Horizontal Geometry Research Articles

Drifting in a Global Space of Textile Flows: Apparel Bazaars in Poland's Łódź Region

This paper examines the influence of globalization and the circulation of money, goods and people on the functioning of post-socialist apparel bazaars in Poland's Łódź region. The theoretical backbone of the study is presented first, followed by an introduction to the general phenomenon of the bazaar. The following sections then address the temporal, spatial and institutional contexts of the development of the Łódź region's textile industry, and how the more recent opportunities, constraints and threats of globalization have been perceived and maintained by key players at the PTAK Bazaar. We argue that local economic development, in which the bazaar plays a crucial role, is scale-dependent. No longer the subject of a topo-cratic, hierarchical policy as it was under the socialist regime, current performance is the result of both vertical and horizontal power geometries.

Fuel-Efficient Formation Flight-Control Design Based on Energy Maneuverability

This paper addresses the fuel saving problem of the follower aircraft in the loose leaderfollower formation flight in which the lateral separation between formation members is more than a wingspan of the leader aircraft. This formation geometry offers no drag benefit, but has a strategic advantage. In the case of loose formation flight, the follower aircraft usually consumes more fuel than the leader aircraft because the follower aircraft should use more thrust to maintain given formation geometry, especially during the turning phase from the outside of the leader’s flight path or join-up phase. A fuel efficient formation control scheme based on the energy maneuverability is proposed in this paper. To design the proposed control law, the velocity command is designed using feedback linearization for the horizontal formation geometry and then coverts it to the altitude command using the energy equation. Also, the fuel consumption analysis is performed. Numerical simulation is performed to verify the effectiveness of the proposed controller.

Behaviour of piles and pile groups in marine clay under compressive load at various stress conditions

Experimental investigations on model single piles, line pile groups (2 X 1) and square pile groups (2 X 2) subjected to axial compressive load were conducted in a specially designed triaxial cell with enlarged dimensions in marine clay at vertical and horizontal stress conditions. The variables used in this experiments were embedment length to diameter ratio (L/D = 8.93, L/D = 17.5), spacing of piles in a group (4D, 5D, 6D), controlled horizontal (σH), vertical (σV) stresses (0.03 N/mm² and 0.06 N/mm²) and pile group geometry / configuration. Parametric study on the influence of the variables involved has been carried out on the load displacement response, tip, shaft, and total resistance and group efficiency of the pile groups. A statistical regression model, based on experimental results, is used to study the variation of efficiency of pile groups with spacing under different vertical and horizontal stress conditions.

UAV Formation Wight Control Law Utilizing Energy Maneuverability

This paper deals with the energy saving problem of the follower aircraft in the loose leader-follower formation geometry in which the lateral separation between formation members is more than a wingspan of the leader aircraft. This formation geometry offers no drag benefit, but has a strategic advantage. In the case of loose formation flight, the follower aircraft usually consumes more energy than the leader aircraft because the follower aircraft should use more thrust to maintain given formation geometry, especially during the turning phase from the outside of the leader"s flight path or join-up phase. A formation control scheme based on the energy maneuverability is proposed in this paper. To design the proposed control law, the velocity command is designed using feedback linearization for the horizontal formation geometry and then coverts it to the altitude command using the energy equation. Numerical simulation is performed to verify the effectiveness of the proposed controller.

Atmospheric-pressure metalorganic vapour phase epitaxy optimization of GaAsBi alloy

Metalorganic vapour phase epitaxial growth of GaAsBi alloy has been carried out at atmospheric pressure in horizontal geometry reactor. In order to achieve the growth of this alloy, we have investigated the growth conditions which allow epitaxial layers of a good crystalline quality with a maximum bismuth concentration. Growth parameters such as growth temperature, trimethylbismuth (TMBi) flow and V/III ratio were checked on a wide range. Growth temperature was varied between 365 and 450 °C, TMBi flow was checked in the range below 2 µmol/min and V/III ratio was varied between 6 and 20. According to our experimental results based on in-situ reflectivity measurements, scanning electron microscopy observations and high resolution X-ray diffraction analysis, it was found that the maximum Bi concentration reached in GaAs 1 − x Bi x layers was 3.7%. This maximum, relative to atmospheric-pressure metalorganic vapour phase epitaxy technique, was found under a growth temperature of 420 °C, a TMBi flow of 0.2 µmol/min and a V/III ratio of 9.5.

