Compaction Ratio Research Articles

Compact silicon-based polarization-independent directional coupler using subwavelength gratings.

A compact and high extinction ratio polarization-independent directional coupler (PIDC) using silicon-based subwavelength gratings (SWGs) is proposed and analyzed in detail, where the SWG structures are located between the two input/output strip waveguides together with input/output SWG-based transitions. The introduced SWG-based structures can effectively enhance the coupling strength for the TE mode, while that for the TM mode is hardly affected. According to the coupled-mode theory, by carefully choosing the structural parameters, the coupling length for both polarizations can be identical; thus a PIDC is realized. Results show that a PIDC with a coupling length of 9.2μm is achieved, and the extinction ratio, insertion loss, and reflection loss are 33.25/31.41dB, 0.224/0.121dB, and -23.11/-26.31 dB, respectively, for the TE/TM mode. In addition, fabrication tolerances to the key structural parameters are analyzed in detail, and field evolution through the present device is also presented.

The effects of compaction methods and mix parameters on the properties of roller compacted concrete mixtures

Despite the wide use of RCC, there is no specific compaction methodology developed to simulate the site conditions in the laboratory. Yet, there are few compaction methods that are generally used to produce RCC specimens in the laboratory environment. The most common methods are the vibrating table and the vibrating hammer found in ASTM, and the modified proctor and Superpave gyratory compactor (SGC), which are suggested to be standardized. However, it is not well known how these different compaction techniques can reflect the properties of RCC in situ. In this study, RCC mixtures which consist of two different cement dosages and two types of aggregate gradations were compacted by the four laboratory compaction methods mentioned above, to investigate the effect of laboratory compaction methodology on the physical properties and mechanical performance of RCC. The first three methods are the ones commonly used in the literature, while the fourth method (SGC) is thought to best represent the field compaction conditions with the kneading action. Moreover, regressions models were derived for each of the compressive and splitting tensile strengths based on the mix parameters. The statistical analysis showed that the compressive and splitting tensile strengths were highly affected by the compaction ratio, then by the cement content. The water content seemed to be dependent on the compaction ratio and had a small effect on the strengths. The ideal laboratory compaction methods in terms of strengths and compaction ratio within the acceptable Vebe consistency time were determined as the SGC first and the vibrating hammer second.

A compact and lightweight liquid-cooled thermal management solution for cylindrical lithium-ion power battery pack

Battery thermal management (BTM) is indispensable to the battery pack of electric vehicles (EVs) for safety. Among different types of BTM technologies, liquid cooling shows its superiority with high heat transfer coefficient and low power consumption. However, the previous works paid little attention to the compactness and weight ratio of liquid-cooled BTM system, which is vital to the specific energy of battery pack. In this study, a compact and lightweight liquid-cooled BTM system is presented to control the maximum temperature (Tmax) and the temperature difference (ΔT) of lithium-ion power battery pack. In this liquid-cooled solution, one thermal conductive structure (TCS) with three curved contact surfaces is developed to cool cylindrical battery. The influences of mass flow rate (mf), inner diameter (d), contact surface height (h) and contact surface angle (α) of the TCS are investigated through numerical study. It is found that for the 5C discharge rate process of battery, Tmax can be maintained within 313 K when mf is larger than 1 × 10−4 kg/s. A weight sensitive factor is defined to evaluate the influences of d, h and α on ΔT and the weight of TCS. It is found that d is the most important parameter that influences the weight. h is the secondary parameter, and α is the parameter with the minimal impact on the weight. Then the values of d, h, and α are designed to reduce the weight of TCS while maintaining its cooling performance. The designed TCS can control Tmax under 313 K with ΔT as 4.137 K. Compared to the original TCS, ΔP, ΔT and the weight are respectively reduced by 80%, 14% and 46% for the designed TCS. Furthermore, the performance of liquid-cooled system with parallel TCSs is discussed. The flow distribution among parallel TCSs is improved through designing the positions of the inlet and the outlet, which enables that Tmax and ΔT of battery pack is similar to the ones of a single battery. The present study facilitates the guideline for compact and lightweight design of liquid-cooled battery thermal management system.

