Horizontal Gap Research Articles

Horizontal roof gap of backfill hydraulic support

For the backfill hydraulic support as the key equipment for achieving integration of backfilling and coal mining simultaneously in the practical process, its characteristics will directly influence the backfill body’s compression ratio. Horizontal roof gap, as a key parameter of backfilling characteristics, may impact the backfilling effect from the aspects of control of roof subsidence in advance, support stress, backfilling process and the support design. Firstly, the reason why horizontal roof gap exists was analyzed and its definition, causes and connotation were introduced, then adopting the Pro/E 3D simulation software, three typical 3D entity models of backfill hydraulic supports were built, based on the influence of horizontal roof gap on backfilling effect, and influence rules of four factors, i.e. support height, suspension height, suspension angle and tamping angle, were emphatically analyzed on horizontal roof gap. The results indicate that, the four factors all have significant impacts on horizontal roof gap, but show differences in influence trend and degree, showing negative linear correlation, positive linear correlation, positive semi-parabolic correlation and negative semi-parabolic correlation, respectively. Four legs type is the most adaptive to the four factors, while six legs (II) type has the poorest adaptability, and the horizontal roof gap is small under large support height, small suspension height, small suspension angle and large tamping angle situation. By means of optimizing structure components and their positional relation and suspension height of backfill scrape conveyor in the process of support design and through controlling working face deployment, roof subsidence in advance, mining height and backfilling during engineering application, the horizontal roof gap is optimized. The research results can be served as theoretical basis for support design and guidance for backfill support to have better performance in backfilling.

Efficiency Evaluation of Osteopathic Treatment of Primary School Children with Mesial Bite

One of the main dentistry problems is the prophylaxis and treatment of dentofacial anomalies and deformities. Different forms of progenia (lower macrognathia, mandibular protraction, mesial bite) are the most common defects according to the number of patient requests, the complexity of clinical presentation, the frequency of relapses and treatment failures. The article describes osteopathic treatment effect in complex therapy of primary school children with mesial bite. The osteopathic status of the patients was characterized. The study showed the osteopathic treatment efficiency which is proved by the normalization of nasal breathing, swallowing, tongue functions and the rapidly decreasing horizontal gap between teeth

Investigating ramp gradients for humps on railway platforms

Horizontal and vertical gaps between the train and the platform are a major safety concern for railway passengers, especially for disabled passengers. London Underground is implementing a programme to install platform humps to remove vertical differences between the train and the platform. In order to properly design platform humps, this study empirically investigated the effects of the design factors of the ramps, namely the slope and cross-fall gradients, on disabled passengers. The investigation consisted of two experiments: one where 20 participants were asked to walk on simulated slopes, and the other where 25 participants were asked to board or alight from the simulated train from or onto the slopes. The slope gradients tested were 3·0% (1:33), 5·2% (1:19) and 6·9% (1:14) with the cross-fall gradients 1·5% (1:67), 2·0% (1:50) and 2·5% (1:40). The results showed that the slope gradient does not largely affect the participants' performance of longitudinal walking on the slopes or their subjective safety evaluation, but would cause additional difficulty for them to board/alight from the train from/onto the slope. This suggests that train doors should not stop next to the ramp. There was little evidence concerning the effects of the cross-fall gradient. The results provide useful information for designing platform humps.

Experimental investigation and CFD analysis on cross flow in the core of PMR200

The Prismatic Modular Reactor (PMR) is one of the major Very High Temperature Reactor (VHTR) concepts, which consists of hexagonal prismatic fuel blocks and reflector blocks made of nuclear grade graphite. However, the shape of the graphite blocks could be easily changed by neutron damage during the reactor operation and the shape change can create gaps between the blocks inducing the bypass flow. In the VHTR core, two types of gaps, a vertical gap and a horizontal gap which are called bypass gap and cross gap, respectively, can be formed. The cross gap complicates the flow field in the reactor core by connecting the coolant channel to the bypass gap and it could lead to a loss of effective coolant flow in the fuel blocks. Thus, a cross flow experimental facility was constructed to investigate the cross flow phenomena in the core of the VHTR and a series of experiments were carried out under varying flow rates and gap sizes. The results of the experiments were compared with CFD (Computational Fluid Dynamics) analysis results in order to verify its prediction capability for the cross flow phenomena. Fairly good agreement was seen between experimental results and CFD predictions and the local characteristics of the cross flow was discussed in detail. Based on the calculation results, pressure loss coefficient across the cross gap was evaluated, which is necessary for the thermo-fluid analysis of the VHTR core using a lumped parameter code.

