Reference Length Research Articles

Dimensionless pressure drop number for non-newtonian fluids applied to Constructal Design of heat exchangers

This paper introduces a dimensionless group for pressure drop, named Bejan number (Be), to be used with non-Newtonian fluids. When defining Be for non-Newtonian fluids, it is necessary to choose a characteristic apparent viscosity to compose this dimensionless group. In non-Newtonian fluid dynamics, the viscosity at a characteristic shear rate is usually chosen as reference, with the latter given as the reference velocity divided by the reference length. When the flow rate is not known, a reference velocity may be taken as the square root of the pressure drop divided by the mass density. Thus, a characteristic apparent viscosity may be defined for any non-Newtonian model, even for one that does not present a characteristic viscosity defined explicitly in the viscosity function, such as the power-law model. The non-dimensionalization of motion equations for the crossflow of a power-law fluid between two aligned cylinders was performed using this philosophy. Some numerical tests were performed to corroborate the idea that the introduced form for Be is a good alternative to be used in experiments to predict and evaluate the heat transfer density in the context of Constructal Design of heat exchangers tube bundles.

Abstract 2582: KIRnome: KIR genotyping for whole genome/exome sequencing data

Abstract In this study, we tried to develop valid KIR calling algorithm from WES/WGS data. As a consequence, here we suggest KIRnome (KIR typing for whole genome and exome sequencing) which is a KIR typing method for applying sequencing data such as WES/WGS. A total of 71 sequencing data (18 WES and 53 WGS data, respectively) and matched experimentally validated KIR genotype data are used to train and validate. Before developing this method, two types of allele references (genomic and coding, here after called gSeq and cSeq) are constructed by allele sequence of IPD/KIR. KIRnome consists of two part, first part is calculating normalized depth (here after called depth) of 16 KIR genes and considering allele reference length and second is estimating KIR type based on depth. In general, we get higher normalized depth when using genomic references for WGS data and using coding references for WES data. This coincides with scheme KIRnome and the characteristics of WGS and WES data. Given 71 samples of 3 data sets, we evaluated KIR genotyping performance of KIRnome per each KIR gene. For all 16 KIR genes, KIRnome shows >=98.5% accuracy. When KIRnome performance was tested only in 13 WES samples, the accuracy slightly drops to 94%. We assume this is attributable to relatively small number of the samples. In conclusion, we developed a novel and unique method named KIRnome for KIR typing from NGS data. KIRnome could determine KIR genotype accurately from WES and WGS data respectively. We expect KIRnome would facilitate revealation of immunogenetic facts in various disease. Moreover, future generation of KIR specific NGS data and improved reference sequence information of KIR would enable KIRnome to type KIR at allele level in a near future. Citation Format: Daeyoon Kim, Sung-Soo Yoon, Youngil Koh, Su Yeon Lee, Hongseok Yun, Sunghoon Cho, Hyung-Lae Kim. KIRnome: KIR genotyping for whole genome/exome sequencing data [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2582. doi:10.1158/1538-7445.AM2017-2582

Influence of Foam Morphology on Effective Properties Related to Metal Melt Filtration

In this article, a numerical study on the sensitivity, related to the performance of open‐cell foams used for the depth filtration of liquid metals, on two characteristic morphological properties is presented. Therefore, simulations of fluid flow and particle transport inside an artificial foam structure are carried out, whose porosity and strut shape is varied within a certain expected range. For comparison purposes, however, the simulations are also performed for three typical ceramic foam filters (CFF) with pore densities of 20 and 30 PPI, whose geometries are obtained from CT scans. In order to allow for a comparison between the different structures, a reference length is introduced that relies upon the actual ratio of pores per volume. The evaluation is mainly based on the comparison of the hydraulic tortuosity, the viscous and the inertial permeability coefficients as well as the initial filtration coefficient for alumina inclusions, with their size ranging from of 10 to 40 μm at process conditions typically encountered during the aluminum filtration. It is shown that the ratio of filtration coefficient and pressure drop increases with the porosity, while the material distribution between the struts and the joints is less influential. Finally, the article also provides information on the anisotropy of CFFs and on the transition behavior from steady to unsteady flow in open‐cell foams.