Ｊ‐ＰＡＲＣで迎える結晶学の新展開 １．Ｊ‐ＰＡＲＣで展開される中性子科学 水平型反射率計の概要と界面構造科学

Neutron reflectometry is a very powerful and essential technique for structural studies on material interface with high depth resolution. Currently, a neutron reflectometer with horizontal sample geometry is being constructed on one of the neutron beam lines at a high-intensity pulsed-neutron source of Material and Life Science Facility, the Japan Proton Accelerator Research Complex (J-PARC), though it is not fully funded yet. The large gain in neutron flux at the J-PARC makes time-resolved reflectivity measurements of the order of minutes or even shorter, and also weak off-specular scattering measurements possible. The reflectometer will be equipped with state-of-the-art neutron optics, a position-sensitive detector with high counting rate and high spatial resolution, and a polarized neutron handling system. It will also have a grazingincidence small-angle scattering option to observe non-layered structures, and a neutron spin-echo option to directly probe interfacial dynamics in the order of neV. Much progress is expected in understanding the interfacial phenomena or interfacial functions by using the J-PARC neutron reflectometer.

A simple and efficient locally mass conserving semi-Lagrangian transport scheme

A new simple and accurate locally mass conserving semi-Lagrangian (LMCSL) scheme has been constructed. Mass conservation is obtained by introducing modified interpolation weights at the upstream departure points. Thereby the total mass given off by a given Eulerian grid point to all the surrounding semi-Lagrangian (SL) departure points is equal to the cell area represented by that grid point. The new scheme is equivalent to the cell-integrated semi-Lagrangian (CISL) transport schemes in the sense that divergence—via the weights—is determined by the trajectories and not by centred differences as in traditional SL-schemes.The LMCSL scheme has been combined with the semi-implicit scheme in a shallow water model. Thereby a numerically stable and inherently mass conserving scheme permitting long time steps has been set up. Tests in plane horizontal geometry including topography give solutions very similar to those obtained with the traditional semi-implicit SL scheme. The well known mountain wave resonance problem appears to be reduced.The increase in numerical cost of the new scheme relative to traditional SL models is small, particularly when there are several passive tracers, since the same weights are used for all tracers.

Influence of technological conditions on electronic transitions in chemical vapor deposited poly(azomethine) thin films

Thin films of poly(1,4-phenylenemethilidynenitrilo-1,4-phenylenenitrilomethilidyne) (PPI) have been prepared by chemical vapor deposition in the horizontal geometry using gaseous argon as a transport agent. PPI thin films have been grown by polycondensation of para-phenylene diamine (PPDA) and terephtal aldehyde (TPA). Fourier Transform Infrared spectra confirm formation of PPI layers without end groups. The strongest absorption band with discernible vibronic progression has been found to be due to superposition of 2.64, 2.82 and 3.03 eV bands corresponding to interband transitions connecting electronic ground state and vibrational levels of electronic excited state. A feature seen at about 2.6 eV in the spectra of PPI films prepared at higher temperatures of PPDA and TPA sources are attributed to excitons connected with the π–π⁎ gap. Shoulder at 3.31 eV is attributed to interband transitions between delocalized states, while a peak at 4.2 eV is attributed to excitons formed by localized holes and delocalized electrons and vice versa and interband transitions connecting delocalized and localized bands, with the binding energy of about 0.8 eV. Thin films prepared at low temperatures of monomers consist of randomly distributed PPI chains weakly bound together.

Instream restoration: its effects on lateral stream–subsurface water exchange in urban and agricultural streams in Southern Ontario

AbstractInstream restoration strategies do not generally consider the subsurface environment. The study of recently restored stream reaches can provide an opportunity to assess the impacts of restoration on surface–subsurface exchange. In this study, lateral hyporheic zones occurring in a constructed gravel bar and re‐meandered stream reach were examined, using hydrometric data in combination with differences in background conservative ion and tracer injection experiments. Both the constructed gravel bar and the meander bends induced lateral hyporheic exchange flow. In the gravel bar, lateral hyporheic exchange increased after a riffle‐pool sequence was constructed in the channel adjacent to the bar. The substrate in the meander bends had low saturated hydraulic conductivity, and the stream–subsurface exchange was limited despite the large change in channel configuration. These results suggest that to enhance and maintain stream–subsurface water exchanges, restoration projects that modify horizontal geometry should involve construction of vertical morphologic features, and where floodplain sediments are fine‐grained, the addition of coarse sediments should also be incorporated in the design. Copyright © 2007 John Wiley & Sons, Ltd.