Sonography of subcutaneous tissue cannot determine causes of lower limb edema.

To clarify the clinical use of sonography for differentiation of edema we tried to answer the question whether a group of doctors can differentiate lymphedema from cardiac, hepatic or venous edema just by analysing sonographic images of the edema. 38 (70 ± 12 years, 22 (58 %) females) patients with lower limb edema were recruited according the clinical diagnosis: 10 (26 %) lymphedema, 16 (42 %) heart insufficiency, 6 (16 %) venous disorders, 6 (16 %) chronic hepatic disease. Edema was depicted sonographically at the most affected leg in a standardised way at distal and proximal calf. 38 sets of images were anonymised and send to 5 experienced doctors. They were asked whether they can see criteria for lymphedema: 1. anechoic gaps, 2. horizontal gaps and 3. echoic rims. Accepting an edema as lymphedema if only one doctor sees at least one of the three criteria for lymphatic edema on each single image all edema would be classified as lymphatic. Accepting lymphedema only if all doctors see at least one of the three criteria on the distal image of the same patient 80 % of the patients supposed to have lymphedema are classified as such, but also the majority of cardiac, venous and hepatic edema. Accepting lymphedema only if all doctors see all three criteria on the distal image of the same patients no edema would be classified as lymphatic. In addition we separated patients by Stemmers’ sign in those with positive and negative sign. The interpretation of the images was not different between both groups. Our analysis shows that it is not possible to differentiate lymphedema from other lower limb edema sonographically.

Marginal Assessment of Crowns by the Aid of Parallel Radiography

Introduction: Marginal adaptation is the most critical item in long-term prognosis of single crowns. This study aimed to assess the marginal quality as well asthe discrepancies in marginal integrity of some PFM single crowns of posterior teeth by employing parallel radiography in Shiraz Dental School, Shiraz, Iran. Methods: In this descriptive study, parallel radiographies were taken from 200 fabricated PFM single crowns of posterior teeth after cementation and before discharging the patient. To calculate the magnification of the images, a metallic sphere with the thickness of 4 mm was placed in the direction of the crown margin on the occlusal surface. Thereafter, the horizontal and vertical space between the crown margins, the margin of preparations and also the vertical space between the crown margin and the bone crest were measured by using digital radiological software. Results: Analysis of data by descriptive statistics revealed that 75.5% and 60% of the cases had more than the acceptable space (50µm) in the vertical (130±20µm) and horizontal (90±15µm) dimensions, respectively. Moreover, 85% of patients were found to have either horizontal or vertical gap. In 77% of cases, the margins of crowns invaded the biologic width in the mesial and 70% in distal surfaces. Conclusion: Parallel radiography can be expedient in the stage of framework try-in to yield some important information that cannot be obtained by routine clinical evaluations and may improve the treatment prognosis

Asymptotic Deployment Gain: A Simple Approach to Characterize the SINR Distribution in General Cellular Networks

In cellular network models, the base stations are usually assumed to form a lattice or a Poisson point process (PPP). In reality, however, they are deployed neither fully regularly nor completely randomly. Accordingly, in this paper, we consider the very general class of motion-invariant models and analyze the behavior of the outage probability (the probability that the signal-to-interference-plus-noise-ratio (SINR) is smaller than a threshold) as the threshold goes to zero. We show that, remarkably, the slope of the outage probability (in dB) as a function of the threshold (also in dB) is the same for essentially all motion-invariant point processes. The slope merely depends on the fading statistics. Using this result, we introduce the notion of the asymptotic deployment gain (ADG), which characterizes the horizontal gap between the success probabilities of the PPP and another point process in the high-reliability regime (where the success probability is near 1). To demonstrate the usefulness of the ADG for the characterization of the SINR distribution, we investigate the outage probabilities and the ADGs for different point processes and fading statistics by simulations.