Compact Arrangements of Cable-Pulley Type Zero-Free-Length Springs

A methodology to develop springs with zero-free-length (ZFL) characteristics is presented, and the configurations for placing the springs precisely on the manipulators are introduced. A spring–string arrangement installed between two separate links of a serial-type manipulator is employed and is divided into three regions for mounting, tensioning, and placing the string. The springs can develop ZFL characteristics if adequate length is ensured for mounting the springs. To shorten the length for placing strings, a reference length acquired from the link configurations is utilized. The minimization of the placing length can therefore be described clearly. Because the overextended springs and links occupied the workspace of the other links as a result of the long mounting length, the springs are reorganized using pulleys and wire winding configurations to shorten the mounting length. The springs can then be arranged in alignment on the links. As achieved with this additional arrangement, comprehensive spring configurations on the manipulators can be shown. Two examples are presented after deriving the spring configurations for ZFL characteristics and the configurations with wire winding, respectively.

Multi-response optimization of crashworthiness parameters of bi-tubular structures

This article aims at presenting multi objective optimization of parameters that affect crashworthiness characteristics of bi-tubular structures using Taguchi method with grey relational analysis. To design the experiments, the <i>L</i>₉ orthogonal array has been used and based on that, the inner tubes have been fabricated by varying the three influence factors such as reference diameter, length difference and numbers of sides of the polygon with three levels, but all the outer cylinders have the same diameter and length 90 mm and 135 mm respectively. Then, the tailor made bi-tubular steel structures were subjected into quasi static axial compression. From the test results it is found that the crushing behaviors of bi-tubular structures with different combinations were fairly significant. The important responses (crashworthiness indicators) specific energy absorption and crush force efficiency have been evaluated from load - displacement curve. Finally optimal levels of parameters were identified using grey relational analysis, and significance of parameters was determined by analysis of variance. The optimum crashworthiness parameters are reference diameter 80 mm, length difference 0 mm and number of sides of polygon is 3, i.e., triangle within the selected nine bi-tube combinations.

Quantitative and Qualitative Evaluation of Sequence Patterns Found by Application of Different Educational Data Preprocessing Techniques

Educational data preprocessing from log files represents a time-consuming phase of the knowledge discovery process. It consists of data cleaning, user identification, session identification, and path completion phase. This paper attempts to identify phases, which are necessary in the case of preprocessing of educational data for further application of learning analytics methods. Since the sequential patterns analysis is considered suitable for estimating of discovered knowledge, this paper tries answering the question, which of these preprocessing phases has a significant impact on discovered knowledge in general, as well as in the meaning of quality and quantity of found sequence patterns. Therefore, several data preprocessing techniques for session identification and path completion were applied to prepare log files with different levels of data preprocessing. The results showed that the session identification technique using the reference length, calculated from the sitemap, had a significant impact on the quality of extracted sequence rules. The path completion technique had a significant impact only on the quantity of extracted sequence rules. The found results together with the results of the previous systematic research in educational data preprocessing can improve the automation of the educational data preprocessing phase as well as it can contribute to the development of learning analytics tools suitable for different groups of stakeholders engaged in the educational data mining research activities.

Prestretched airway smooth muscle response to length oscillation.

Airway smooth muscle (ASM) hyperconstriction is the cause of many respiratory diseases including asthma. In vitro testing has demonstrated that the active forces of ASM are reduced by length oscillation (LO) mimicking tidal breathing. In a previous study, we demonstrated that this force reduction can be further enhanced when superimposing oscillations (with certain frequencies and amplitudes) on this LO. In contrast, it has been reported that pressurizing the lung may help in relieving asthmatic airway constrictions. Ultimately, this pressurizing stretches the ASM and may disturb the acto‐myosin cross‐bridges in a manner similar to LO; however, it is of a static rather than dynamic nature. This research investigates the effect of combining both prestretch‐ and LO‐applications on contracted porcine ASM. Isolated porcine ASM relaxation was tested with a 0.56%, 2%, or 4% stretch of its reference length (L ref) in addition to LO. These oscillations are composed of a main wave mimicking the normal breathing (frequency of 0.33 Hz and amplitude of 4% L ref) and superimposed oscillations (frequencies of 20, 30, 40, 60 and 80 Hz and amplitude of 1% L ref). The oscillations were maintained for 10 min. The results demonstrate that a prestretch of 0.56% and 2% L ref does enhance the contracted ASM relaxation at certain superimposed length oscillations frequencies while of 4% L ref does not.