Model reliability for 3D electrical resistivity tomography: Application of the volume of investigation index to a time-lapse monitoring experiment

Solution appraisal is difficult for large 3D, nonlinear inverse problems such as electrical resistivity tomography (ERT). We construct the volume of investigation index (VOI) as the sensitivity of the inversion result to a variable-reference model. This limited exploration of the model space provides an efficient and pragmatic method of appraisal for a particular data set and a 3D model domain. We present a synthetic example to demonstrate the applicability of the VOI as a tool for characterizing model reliability for 3D ERT and as a method of survey design. We show how the VOI provides a measure of model resolution and how insight gained from VOI analysis cannot be gained through similar examination of the average sensitivity distributions. In the context of ERT monitoring of an injection/withdrawal experiment, we utilize the VOI for judging the degree of reliability of hydrogeological interpretations that stem from features observed in the estimated electrical-conductivity models. We employ the VOI for the experimental data as a comparative measure of survey performance. For this experiment, the VOI shows that a larger, more artifact-free region of reliability is achieved using a circulating vertical dipole-dipole survey geometry, as opposed to a horizontal dipole-dipole survey geometry. The experimental VOI distributions exhibit dependence on the borehole infrastructure and the actual earth model.

Flammability of combustible materials in reduced oxygen environment

Flammability of combustible materials in reduced oxygen environment is studied using theoretical analysis and laboratory-scale experiments. The experimental results show that the limiting oxygen concentration (LOC) at extinction and re-ignition can be measured using a variable oxygen concentration technique with uncertainties of ±0.5% (vol.). The imposed external radiant heat flux only affects the LOC measurements for the fuels tested in this work when the flux is less than 30 kW/m 2. Comparison of measured LOCs in parallel panel and horizontal geometries suggests that the latter appear to be more conservative given the same total incident heat flux to the fuel surface. A validation parallel panel test for fire propagation using PMMA at 15% (vol.) oxygen concentration confirmed fire propagation when the ambient oxygen concentration is higher than, but approaching the measured LOC. LOC calculations using critical flame temperature and Spalding's B-number theory provide qualitative agreement with the experimental data. However, quantitative comparison of calculations and measurements shows that the calculated LOCs are sensitive to the selection of flame temperature. Furthermore, calculations also show that LOCs do not change significantly if the ambient temperature varies no more than 40 K. Based on the experimental results, most of the combustible materials studied in this work such as polyethylene, oak and corrugated paper board will not be adequately protected if the ambient oxygen is maintained at 15% (vol.) or higher.

A generalized mathematical description for comparative assessment of various horizontal polar tube geometries with regard to external film condensation in presence of non-condensable gases

A generalized mathematical treatment is postulated to investigate the condensation heat transfer performance of horizontal tubes with varying geometries, with the presence of non-condensable gases in the free stream. The governing equations of mass, momentum and energy conservation in the liquid phase are solved semi-analytically, with matching constraints being imposed at the liquid–vapour interface, while the governing equations of energy and species conservation in the vapour phase are solved numerically. An air–water vapour system is considered for demonstrating the mathematical model. Special cases of the model are illustrated with the aid of elliptical and equiangular spiral geometries. It is revealed that the geometrical features of typical polar surfaces can turn out to be favourable in arresting probable drastic reductions in the condensation heat transfer rates that could be otherwise associated with the presence of non-condensable gases in the free stream. The favourable effects induced by polar surfaces become relatively more prominent, as percentage of non-condensable gases in the free stream increases. A geometrical shape function is also ascertained in this regard, which quantifies the extent of this augmentation in the heat transfer performance. In general, it is suggested that polar surfaces with higher values of the shape function over a majority of the azimuthal regime can turn out to be more desired choices for achieving enhanced rates of condensation heat transfer, provided that there are no serious manufacturability constraints.