The Mean Interference-to-Signal Ratio and Its Key Role in Cellular and Amorphous Networks

We introduce a simple yet powerful and versatile analytical framework for approximating the SIR distribution in the downlink of cellular systems. It is based on the mean interference-to-signal ratio and yields the horizontal gap (SIR gain) between the SIR distribution in question and a reference SIR distribution. As applications, we determine the SIR gain for base station silencing, cooperation, and lattice deployment over a baseline architecture that is based on a Poisson deployment of base stations and strongest-base station association. The applications demonstrate that the proposed approach unifies several recent results and provides a convenient framework for the analysis and comparison of future network architectures and transmission schemes, including amorphous networks where a user is served by multiple base stations and, consequently, (hard) cell association becomes less relevant.

Effects of mesh size and escape gaps on discarding in an Australian giant mud crab (Scylla serrata) trap fishery.

In response to concerns over excessive discarding from Australian recreational round traps (with four funnel entrances) used to target giant mud crabs, Scylla serrata, an experiment was done to assess the independent and cumulative utility of paired, bottom-located horizontal escape gaps (46×120 mm) and increasing mesh size (from 51 to 101 mm). Compared to conventional traps comprising 51-mm mesh throughout, those with the same mesh size and escape gaps caught significantly fewer (by 95%) undersize (<85 mm carapace length – CL) crabs while maintaining legal catches. Traps made from 101-mm mesh (but with the same funnel entrances as conventional designs) and with and without escape gaps similarly retained fewer undersize crabs and also yellowfin bream Acanthopagrus australis (the key bycatch species) by up to 94%, but there were concomitant reductions in fishing power for legal sizes of S. serrata. Although there were no immediate mortalities among any discarded crabs, there was a greater bias towards wounding among post molts than late inter-molts and less damage to individuals in the 101-mm conventional than 51-mm conventional traps (without escape gaps). The results support retrospectively fitting escape gaps in conventional S. serrata traps as a means for reducing discarding, but additional work is required to determine appropriate mesh sizes/configurations that maximize species and size selectivity.

Facial bone alterations on maxillary anterior single implants for immediate placement and provisionalization following tooth extraction: a superimposed cone beam computed tomography study.

The purpose of this cone beam computed tomography (CBCT) study was to describe the facial bone changes around single implants for immediate placement and provisionalization following tooth extraction in the maxillary anterior. The data between 2008 and 2013 were collected retrospectively. Superimposed facio-palatal cross-sectional CBCT images for the implants were derived from preoperative and postoperative radiographs via standardized CBCT processes. Horizontal and vertical facial measurements on the implants were identified at preoperative and approximately 1-year postoperative follow-ups. Correlation coefficient for those parameters was evaluated. A total of 12 single implants in 12 patients were included in this study. The mean loading period was 13.3months (range 12-15months). The median data of preoperative bone thickness 0.54mm (A), preoperative vertical bone level 1.46mm (B), postoperative bone thickness 1.77mm (C), postoperative vertical bone level 1.08mm (D), horizontal distance from outer surface of preoperative facial bone to implant surface 2.08mm (E), horizontal gap distance 1.41mm (E-A), horizontal bone resorption -0.26mm (E-C), and vertical bone resorption -0.25mm (B-D) were obtained. The data at the implant platform level (IPL) were selected for the horizontal measurements. Spearman's analysis demonstrated statistically significant correlations between B and D, C and E, E and E-A, and B and E-C (P<0.01). Significant correlations between C and B, D, and E-A were also found, respectively (P<0.05). Immediate placement and provisionalization of single implants procedure in the maxillary anterior showed excellent outcomes with the small facial bone alterations around the implants. Neither preoperative facial bone thickness nor horizontal gap distance influenced the amount of facial bone resorptions.

Strong light-matter interactions in sub-nanometer gaps defined by monolayer graphene: toward highly sensitive SERS substrates.

The interactions between visible light and sub-nanometer gaps were investigated by sandwiching graphene between two layers of vertically stacked Au nanoparticles. The optical properties of such a hybrid film have been effectively tuned by embedding a monolayer graphene, enabling a suppressed transmission of ∼16% accompanied by a red-shift of the resonant wavelength. Finite element simulations have shown that the strong coupling between two layers of plasmonic Au nanoparticles leads to an electric field enhancement of up to 88 times in graphene defined vertical gaps, in contrast to that of 14 times in the horizontal gaps between Au nanoparticles formed in the fabrication process. In addition, the size of gaps and thus the field enhancement can be readily tuned by the number of graphene layers sandwiched between Au nanoparticles. When being used as surface-enhanced Raman scattering (SERS) substrates, the Au nanoparticle/graphene/Au nanoparticle structures have demonstrated high Raman enhancement factors of up to 1.6 × 10(8) for RhB and 2.5 × 10(8) for R6G, and a detection limit of as low as 0.1 nM for Sudan III and methylene blue molecules.