THE COMPACTNESS INDICATORS OF SOLIDS APPLIED TO ANALYSIS OF GEOMETRIC EFFICIENCY OF BUILDINGS

The authors redefine and generalize the so-called relative ratio of compactness of solid with respect to sphere and cube introduced by Mahdavi and Gurtekin. The authors propose such new indicators as a relative ratio of solid compactness in the shape of a prism-shaped solid related to a cuboid with a square base and a given height (e.g. the height of the analyzed storey), a solid compactness indicator defined for the basis of the prism relative to the square. They introduce also other indicators: a relative defect of the perimeter and area. The test of indicators formulated and described in the paper was carried out in two groups of buildings: existing (spotted locally) and those whose designs can be found in the selected catalog available on the website. In addition to the compactness ratios calculated for existing and designed buildings, an analysis of the size of the indicators for the adopted building research models was made. Proposed indicators allow for a description of the compactness of the building model with an indication of the deviation from the real ideal solid. The introduced geometric determinants of solids may be useful in the initial phase of searching for satisfactory design solutions.

Evolution of rivulets during spreading of an impinging water jet on a rotating, precoated substrate

The spreading of a liquid film across a rotating surface is inherently unstable due to the centrifugal force, which causes the formation of rivulets along the spreading front. This instability produces a rich diversity of spreading patterns and is important to control for the optimization of spin-coating and spin-rinsing of silicon wafers during the fabrication of microelectronics. The present work is an experimental investigation of the evolution of rivulets arising from this instability during the spreading of an impinging water jet across a rotating substrate that is precoated with a thin, aqueous film. To characterize these rivulets, we developed a high-speed imaging apparatus and image-processing software that traces the spreading front over time. We show how the morphology of the spreading front is qualitatively affected by varying the Reynolds number of the impinging jet, the ratio of centrifugal to Coriolis forces, and the type of liquid used to precoat the substrate. For quantitative analysis of rivulets, we measured the “compactness ratio” of the spreading front, which quantifies deviation from a circular spreading front. We used the compactness ratio to demonstrate that rivulets are suppressed most strongly at low rotation rates, at high flow rates, and on substrates precoated with water, although with notable exceptions.

Soil Stabilization using Brick Kiln Dust and waste Coir Fibre

Stabilization of clay soil has been carried out for improving its engineering properties of soil. To stabilize the clayey soil use Brick Kiln Dust of and waste Coir Fibre, an experiment is conducted to evaluate the properties of soil mixing with 10%, 20% &30% percentage of Brick Kiln Dust and Coir Fibre contents of 0.5%, 0.75% and 1.0% by weight of soil sample and then the tests are performed. Tests conducted for clayey soil mixed with Brick Kiln Dust and Coir Fibre are Liquid Limit, Plastic Limit, Compaction (OMC & MDD), and California Bearing Ratio (CBR). Flexible pavements sections were degined for non-stabilized and stabilized subgrades to be standard axles traffic intensities. The preamble of brick kiln dust and coir fiber is analyzed to improve the features of expansion subgrade materials and other sub-base materials. Also design the thickness of pavement when it is stabilized with optimized brick kiln dust and coir fiber. The results reveal that CBR value increased with increase of Brick Kiln Dust and Coir fibre. The soil stabilization treatment significantly improved the engineering properties of the soil, and reduced the pavement thickness and also cost of the project.

Modeling Relations between Compacted and Uncompacted Crown Ratio for the Northern United States

Abstract Tree crown ratio is useful in various applications such as prediction of tree mortality probabilities, growth potential, and fire behavior. Crown ratio is commonly assessed in two ways: (1) compacted crown ratio (CCR—lower branches visually moved upwards to fill missing foliage gaps) and (2) uncompacted crown ratio (UNCR—no missing foliage adjustment). The national forest inventory of the United States measures CCR on all trees, whereas only a subset of trees also are assessed for UNCR. Models for 27 species groups are presented to predict UNCR for the northern United States. The model formulation is consistent with those developed for other US regions while also accounting for the presence of repeated measurements and heterogeneous variance in a mixed-model framework. Ignoring random-effects parameters, the fit index values ranged from 0.43 to 0.78, and root mean squared error spanned 0.08–0.15; considerable improvements in both goodness-of-fit statistics were realized via inclusion of the random effects. Comparison of UNCR predictions with models developed for the southern United States exhibited close agreement, whereas comparisons with models used in Forest Vegetation Simulator variants indicated poor association. The models provide additional analytical flexibility for using the breadth of northern region data in applications where UNCR is the appropriate crown characteristic.