Determining the Parameters of Grinding Wheels Working Surface Profile

Based on mathematical and statistical processing of research experimental data defining the basic size of the abrasive tools working surfaces relief, as well as three-dimensional characteristics of the pore space, we identified the analytical dependences of these parameters on the grit, graininess, and structure of the instruments subject to the ways of their modernization and methods of fitting. We introduced a new concept of edge height of the working surface relief at which the matrix of grinding wheel crock comes onto the work surface. This allows comparatively analyze the parameters of the working surface profilogram in the wheels with different characteristics. This approach gives an opportunity to determine the average distance between grains, the relative reference length of profile, the size of surface pores and unevenness of grains at any level of the surface profile. It also allows justifying the function of structural characteristics of grinding wheels for specific conditions of grinding or, if necessary, selecting identical parameters of working surface of wheels with other characteristics to ensure the necessary operational parameters: productivity, machined surface roughness of parts and processing accuracy.

Optimizing Design of Two-dimensional Forging Preform by Bi-directional Evolutionary Structural Optimization Method

Abstract Preform is a step between blanking and finish forming. Design and optimization of the preform for forging would affect the material flow, forming load, dimension accuracy and tool wear. In this study, analysis, simulation and optimization process are carried out by utilizing MATLAB codes as well as using finite element analysis software (DEFORM-2D package) and CAD software as auxiliary tools. The results of this study are as following: using “Curve Fitting” method and two times of reference length are the better options for the boundary fitting method. Besides, the differences between using mean stress and normal pressure as an addition criterion were considered. In terms of strain, the average of effective strain is 0.643 and the standard deviation is 0.298 when using normal pressure as an addition criterion. These values are smaller than those using mean stress as an addition criterion, in which the values are 0.674 and 0.308, respectively. In terms of forming load, the value of the former is 70.616 tons. It is greater than value of the other criterion that forming load is 70.207 tons. Finally, in terms of shape, the results from normal pressure are more complex than those from mean stress.

An Efficient Path Completion Technique based on Auxiliary Pages for Web Usage Mining

The frequent usage of website access the wide range of information in the internet world. There is a need of system to handle the web usage data efficiently. The preprocessing data is further used for knowledge discovery process. The data preprocessing system for web usage mining gives a new approach to the user with the help of path completion algorithm. The user session identification algorithm is also implemented to automatically append the user data and the missing pages of the user access paths are also identified and added using the referrer-based method which resolves the problems facing by proxy server and local caching. Maximal forward reference and reference algorithms are considered as a solution for the average reference length of the auxiliary pages which is estimated in advance. Web access log are used to retrieve data from the server which is generated by the client whenever the request is made. By using the proposed path completion algorithm with the web access log, it efficiently appends the lost information of the visitor and the reliability of the access data also shows better improvement.

High-Throughput Next-Generation Sequencing of Polioviruses.

The poliovirus (PV) is currently targeted for worldwide eradication and containment. Sanger-based sequencing of the viral protein 1 (VP1) capsid region is currently the standard method for PV surveillance. However, the whole-genome sequence is sometimes needed for higher resolution global surveillance. In this study, we optimized whole-genome sequencing protocols for poliovirus isolates and FTA cards using next-generation sequencing (NGS), aiming for high sequence coverage, efficiency, and throughput. We found that DNase treatment of poliovirus RNA followed by random reverse transcription (RT), amplification, and the use of the Nextera XT DNA library preparation kit produced significantly better results than other preparations. The average viral reads per total reads, a measurement of efficiency, was as high as 84.2% ± 15.6%. PV genomes covering >99 to 100% of the reference length were obtained and validated with Sanger sequencing. A total of 52 PV genomes were generated, multiplexing as many as 64 samples in a single Illumina MiSeq run. This high-throughput, sequence-independent NGS approach facilitated the detection of a diverse range of PVs, especially for those in vaccine-derived polioviruses (VDPV), circulating VDPV, or immunodeficiency-related VDPV. In contrast to results from previous studies on other viruses, our results showed that filtration and nuclease treatment did not discernibly increase the sequencing efficiency of PV isolates. However, DNase treatment after nucleic acid extraction to remove host DNA significantly improved the sequencing results. This NGS method has been successfully implemented to generate PV genomes for molecular epidemiology of the most recent PV isolates. Additionally, the ability to obtain full PV genomes from FTA cards will aid in facilitating global poliovirus surveillance.

