mm) and gradually increased down to the inferior 10 mm (112.3 ± 15.1 mm) sectional images. The maximal screw lengths were significantly greatest at the most medial point and smallest at the most lateral point on the superior 20- and 10-mm sectional images and at the PSIS. The iliac screw fixation entry zone to maintain proper screw length and entry width is outlined from 20 mm superiorly to 10 mm inferiorly from the PSIS and is located more medially from the prominence of the posterior iliac spine.

Effects of task precision demands on behavioral and physiological changes during a repetitive asymmetric lifting activity.

This study investigated the effects of task precision demands on behavioral and physiological changes during repetitive asymmetric lifting. Repetitive lifting encountered in manual material handling leads to muscle fatigue and is a documented risk factor for low back disorder. A total of 17 healthy volunteers performed repetitive asymmetric lifting for 60 min (10 lifts/min). Task precision demands were imposed by varying the entry width onto the destination conveyor. Physiological changes were assessed using near-infrared spectroscopy obtained from the erector spinae muscles. Three-dimensional spine kinematics and moment responses were quantified to understand behavioral changes during the lifting activity. Task precision demands showed no effect on erector spinae muscle oxygenation levels. Behavioral changes associated with repetitive lifting included increases in the overall lift duration, peak forward bending motion, and three-dimensional movement velocities of the spine, along with a decrease in the lateral bending moment. Relative to low precision demands, high precision demands resulted in 20% longer placement periods, which, in turn, resulted in a 12% increase in the time-integrated twisting postures and a 10% increase in the time-integrated lateral bending moments during load placement. The elevated risk of low back injury when lifting under greater precision demands is likely due to the sustained spine twisting and the sustained lateral bending moment on the spine in the final phase of these lifts. Understanding behavioral changes to repetitive asymmetric lifting, especially for tasks requiring greater precision can be used to support injury prevention efforts.

Modeling Through Traffic Speed at Roundabouts Along Urban and Suburban Street Arterials

A total of 30 roundabouts with different dimensions and characteristics were selected from three cities in Jordan. The collected data included the approaching road free flow speed (FFS), area type, entry width, circulating roadway width, exit width, roundabout internal and external circle diameters, circulating roadway super elevation, entry deviation angle, and drive curve. The regression analysis showed that the entry width, internal circulating diameter, entry deviation angle, approaching FFS, and drive curve were significant in determining the average and 85th percentile roundabout circulating speed. The developed model was compared with other international models developed in the United States and Italy.

Modeling and calibrating capacity of large roundabouts

Roundabout models, available in the literature widely, vary between one method and another. Majority of the models are solely based on circulating flow to estimate capacity. The relationship between maximum entry flow of large dual and triple lane roundabouts and their geometric and traffic characteristics is investigated here for saturated flow condition using multivariate analysis. The developed model, based on the data gathered from 13 roundabouts in Bahrain, matched the field data reasonably well. The significant predictors, out of 60 tested ones, included circulating and exiting flows, number of entry and circulating lanes, circulating and entry widths, inscribed diameter and flare length. Capacities predicted through various international models varied considerably with both the developed model and the field data. The international models were then calibrated against the model, and consequently the field data, so as to have significant match with the two. The procedure followed in developing the model and calibrating the international models consisted of eight stages. It involved identification of significant correlation of individual predictor with capacity, multivariate regression analysis, model smoothing, multi-collinearity test, redevelopment of the model after adjusting the variables causing collinearity, comparison analysis with seven known international models and calibration of the international model. While UK, aaSIDRA and French models required around 50% reduction to match the developed model and actual data; US FHWA and Swiss models required 25% reduction and US HCM and German models required just 8% adjustments. Such clear variations call for further research. The findings assist the urban planners as when to shift from one type of intersection control into another involving roundabout, and vice versa. Keywords Adjustment factor, calibration, circulating flow, exiting flow, maximum entry flow, roundabout capacity Language: en

Comparison between Simulated and Experimental Crossing Speed Profiles on Roundabout with Different Geometric Features