A model for low mass compact objects

A model for low mass compact objects with compactness ratio $u\leq 0.06092997016$ is presented here. Density, pressure and sound speed are regular and monotonic decreasing functions. The change between the central density $\rho_c$ and the density on the surface $\rho_b$ is lower than $3.94\%$ and the maximum change occurs for the biggest compactness, i.e. $\rho_c=1.039350237\rho_b$. This allows us to apply this model for the case of compact stars in which the density variation is very small. In particular, we can use this model for PSR B0943 + 10, a quark star candidate, with radius $R=2.6{\rm Km}$ and mass $M=0.2 M_\odot$. According to our model it comes out that the density on the surface is $\rho_b=5.388074 \times 10^{17} Kg/m^3$ and its central density $\rho_c=1.007150 \rho_b$ is slightly bigger than the surface density and larger than the nuclear density.

Backfill mining alternatives and strategies for mitigating shallow coal mining hazards in the western mining area of China

This study addresses the major geo-environmental hazards caused by shallow coal mining in China's western eco-environment frangible area. These hazards are related to the high overburden pressure, surface subsidence, soil and water losses, and land desertification, with consequent vegetation and wildlife losses. To mitigate these hazards, three alternative backfill mining methods are proposed, for three typical shallow coal mining conditions, using aeolian sand-based backfilling materials, which are readily available in this area. The main influencing factor is the backfill material compaction ratio. Its effect on aquiclude deformation and water-conducting fracture evolution are assessed by numerical and physical simulation methods. The potential application of the proposed backfill coal mining alternatives is evaluated and discussed in detail. The results obtained are considered to be valuable for developing a strategy for the coordinated exploitation of coal resources and environmental protection in China's western frangible eco-environment area.

Two-dimensional microbend sensor based on the 2-core fiber with hump-shaped taper fiber structure

Abstract A novel two-dimensional bending vector sensor formed by cascading two hump-shaped tapers (HSTs) in a segment of 2-core fiber (2CF) is proposed and fabricated, in which the HSTs serve as the mode splitting and coupling. Several modes are excited at the first HSTs, where a part of the light energy is propagated within the center core of the 2CF, and the other part is coupled to the external core. Due to the effective refractive index difference between these core modes, they are recoupled into the lead-out single-mode fiber (SMF) at the second HSTs and interfere with each other. The bulge of the HSTs and two cores of the 2CF are distributed in a triangle. Owing to the asymmetric structure, the sensor can distinguish multiple bending directions. In addition, the linear spectral responses for bending and temperature are observed experimentally. The proposed sensor has many advantages, including compact, inexpensive, and high directional resolution ratio. Experiment results show that the sensor can distinguish bending directions and experience a maximum sensitivity of −6.182 nm/m−1 with a bending range of 0–0.98 m−1 without dead zone.

Parametric optimization of an architectural object’s form as a method to improve its energy efficiency

Parametric optimization of an architectural object’s form is one of the design tasks, which architects and project designers face at the stage of structural concept development and design. Improving the performance qualities of a design solution, while providing its energy efficiency, is the purpose of system research in the sphere of architecture and urban planning. The article gives the comparison of calculated compactness ratios of the external envelope for one-, two- and three-, four-, five-, six-, seven-storey 6-apartment compact-form residential houses, comparable in the floor surface area criterion. The application of BEM software packages on the basis of BIM-modeling of buildings is reasonable to substantiate with the optimal functional (consumer) properties of an architectural object. Systematic methodology allows considering the architectural and design problems in the interdisciplinary way. Computer modeling of architectural objects should solve the optimization tasks on the basis of version design and contain an optimization module, which would allow taking the optimal decision at the specified design constraints (conditions) and normative parameters. Computer modeling of architectural objects with the use of structural optimization methods for the version design is a promising area, which requires the formalization of project procedures and developing automated design system tools for designing buildings of various purposes.