Scaling Laws for the Peak Overpressure of a Cannon Blast

For large cannons, blast overpressure can have a detrimental effect on the crew in the near field (i.e., within a distance of 50 tube diameters or calibers from the muzzle center) as well as on the support personnel and equipment in the far field (i.e., at a distance greater than 50 calibers). Therefore, an efficient method to determine the peak overpressure due to a cannon blast is highly desired. In this study, we investigate scaling laws for the peak overpressure, due to the primary blast of a large cannon, with the aim that they can be applied as an efficient method to evaluate the peak overpressure in the far field. We explore two types of scaling laws; each type is based on a power-law model involving a prefactor and an exponent as model parameters. The two types of the power-law models differ in the way they incorporate the polar angle dependence. The first type was proposed by Fansler and Schmidt (1983, “The Prediction of Gun Muzzle Blast Properties Utilizing Scaling,” U.S. Army Ballistic Research Laboratory, Aberdeen Proving Ground, MD, Report No. ARBRL-TR-02504). They developed a muzzle-center based scaling law (MCSL) in which the polar angle dependence was incorporated through a reference length scale to define a nondimensional or scaled radial distance from the muzzle center and the model parameters were independent of the polar angle. They calibrated the parameters by employing least-squares fit to a wide range of experimental data. In this study, we recalibrated or updated the parameters for the current cannon by using the numerical simulation data for the cannon blast in the near field. Additionally, we developed a second type of scaling law in which the radial distance is defined from the blast center (in contrast to the muzzle center) and scaled using the inner tube diameter. In this model, the angular dependence is incorporated directly into the model parameters. For this model too, we calibrated the parameters by using the numerical simulation data. We observe that both the modified version of the muzzle-center based scaling law as well as the blast-center based scaling law (BCSL) show a significantly closer fit to the numerical and experimental data and achieve a similar level of accuracy. This indicates that the current form or structure of the two types of power-law based scaling models is able to fit well with the near-field data; however, the current methodology requires a calibration process for a given cannon of interest. In the future, with far field data, we plan to evaluate predictions in the far field.

On the Safety of the European Stability Design Rules for Steel Members

The European stability design rules for steel columns, beams and beam-columns are classically based on Ayrton-Perry formulations that rely on the calibration of imperfection factors in order to estimate the maximum resistance. More recently, “general approaches” have been proposed that combine in-plane and out-of-plane behaviour based on a single reference length. The safety of design rules in modern codes of practice is based on the use of partial factors and the separation of the uncertainty related to loading and resistance. EN 1990 - Annex D [1], for example, contains a procedure for the safety analysis of resistance functions, based on First-Order Reliability Methods. However, its application to stability design rules is not straightforward and several additional assumptions are necessary to ensure that a target probability failure is achieved. Finally, design rules and its accuracy depend on the accuracy of the relevant basic variables such as material properties, geometric properties and imperfections. It is therefore required to appropriately characterize the statistical distributions of these basic variables in order to comply with the (semi-) probabilistic safety level assessment of design rules. This paper discusses the different approaches for the derivation of design rules for columns, beams and beam-columns and proposes a mechanical consistent general approach. Secondly, a consistent procedure for the probabilistic assessment of the safety level of stability design rules is presented that simplifies the way material and geometrical properties are considered while maintaining its statistical relevance.

Corrections to “Realization and Performance of an All-Polymer Optical Planar Deformation Sensor” [Dec 15 7029-7035

In the above paper [1] , in paragraph III, for a displacement of 6 $ {\mu }\text{m}$ over a reference length of 100 $ {\mu }\text{m}$ , the corresponding strain was mistakenly reported with 60 $ {\mu } \epsilon $ . The correct value is 60 $\text{m}\epsilon $ .