Width of a ferrofluid finger: Hysteresis and a double energy minimum

We study a ferrofluid in a horizontal Hele-Shaw geometry subjected to a vertical magnetic field. Specifically, we calculate the energy of a single ferrofluid finger using an idealized model for the finger. By minimizing this energy, we find the preferred finger width as a function of the applied field. Our model predicts a first order transition as the fluid abruptly transforms from a circular drop to a finite finger. This behavior arises because of a double energy minimum that yields two different stable configurations for the system. Interestingly, this system exhibits hysteresis as the circle-to-finger (increasing field) transition occurs at a different applied field than the finger-to-circle (decreasing field) transition. We carry out a simple experiment and observe good overall agreement with the theoretical predictions.

A Revised Prescription for the Tayler‐Spruit Dynamo: Magnetic Angular Momentum Transport in Stars

Angular momentum transport by internal magnetic fields is an important ingredient for stellar interior models. In this paper we critically examine the basic heuristic assumptions in the model of the Tayler-Spruit dynamo, which describes how a pinch-type instability of a toroidal magnetic field in differentially rotating stellar radiative zones may result in large-scale fluid motion. We agree with prior published work both on the existence of the instability and its nearly horizontal geometry for perturbations. However, the approximations in the original Acheson dispersion relation are valid only for small length scales, and we disagree that the dispersion relation can be extrapolated to horizontal length scales of order the radius of the star. We contend that dynamical effects, in particular, angular momentum conservation, limit the maximum horizontal length scale. We therefore present transport coefficients for chemical mixing and angular momentum redistribution by magnetic torques that are significantly different from previous published values. The new magnetic viscosity is reduced by 2-3 orders of magnitude compared to the old one, and we find that magnetic angular momentum transport by this mechanism is very sensitive to gradients in the mean molecular weight. The revised coefficients are more compatible with empirical constraints on the timescale of core-envelope coupling in young stars than the previous ones. However, solar models including only this mechanism possess a rapidly rotating core, in contradiction with helioseismic data. Previous studies had found strong core-envelope coupling, both for solar models and for the cores of massive evolved stars. We conclude that the Tayler-Spruit mechanism may be important for envelope angular momentum transport but that some other process must be responsible for efficient spin-down of stellar cores.

The HANARO neutron reflectometer with horizontal sample geometry; engineering designs and performance simulation

A new neutron reflectometer with a horizontal sample geometry was designed and is now under construction at the HANARO, 30 MW research reactor. It was originally built and operated at the H9-A beam port at BNL, and was relocated to HANARO in 2004. We performed simulations of neutron ray-tracing to evaluate the performance of all of the optical components of the instrument with a Monte Carlo technique using McStas code. The feasible wavelength of the incident neutron beam is 2.52 Å. It produces a q-range up to 0.126 Å − 1 with a supermirror as a deflector. Our studies indicated possibilities to improve the performance of the guide tube. Although the performance is limited (limited q-range and flux due to multiple reflections prior to the deflector), it promises to be the first reflectometer in Korea for the study of free surfaces, which is currently in demand.

Instabilities in vertically vibrated fluid-grain systems

When a bed of fluid-immersed fine grains is exposed to vertical vibration a wealth of phenomena may be observed. At low frequencies a horizontal bed geometry is generally unstable and the bed breaks spatial symmetry, acquiring a tilt. At the same time it undergoes asymmetric granular convection. Fine binary mixtures may separate completely into layers or patterns of stripes. The separated regions may exhibit instabilities in which they undergo wave-like motion or exhibit quasi-periodic oscillations. We briefly review these and a number of related behaviours, identifying the physical mechanisms behind each. Finally, we discuss the magneto-vibratory separation of binary mixtures which results from exposing each component to a different effective gravity and describe the influence of a background fluid on this process.

Monitoring lateral track irregularity from in-service railway vehicles

Maintaining the alignment of railway track is vitally important for the smooth and safe passage of railway vehicles. Poor track alignment can result in poor ride quality, flange contact, or even flange climb. Accurate horizontal track geometry can be measured using a dedicated track recording vehicle or from a full track geometry recording system mounted on an in-service vehicle. This paper describes the use of sensors mounted on the bogie of an in-service vehicle to estimate the mean track alignment without the use of optical or contact sensors. In principle, either bogie lateral acceleration or yaw rate can be processed to give an estimate of mean lateral track irregularity, but a yaw rate gyro provides consistent estimates down to lower vehicle speeds than does an accelerometer and does not require compensation for the effects of bogie roll. An improved estimate can be obtained by inverting the dynamic relationship between the mean track alignment and the bogie yaw motion. This is demonstrated with results from a Class 175 vehicle. Continually monitoring the lateral response of a bogie on an in-service vehicle, using only a yaw rate gyro, can provide data enabling the prioritization of maintenance operations.