A cell-by-cell Monte Carlo simulation for assessing radiation-induced DNA double strand breaks

This paper presents a cell-by-cell Monte Carlo simulation study that combines charged particle track structure data with an interphase cell nucleus model to quantify DNA double strand breaks (DSBs), spatial distribution of DSBs in a cell nucleus, and resulting potentially lethal or mutagenic events (PLMEs) between DSBs in close proximity. Cell nucleus is simulated according to the chromosome territory-interchromatin compartment (CT-IC) model in that chromatin content is unevenly distributed in chromatin domains (CDs) and IC with a chromatin compaction ratio of 22:1. A particle track structure coordinate (PTSC) library was first generated for each particle type, energy, and dose based on a large number of particle track data obtained by running the Monte Carlo track structure code Geant4-DNA. To assess the DNA DSBs of a cell for a specific particle type, energy, and dose, the corresponding PTSC was selected and “map overlaid” onto 960 unique cell nucleus data sets containing chromatin fiber (CF) locations. Clustering algorithm DBSCAN was next used to identify the clustered energy deposition events occurring inside the CF. These events were then converted to DNA DSBs using a probabilistic approach. The locations of the DSBs thus obtained were, in turn, used to calculate PLMEs within the cell nucleus that can result from DSB proximity and complexity. The results obtained from this simulation study are correctly correlated to the experimental data of DSB yield and the RBE-LET relationships for various types of charged particles and of various energies. The results show agreement with other published radiobiological models.

Quantification of human bone microarchitecture damage in press-fit femoral knee implantation using HR-pQCT and digital volume correlation

Primary press-fit fixation of femoral knee prostheses is obtained thanks to the inside dimensions of the implant being undersized with respect to the bone cuts created intra-operatively, dictated by a press-fit specified by the implant design. However, during prostheses press-fit implantation, high compressive and shear stresses at the implant-bone interface are generated, which causes permanent bone damage. The extent of this damage is unknown, but it may influence the implant stability and be a contributing factor to aseptic loosening, a main cause of revisions for knee arthroplasty. The aim of this ex-vivo study was to quantify, using high-resolution peripheral quantitative computed tomography (HR-pQCT) imaging and Digital Volume Correlation (DVC), permanent bone deformation due to press-fit femoral knee implantation of a commonly used implant. Six human cadaveric distal femora were resected and imaged with HR-pQCT (60.7 μm/voxel, isotropic). Femurs were fitted with cementless femoral knee implants (Sigma PFC) and rescanned after implant removal. For each femur, permanent deformation was examined in the anterior, posterior-medial and posterior-lateral condyles for volumes of interest (VOIs) of 10 mm depth. The bone volume fraction (BV/TV) for the VOIs in pre- and post-implantation images was calculated, at increasing depth from the bone surface. DVC was applied on the VOIs pre- and post-implantation, to assess trabecular bone displacements and plastically accumulated strains. The “BV/TVpost/BV/TVpre ratio vs. depth” showed, consistently among the six femurs, three consecutive points of interest at increasing bone depth, indicating: bone removal (ratio<100%), compaction (ratio>100%) and no changes (ratio = 100%). Accordingly, the trabecular bone displacement computed by DVC suggested bone compaction up to 2.6 ± 0.8 mm in depth, with peak third principal strains of −162,100 ± 55,000 με (mean absolute error: 1,000–2,000 με, SD: 200–500 με), well above the yield strain of bone (7,000–10,000 με). Combining 3D-imaging, at spatial resolutions obtainable with clinical HR-pQCT, and DVC, determines the extent of plastic deformation and accumulated compressive strains occurring within the bone due to femoral press-fit implantation. The methods and data presented can be used to compare different implants, implant surface coatings and press-fit values. These can also be used to advance and validate computational models by providing information about the bone-implant interface obtained experimentally. Future studies using these methods can assist in determining the influence of bone damage on implant stability and the subsequent osseointegration.