Analysis of hydrodynamics of a moving trawl codend and its fluttering motions in flume tank

The coupled dynamics of the codend fluttering motion and its hydrodynamics behavior are investigated based on PIV measurements carried out around a 1/10 scaled model codend. The mean wake flow characteristics are firstly analyzed demonstrating the great effect of the codend motion. The differences in flow contour between fluttering motion and no-fluttering codend are highlighted by analyzing the classical mean characteristics of a body wake flow. In presence of fluttering motion, the classical results are recovered only if one considers the vertical extent of the codends oscillations as a reference length scale. Secondly, the frequency content of codend oscillations is analyzed and it is linked to the physical mechanisms. It is observed that the motion of the codend is mainly of a low-frequency activity and of another component related to the vortex shedding street. A complex fluid–structure interaction is then demonstrated where the near wake hydrodynamics of the moving codend structure are an intricate interplay between the codend fluttering motion and the shear layer instabilities and large scale vortex shedding. The knowledge of such flow instabilities is of great importance to improve the understanding of the force acting on a trawl and for the implementation of some selected device to drive fish near the codend and then to reduce juvenile by-catch.

On optimizing the basic geometry of hypoid gears

By the help of dual numbers and vectors, an intrinsic parametric representation of the Plücker conoid is derived that is the ruled surface consisting of all composite screw axes generated by two given skew screws. In the field of gearing an application results in the design of pitch surfaces of a double screw gearing and especially of hypoid gears. For basic geometric dimensions parametric representations are derived concerning pitch cones, contact normal, spiral angles, limit pressure angles, sliding velocity deviation, friction loss, and efficiency. These magnitudes simply depend on the introduced reference angle and length as variables. For hypoid gears, the paper shows that the free optimization problems for the absolute value of the composite relative velocity, the friction loss coefficient, and the theoretical efficiency are uniquely solvable. As an example for a constraint optimization problem the degree of mesh overlap is considered. Finally, the free optimization of weighted axial and radial forces at the pinion of a hypoid gear is solved.

Development of a computer program for aerodrome movement area facilities planning and design standards

The planning and design of an airport is subject to many difficulties. One of these difficulties stems from uncertainty about the future demands of air traffic evolution. The growth of and change of potential air traffic impact significantly on airport facilities development. Current airport development paradigms seem inadequate to deal with the volatility of air traffic and site conditions. To overcome this dilemma, variables such as the characteristics of airport movement area parts and aircraft, as well as site conditions, have been extensively examined. Then analytical models based on the fleet mix of aircraft type selection and site conditions have been formulated. The main parameters considered in the analytical models are critical design, aircraft, site information and the reference code of the airport. Depending on these parameters and analytical models, a framework for computerised simulation software has been developed. The developed simulation software combines several types of model with different capabilities and features. The objective of these models is to reach an optimum analysis for the planning and design of airport facilities with the greatest degree of flexibility and expansibility. The newly created models are used to determine runway turn pad dimensions, runway exit locations, taxiway fillet and widening dimensions, apron size, visual marking, PAPI sitting distance, firefighting facilities and airspace obstacle limitations for all sizes and types of airport. The improved models can also be used to determine aeroplane reference length and its adjustments as well as the physical characteristics of movement areas. A sample empirical exercise was carried out to verify the benefits obtained from the proposed models. A comparison between the outcomes of this approach and previous methodologies proves the reliability and effectiveness of this technique. Practically, the analysis and calculation result derived from the program models was used to supplement three supporting case studies. In the first case study, the sitting distances of visual aid devices fixed on the runway approaches at five international airports are analysed and assessed. In the second case study, the cumulative usage and landing segments of runway turn-off points was drawn from interactions among the various approach speeds of the different studied aircrafts. The last case study provides the geometrical design charts of taxiway intersection widening portions for different aeroplane groups and manoeuvring systems. The developed planning and design program can be regarded as an alternative supporting tool applied to a variety of airports and aeroplanes.

Neuromuscular structure of the tibialis anterior muscle for functional electrical stimulation.