Anisotropy, cracking, and shrinkage of vertisol samples Experimental study and shrinkage modeling

Measuring and modelling the soil shrinkage curve (ShC) has generated increased interest, but uncertainty in shrinkage curve parameters has not been documented, and the most recent models have not been compared. This study was performed on 11 core samples collected in the same horizon of a vertisol. The objectives of the study were to (i) characterize the anisotropy of soil samples shrinkage by comparison of vertical, horizontal and volume shrinkage, (ii) analyse the impact of shrinkage anisotropy on fitted shrinkage parameters, (iii) determine uncertainty in shrinkage parameters, and (iv) compare the plasma pore volume as modelled by the clay-paste model (CP) to the plasma pore volume as estimated with the soil shrinkage XP model. The coefficients of variation of the different ShC parameters were smaller than 12% and 3% for water contents and volumes, respectively. Cracking led us to exclude some vertical ShC for XP model fitting, as the ShC departed strongly from the S-Shape model. The vertical geometry factor was smaller than 3 and the horizontal geometry factor was larger than 3 in average. The geometry factor values were changing with water content; they deviated widely from 3 at water saturation, but remained constant and close to 3 in between air entry (AE) and maximum swelling (MS). Cracking and anisotropy had no impact on the XP fitted shrinkage parameters. They were not significantly different between one-dimensional (1-D) and volume measurements. The results of our study suggest that parameters from 1-D shrinkage might be adequate to describe three-dimensional shrinkage. The XP plasma pore volumes at shrinkage limit (SL) were in the range of mercury porosimetry values, the average fitted plasma volume was only 1.7% larger than the median measured value. Direct calibration of CP model from independently measured parameters gave water contents at SL and AE one order of magnitude smaller and two times larger than the fitted values, respectively. But when the AE point water content was set equal in the CP and the XP model, the two modelled plasma ShC were almost identical, with differences depending only on the small difference between fitted and measured plasma volume at SL. Thus, the CP model could be used instead of XP-plasma model to describe the plasma ShC, provided that AE points were identical. This is, however, contradictory with the proposed independent calibration method. The present results are encouraging regarding ShC determination and the comparability of shrinkage modelling approaches. Further comparison of the models requires additional experimental information on the soil plasma shrinkage, especially on MS point.

Magma emplacement in transpression: The Santa Olalla Igneous Complex (Ossa-Morena Zone, SW Iberia)

The Santa Olalla Igneous Complex, a late-Variscan group of intrusions located in the Ossa-Morena Zone (SW Iberia), has been the focus of a gravity and structural study. The structure outlined by the foliation map is complex, showing two different structural domains: one characterized by vertical, and the other by horizontal, magmatic foliations. The vertical fabrics are restricted to the NE half of the complex, which is in direct contact with a Variscan sinistral strike-slip fault (Cherneca fault) whereas the horizontal fabrics are developed in the SW half of the complex, which is characterized by a horizontal tabular geometry. Gravity modeling indicates that the deeper floor of the plutons is closely related to the NE margin and the Cherneca fault. An emplacement and structural evolution model for this igneous complex is proposed following these structural and gravity results: (1) magma ascent was favored by releasing bends in the trace of the Cherneca fault; (2) when magma reached the present level it intruded to the SW with a horizontal sheet geometry generating the subhorizontal foliation domain; (3) after emplacement, the NE half of the complex suffered the external tectonic stress field provoked by sinistral motion along the Cherneca fault, subsequently generating the subvertical magmatic foliation domain.

The HANARO neutron reflectometer with horizontal sample geometry. Relocation and upgrade plans of the BNL H9-A reflectometer

A new neutron reflectometer with horizontal sample geometry is under construction at a thermal neutron port at HANARO, the 30 MW research reactor at KAERI. It was originally designed and operated at the H9-A beam port at Brookhaven National Laboratory (BNL), and was relocated to HANARO in 2004. It will be initially installed at the ST3 thermal-neutron port without any significant modification, and significant improvements in structure and performance are planned when the new cold source is installed in 2008. If successfully installed, it will be the first reflectometer in Korea for the study of free surfaces, which is currently lacking. For the thermal source, the feasible wavelength of incident neutron beam is 2.5 Å and this would permits the q ranges up to 0.21 Å −1.