Many researchers have shown in recent studies how roundabouts speed distribution, together with other features (entering flow, circulating flow, entry curvature, entry path radius, entry width, approach width, ratio of inscribed circle diameter/central island diameter, angle to next leg, etc.), can be used as a measure of safety level for these intersections. The wide use of different micro-simulation models for a preventive analysis of roundabouts performance (capacity, delays, levels of service, etc.) highlights the need for a deeper study of the most sensitive parameters for a better fitting between simulated and observed traffic conditions.This work is based on an experimental analysis of the crossing movement in two roundabouts characterized by different values of the inscribed circle diameter (D1≈½•D2) and located close together on the same road in the University Campus of Arcavacata, Italy. The main aim of the research is the suggestion of a methodological approach to the simulation process of the through movement by the use of VISSIM® micro-simulation software. Resultsconcern the following issues: (i) coherence validation of experimental data regarding speed distributions along the crossing movement as a function of roundabout radius; (ii) methodological and procedural issues related to the implementation of simulation parameters in VISSIM, particularly referring to speed distributions along the crossing movement, in order to better understand the effects of the change of roundabouts geometric features on simulation results.

Safety analysis of roundabout designs based on geometric and speed characteristics

The study investigates data concerning crashes at roundabouts in order to identify the major factors influencing such events in South Korea. In this investigation, three stages of research tasks were carried out. First, crashes which occurred at South Korean roundabouts were categorized and subsequently compared with international cases. Second, field surveys were conducted in order to investigate how vehicle speeds influence the occurrence of accidents. Third, a statistical analysis was performed in order to investigate the correlation between roundabout geometry and crash occurrences and to reveal major geometric elements of roundabout safety. It was revealed in the study that most vehicles slow down substantially around roundabouts and recover their speed after the roundabouts. Based on the statistical analysis, it was found that negative binomial distribution would give a better performance. In addition, in contrast to cases in the US, the final selection of the independent variables includes as follows: the number of approaches, the number of entering lanes, the entry width, the flare width, the number of circulating lanes and the circulating lane width. Finally, the study provided a model with which to capture the relationship between geometric design elements and the occurrence of crashes at roundabouts. It is anticipated that this model will be applied by engineers to better predict crash occurrences at roundabouts.

Micro electrochemical sinking and milling method for generation of micro features

Micro features are generated on SS-304 stainless steel by electrochemical micromachining. This research aims at the development of best method of micro profile generation for micro components based on electrochemical micromachining in terms of reduced taper angle, overcut, edge deviation and time of machining using cylindrical micro tool. Sinking and milling method is a new approach to microchannel generation, where a micro tool moves vertically to final depth or required depth of machined feature followed by milling along the path of the micro features. The experimental study of process parameters such as pulse frequency of applied voltage, electrolyte concentration, pulse width, micro tool feed rate, machining time and depth of sinking by micro tool is conducted for the investigation and comparative analysis of their effects on material dissolution during micro profile generation utilizing scanning layer-by-layer method as well as sinking and milling method. Machining zone has been simulated in two positions of micro tool, and it has been established that taper less through microchannels can be generated by the scanning method and the sinking and milling method. Complex taper less micro features such as channel net, “U” shape and “S” shape were machined. Micro profile of narrow entry width of 32 µm was machined on 50-µm-thick SS-304 sheet. Very narrow micro profile of 23 µm was also machined on 35-µm-thick SS-304 sheet by the fabricated micro tool of ϕ = 8 µm utilizing the new approach of sinking and milling in electrochemical micromachining.

Experimental study on supporting technology of gob-side entry with different roof conditions

Aiming to effectively solve the problem of deep mining with safety and high efficiency, according to geological conditions, production and stress analysis in roadway surrounding rock, experimental studies on roadway supporting of workface 103 under three types of roof conditions with different supporting technologies and parameters were carried out based on the theory of supporting technology of gob-side entry. The results show the supporting of gob-side entry retaining is successful, and the deep surrounding rock is effectively controlled by field monitoring and drilling-hole photos. After stress in surrounding rock of roadways restores stable, the final roadway deformation of surrounding rock of haulage roadway and air-roadway are both about 300 mm; width of gob-side entry is 3.8–4.0 m and average height is 2.0–2.2 m; roadway section is above 8.0 m2, which solves the problems of gob-side entry retaining support strength and safe mining; necessary conditions of mining safety in workface 103 are met.