Impact of repeated loading on mechanical response of a reinforced sand

Pavements constructed over loosely compacted subgrades may not possess adequate California bearing ratio (CBR) to meet the requirements of pavement design codes, which may lead to a thicker pavement design for addressing the required strength. Geosynthetics have been proven to be effective for mitigating the adverse mechanical behaviors of weak soils as integrated constituents of base and sub-base layers in road construction. This study investigated the behaviors of unreinforced and reinforced sand with nonwoven geotextile using repeated CBR loading test (followed by unloading and reloading). The depth and number of geotextile reinforcement layers, as well as the compaction ratio of the soil above and below the reinforcement layer(s) and the compaction ratio of the sand bed, were set as variables in this context. Geotextile layers were placed at upper thickness ratios of 0.3, 0.6 and 0.9 and the lower thickness ratio of 0.3. The compaction ratios of the upper layer and the sand bed varied between 85% and 97% to simulate a dense layer on a medium dense sand bed for all unreinforced and reinforced testing scenarios. Repeated CBR loading tests were conducted to the target loads of 100 kgf, 150 kgf, 200 kgf and 400 kgf, respectively (1 kgf = 9.8 N). The results indicated that placing one layer of reinforcement with an upper thickness ratio of 0.3 and compacting the soil above the reinforcement to compaction ratio of 97% significantly reduced the penetration of the CBR piston for all target repeated load levels. However, using two layers of reinforcement sandwiched between two dense soil layers with a compaction ratio of 97% with upper and lower thickness ratios of 0.3 resulted in the lowest penetration.

Rearranging Online Tubes for Streaming Video Synopsis: A Dynamic Graph Coloring Approach.

To efficiently browse long surveillance videos, the video synopsis technique is often used to rearrange tubes (i.e., tracks of moving objects) along the temporal axis to form a much shorter video. In this process, two key issues need to be addressed, i.e., the minimization of spatial tube collision and the maximization of temporal video condensation. In addition, when a surveillance video comes as a stream, an online algorithm with the capability of dynamically rearranging tubes is also required. Toward this end, this paper proposes a novel graph-based tube rearrangement approach for online video synopsis. The relationships among tubes are modeled with a dynamic graph, whose nodes (i.e., object masks of tubes) and edges (i.e., relationships) can be progressively inserted and updated. Based on this graph, we propose a dynamic graph coloring algorithm to efficiently rearrange all tubes by determining when they should appear. Extensive experimental results show that our approach can condense online surveillance video streams in real time with less tube collision and high compact ratio.

Evaluation of Cement-Stabilized Mine Tailings as Pavement Foundation Materials

Waste disposal is an important topic for cities today. We have shown for the first time how to make sewage sludge disposal safer, more environmentally friendly and still to obtain some benefit from it, namely energy, from its organic content. The main purpose of this paper is to present a laboratory tests results based on investigation carried out on the tailings of Boukhadra Mine in Algeria, in order to find out their suitability for use in road embankments, and pavement foundations. Three types of tailings, namely as marl, limestone and iron ore wastes, were initially tested to find the most suitable of them for application in pavement structures. Having presented more compliant properties, limestone waste, after being treated with cement, was tested with modified Proctor compaction, compressive strength (CS) and California Bearing Ratio (CBR) tests. At 2% intervals, the cement content of the mixtures is varied from 0 to 6%. Test results showed that an increase of cement content in the mixture would increase maximum dry density and decrease optimum moisture content of the compacted mixture. The increases in CBR and CS values qualifying the mixtures for use in Algerian pavement foundation were also noted, indicating that the limestone waste from Boukhadra Mine has the potential to be directed to an outlet for recycling.

What can be learned about the deposition and compaction of peat from the Miocene lignite seam exposed in the Chłapowo Cliff on the Polish coast of the Baltic Sea?