This study describes the nerve entry points and intramuscular nerve branching of the tibialis anterior, providing essential information for therapeutic functional electrical stimulation and botulinum toxin injection. One hundred and ten legs from Korean and Thai cadavers were dissected. Ten specimens were harvested and subjected to modified Sihler's staining. The average total length from the lateral malleolus to the fibular head was 32.0cm (SD 1.9). The nerve entry points were densely distributed between 86.5 and 90.6% of the reference length, where the first and second nerve entry points were observable. A densely arborizing area of the intramuscular nerve branches was observed at 70-80% of the reference length. Based on the results of this study, clinicians can increase the effectiveness of therapeutic functional electrical stimulation and identify the ideal sites for botulinum toxin injection to the tibialis anterior muscle.

The role of sarcomere length non-uniformities in residual force enhancement of skeletal muscle myofibrils.

The sarcomere length non-uniformity theory (SLNT) is a widely accepted explanation for residual force enhancement (RFE). RFE is the increase in steady-state isometric force following active muscle stretching. The SLNT predicts that active stretching of a muscle causes sarcomere lengths (SL) to become non-uniform, with some sarcomeres stretched beyond actin–myosin filament overlap (popping), causing RFE. Despite being widely known, this theory has never been directly tested. We performed experiments on isolated rabbit muscle myofibrils (n = 12) comparing SL non-uniformities for purely isometric reference contractions (I-state) and contractions following active stretch producing RFE (FE-state). Myofibrils were activated isometrically along the descending limb of the force–length relationship (mean ± 1 standard deviation (SD) = 2.8 ± 0.3 µm sarcomere−1). Once the I-state was reached, myofibrils were shortened to an SL on the plateau of the force–length relationship (2.4 µm sarcomere−1), and then were actively stretched to the reference length (2.9 ± 0.3 µm sarcomere−1). We observed RFE in all myofibrils (39 ± 15%), and saw varying amounts of non-uniformity (1 SD = 0.9 ± 0.5 µm) that was not significantly correlated with the amount of RFE, but through pairwise comparisons was found to be significantly greater than the non-uniformity measured for the I-state (0.7 ± 0.4 µm). Three myofibrils exhibited no increase in non-uniformity. Active stretching was accompanied by sarcomere popping in four myofibrils, and seven had popped sarcomeres in the I-state. These results suggest that, while non-uniformities are present with RFE, they are also present in the I-state. Furthermore, non-uniformity is not associated with the magnitude of RFE, and myofibrils that had no increase in non-uniformity with stretch still showed normal RFE. Therefore, it appears that SL non-uniformity is a normal associate of muscle contraction, but does not contribute to RFE following active stretching of isolated skeletal muscle myofibrils.

Computed tomography evaluation of the iliac crest apophysis: age estimation in living individuals.

Determination of the ossification properties of the iliac apophysis is important not only in the clinical evaluation of patients undergoing orthopedic surgery but also in age estimation studies for forensic purposes. The literature includes both anthropological and radiological (conventional radiography, ultrasonography, and magnetic resonance imaging modalities) investigations of the different staging systems used for these purposes. In this study, we assessed the utility of computed tomography (CT) of the iliac crest apophysis in estimating forensic age. CT scans of the iliac crest apophysis of 380 patients (187 females, 193 males, and 10-29years of age) were evaluated according to the four-stage system. Further subclassification did not give data properly due to the reference length measurement of the iliac wing with CT. Thus, in our series, stage 2 was first seen in 12years of age and stage 3 in those 14years of age in both sexes and on both sides of the pelvis. Stage 4 was first seen in 17years of both sexes but only on the right side; on the left side, it appeared in females 18years of age and in males 17years of age. Present data was found consistent with previous pelvic radiographic findings. First seen ages for stage 2 and 3 are 12 and 14years respectively which presented valuable information for legally important age thresholds. However, disadvantages of CT, including high-dose radiation exposure to gonads, the difficulty of evaluating the iliac crest, and the age boundary of 17years, could make this method infeasible, as compared with hand wrist and pelvic radiographic methods. CT of the iliac crest has probably a greater utility where preexisting CT scans of the pelvic region are available, and it may be considered as a supportive method for age-estimation purposes.