Performance studies on an oscillating water column employing a Savonius rotor

A new oscillating water column (OWC) design is proposed in this study to incorporate a simpler Savonius type turbine. Conventional OWC devices employ a bi-directional turbine such as a Wells or an Impulse turbine to extract energy from the air. The disadvantages of the Wells turbine include its inability to self start and stalling. The Savonius turbine is much cheaper and is an effective option at low Reynolds numbers. In the current rectangular OWC device, unlike the circular OWC, the width of entry of the capture chamber can be increased without being influenced by the diameter at the turbine section. To improve its primary capture efficiency, the front and rear walls of the OWC are inclined to minimize reflection. The Savonius rotor characteristics are studied with respect to the change in frequency of the incoming waves. The rotor rpm is sensitive to wave period and primary conversion efficiency while changes in depth only affect the rotor rpm at lower frequencies. The Savonius rotor shows promising results and can be incorporated into large scale OWC devices to reduce costs of the turbine component of the system.

Compacting register file via 2-level renaming and bit-partitioning

A large multi-ported rename register file (RRF) is indispensable for simultaneous multithreaded (SMT) processors to hold more intermediate results of in-flight instructions from multiple threads running simultaneously. However, enlarging the RRF incurs longer access delays and more power consumption, both of which are critical to the overall performance and are becoming a bottleneck due to the ever-increasing pipeline depth and issue width in future SMT processors. We propose a novel register renaming scheme called Multi-usable Rename Register with 2-Level renaming and allocating ( 2L-MuRR), which focuses on more efficient utilization of a fewer number of rename registers. Based on the fact that the effective bit-width of most operands is narrower than the full-bit width of a register entry, 2L-MuRR partitions each rename register into several fields of different widths. Either a single field or a field combination can hold an operand, thus making each rename register multi-usable. In addition, 2L-MuRR postpones the register allocation to the write-back stage, which is similar to the formerly proposed virtual–physical-register (VPR) scheme, further reducing the meaningless RRF occupancy. The simulations show that 2L-MuRR improves the efficiency of the RRF significantly, achieving higher performance with much fewer rename registers. For example, when the RRF size is 60, 2L-MuRR outperforms Trad (traditional register renaming approach) and VPR in terms of IPC by 38% and 11%, respectively, while decreases the RRF occupancy by 37% and 15%, respectively.

Convective heat transfer in porous channels with 90-deg turned flow

This study experimentally investigated the convective heat transfer and pressure drop in porous channels with 90-deg turned flow. Aluminum foams with a porosity of 0.93 were used. The size of the aluminum foams was fixed. Variable parameters were the ratio of the entry width to the porous sink height ( W j / H), the pore density of the aluminum foam (PPI, pore per inch) and the Reynolds number ( Re). Experimental results reveal that the wall temperature was maximal at the corner under perpendicular flow entry. It fell along the channel axis until x/ H was about 1.0, finally approaching a constant value. Parametric studies indicate that increasing Re increased the average Nusselt number ( Nu ¯ ) and the effects of W j / H and PPI on Nu ¯ were negligible. The friction factor ( C f) generally declined as Re increased, PPI decreased or W j / H increased. Besides, increasing W j / H or reducing PPI slightly increased Nu ¯ at a given pumping power. Additionally, the heat transfer and pressure drop in porous channels with straight flow were also measured for comparison.

Optimizing geometric design of single-lane roundabouts: consistency analysis

One of the main objectives to promote traffic safety at roundabouts is design consistency. Design consistency ensures that the speed differences along a vehicle path or between conflicting paths are smaller than a specified criterion. Traditionally, roundabout design involves an iterative process. Initially, the vehicle path radii are determined from drawing each path by freehand on the proposed roundabout geometry, and then the speeds along path elements are calculated. The process is repeated until design consistency is satisfied. This paper presents an optimization model that directly provides the design parameters that maximize design consistency. The radii of different vehicle paths (through, right, and left) are mathematically modeled for given design parameters. The optimum design parameters include vehicle path radii, approach entry widths, inscribed circle diameter, circulating width, and central island diameter. The optimization model is applicable to single-lane roundabouts with four legs intersecting at right angles. The proposed model not only makes the design process more efficient, but also guarantees the optimum design consistency.Key words: geometric design, roundabouts, horizontal curve radius, consistency, safety, optimization.