This study focuses on discussing the relationship between the accumulation of peat and its compaction in the overbank zone of the Miocene river system. The examined 2nd Lusatian lignite seam is characteristically interbedded with sandy deposits and these are less compressible than peat. Therefore, in favourable conditions such as those found at Chlapowo Cliff (on the Baltic Sea coast in northern Poland), it is possible to identify the effects of an even or uneven lowering of the mire surface, resulting from diversified compaction of the underlying phytogenic beds. The research problem was applied to two examples located close to each other within the lignite seam. The first case shows the accumulation of fresh peat layers of almost equal thickness, while the second one presents a reduction in the thickness of fresh peat beds over the fossilised channel-fill sandy body. Only the latter example allows us to calculate the peat-to-lignite compaction ratio. The results of the compaction ratio obtained, Cr ≈ 7.37, mean that the youngest, fresh peat layers were compacted at least 7 times, transforming them into lignite beds. However, such a high compaction value, estimated for the top layers of the Miocene mire, cannot be directly taken into account when reconstructing the total thickness of the peat seam prior to covering it with mineral overburden. The published peat-to-lignite compaction ratios, determined using other research methods, for the 2nd Lusatian lignite seam or its stratigraphic equivalents range from 1.7 to 6.0 in most cases, with averages of 2.2 to 4.0. The differences between the data in the literature and the results given in this paper are due to the fact that the process of peat/lignite compaction is ongoing and cumulative.

Impacts of Urban Expansion on Urban Heat Island - A Geospatial Approach

Growing urbanisation has led to increase in the built up area, reduction in open and green spaces with in the cities and the periphery. The urban saturation and the enlargement of the built space have determined environmental changes, increasing the already precarious condition of the natural systems in these spaces of high saturation. It results in to the formation of Urban Heat Island (UHI). Over the last few years, Ahmedabad has experienced rapid urbanization and associated Urban Heat Island (UHI) effects. This study aims at analysing spatially and temporally, the impact of urban form expansion on UHI in Ahmedabad using Landsat thermal images. The Mono Window Algorithm has been used to retrieve Land Surface Temperature (LST) from the thermal bands of LANDSAT-5, 8 TM satellite data. Various spatial analysis techniques were used to explore the relationships between area, compactness ratio, the gravity centers of urban land, and UHI. Under the similar urban land area condition, UHI and compactness ratio of urban land were in positive correlation. The moving direction of the UHI gravity center was basically in agreement with urban land sprawl. The encroachment of urban land on suburban land is the leading source of UHI effect. The results suggest that urban design based on urban form would be effective for regulating the thermal environment.

Fault Injection and Test Approach for Behavioural Verilog Designs using the Proposed RASP-FIT Tool

Soft-core processors and complex Field Pro-grammable Gate Array (FPGA) designs are described as an algorithmic manner, i.e. behavioural abstraction level in Hard-ware Description Languages (HDL). Lower abstraction levels add complexity and delays in the design cycle as well as in the fault injection approach. Therefore, fault simulation/emulation techniques are demanded to develop an approach for testing of design and to evaluate dependability analysis of FPGA designs at this abstraction level. Broadly, the fault injection techniques for FPGA-based designs at the HDL code level are categorised into emulation and simulation-based techniques. This work is an extension of our previous methodologies developed for FPGA designs written at data-flow and gate abstraction levels under the proposed RASP-FIT tool. These methodologies include fault injection by code parsing of the SUT, test approach for finding the test vectors using dynamic and static compaction techniques, fault coverage, and compaction ratio directly at the code level of the design. In this paper, we described the proposed approaches briefly, and the enhancement of a Verilog code modifier for the behavioural designs is presented in detail.

Effect of Drainage and Subgrade Compaction on Pavement Frosting Performance in Construction Zone

The roughness in the construction site surrounding condition and the pavement of the paths of the workzones makes a decrease in the efficiency in executive operation. Increasing the rolling resistance due to the roughness, is one of the reasons for reducing the speed of operation and delay in that. In this study first, the fields of roughness appearance are recognized including inflation due to frost of subgrade and executive operations areas, then frost depth are calculated which is affected by the density conditions and moisture amount of workzone area’s surface. The different percentages of moisture 2, 5, 7, 15 and 20 and compaction ratio 100, 90, 75, 65 percent were considered in this study for density of workzones' top surface. Frost depth calculations are carried out in the US - Army method and by Pavem-Calc software. The results show that an increase in the density of 40 % is caused by a 25 % increase in frozen strain. Furthermore, the increase of 15 % of pavement moisture causes a 20 % increase in the frost depth and the increase of surface roughness. Statistical analyses were carried out to investigate the effectiveness of the research variables and the classification of results in the classification method of CART algorithm.