ENTRY AND CIRCULATING FLOW RELATIONSHIP AT A ROUNDABOUT

This study examined the two formulas stated in the Arahan Teknik (J) 11/87 of the Malaysian Public Work Department to estimate the capacity of small and conventional roundabouts. Field survey, which cover the roundabout inventories, and vehicle classification were carried out. Vehicle classification survey indicates lower entry flows at the single lane entries compared to the multilane entries for both morning and evening peak hours. Statistical analysis was used to identify the correlation between the circulating flows, entry flows and the entry width. Results showed that the capacity obtained from the weaving concept was generally higher than the regression equations for the single and multi entries. The difference between these results may be due to the regression equations that consider the interaction between the entry and circulating flow and the geometric parameters, while the Arahan Teknik (J) 11/87 only address the geometric parameter. The entry flows for both single and multilane entries were highly dependent on the circulating flows.

Development of a Delay Model for Roundabouts in Jordan

The purpose of this research was to develop a model for estimating roundabout delay as a function of the influencing traffic and geometric factors. Fourteen roundabouts were selected from different cities in Jordan. Circulating volume, entry volume, and entry delay were measured during peak and off-peak periods using video cameras. Data on geometric design elements including circulating width, entry width, and roundabout diameter were measured through field survey. An empirical approach was used to develop a delay model as a function of the influencing factors based on a time interval of 15 min. The analysis indicated that geometric variables have significant effects on the roundabout entry delay. The entry width has the greatest influence, whereas the circulating width has the least influence. A comparison between delay models produced using different time intervals showed that, as time interval increases, R2 increases. The SIDRA delay model was validated using the field delay data, and it was found that...

Effects of drying on Amazonian ferralsols and podzols. Determination of water desorption curves from mercury porosimetry

We established pedotransfer functions to define the water desorption curve from MIP, organic carbon content, and bulk density (table I and II). These functions can be used for soils with the following characteristics, thus for most tropical soils: - negligible fine clay (< 0.2 [nu]m) content, in order to enable the extrapolation of nanopore volume from MIP, without needing nitrogen desorption [Bruand and Prost, 1987]; - soils mainly composed of kaolinite and quartz. The organic carbon content has little influence on the humic podzol studied here, so the equations established here are pertinent for other podzols. These pedotransfer functions give information on the structure of these soils : - residual and micro- porosities modify between MIP and water desorption, according to the organic carbon content and the texture of clay (given by the average textural pore size), with the same law for all soils; - mesoporosity changes according to two different types of structure : (1) clay microaggregates for clayey soils, (2) sandy fabric for podzol, loose at depth due to eluviation of parent clay, consolidated near the surface by pedoturbation; - total porosity follows, with an attenuation, the changes in the MO-linked porosity and in the porosity linked to soil structuring particles, that is the residual porosity for clayey soils, and the mesoporosity for podzols; - macroporosity, in reality as in the equations, compensates for the difference. This method could be tested on soils with other granulometry, mineralogy, or higher OM content. This work was supported by IRD and the PEGI and PROSE programs, we thank Max Sarrazin for his technical collaboration and the reviewers for their critical reading.

Prediction of room closure and stability of panel 1 in the Waste Isolation Pilot Plant

The Waste Isolation Pilot Plant (WIPP) is intended to be an underground repository for the permanent disposal of transuranic radioactive waste generated by defense activities. Both surface and underground facilities, including one waste panel, were excavated during the period from 1982 to 1988. The decision to use the repository for disposal has not vet been made. The objective of this paper was to predict room closures and ground conditions for Panel 1 based on an analysis of extensive deformation data collected by Westinghouse Engineering from 119 instrumented locations throughout the WIPP facility. This study was important for both maintaining the safety of personnel and assuring the continuity of waste emplacement operations, given that the anticipated service life of the Panel 1 has nearly tripled from the original design life of 5 years. The technical approach consisted of (1) characterization of 11 mining, bolting, and geologic variables at individual instrumented locations (119 clusters), (2) development of a mathematical model (multilinear regression analysis using stepwise inclusion of independent variables), (3) examination of the results, and (4) prediction of entry closures and ground conditions for the anticipated life of the facility given the specific geologic, mining, and support conditions at selected waste panels and access entries. Based on an examination of standardized regression coefficients, several significant variables were identified that influence entry closure and long-term stability. These were excavation ratio, entry width, roof beam thickness, entry height, and age. Interestingly, bolting variables did not help explain variability in the data and thus were not included in the mathematical model. Considering the present roof conditions, anticipated future deformation, and mining experience with variety of proven roof support systems, it was concluded that only portions of Panel 1 may be used for waste emplacement with a reasonable degree of confidence.