The scaling of transport AC losses in Roebel cables with varying strand parameters

A Roebel cable is a good candidate for low-voltage windings in a high-temperature superconductor (HTS) transformer because of its high current-carrying capability and low AC loss. Transport AC loss measurements were carried out in 1.8 m long 15/5 (fifteen 5 mm wide strands) and 15/4 Roebel cables. The results were compared with those in many Roebel cables composed of 2 mm wide Roebel strands. Comparison of the AC losses hinted that the intrinsic difference in normalized transport AC losses is due to differences in the g/w (ratio of the horizontal gap between the Roebel strands over the Roebel strand width) values. The intrinsic difference was confirmed by measuring transport AC loss in a series of horizontally arranged parallel conductor pairs with various g values. A method to scale transport AC losses in Roebel cables with varying strand parameters was developed. The scaling method will be useful for a rough assessment of AC loss in one-layer solenoid winding coils, such as in a HTS transformer.

Research on narrow-gap GMAW with swing arc system in horizontal position

In this paper, a novel swing arc welding system developed for horizontal narrow gap gas metal arc welding (NG-GMAW) which was used in welding and joining heavy plate structures was designed and attempted. Using this welding system, two sound heavy plate beads, i.e., “multi-layer single-pass” welding and “multi-layer double-pass” welding structures, were obtained through adjusting swing amplitude and frequency. Two different welding structures are both without sagged molten pool and interlayer slags, especially obtaining the complete sidewall penetration. All these welding features ensure the bead with higher tensile properties and hardness than the base metal, respectively. This welding system displays considerable flexibility and convenience and possesses a tremendous advantage in the auto-welding industry.

Analysis of displacement and deformation of the medial meniscus with a horizontal tear using a three-dimensional computer model

The displacement and deformation of the knee meniscus significantly affect its roles; however, little is known about the displacement and deformation patterns of a torn medial meniscus. The objective of this study was to evaluate quantitatively the patterns of displacement and deformation in horizontally torn medial menisci during knee flexion. Twenty patients with horizontally torn medial menisci underwent three-dimensional (3-D) magnetic resonance imaging at varying degrees of knee flexion, and 3-D computer models of the tibia, tibial articular cartilage, and meniscus were generated. Based on these, the size of the horizontal tear (% tear) was evaluated and defined as the circumferential ratio between the length of the horizontal tear and that of the entire meniscus. The 3-D meniscus models were automatically superimposed over images taken at 0, 20, 40, and 60° of knee flexion by the voxel-based registration method. Meniscal motion and deformation during knee flexion were visualized and quantitatively calculated on the mid-sagittal plane. Correlations between the size of horizontal tear, displacement/deformation of torn menisci, and clinical symptoms were evaluated after conservative treatment for 3months. The % tear was 35.7±12.5% (range 13.7-55.5%). During knee flexion, all torn menisci moved posteriorly, with gradual widening of horizontal and vertical gaps (p<0.05). A direct correlation was observed between % tear and change in the vertical tear gap during knee flexion (p<0.05). There was an inverse correlation between Lysholm score and % tear (p<0.05). Medial meniscal horizontal tears widen and deform during knee flexion, and % tear correlates with the change in the vertical gap. Patients with a lower % tear are more capable of performing activities of daily living after conservative treatment. This method may help clarify the cause of pain in patients with medial meniscus tears as well as facilitate the selection of an appropriate treatment plan. Case series, Level IV.

Liquefaction and cold volcanism

The escape of pore fluid from a granular matrix has the tendency to localize into relatively thin tubes. This manifests itself in sand/water volcanos at the ground surface. In this paper this phenomenon is attributed to the following two mechanisms: (1) opening of horizontal gaps filled with pore fluid, and subsequently, (2) a sort of Rayleigh–Taylor instability exhibited due to the fact that a heavy fluid rests upon a lighter one. If the pore fluid is water, then we have the so-called cold volcanism. If the pore fluid is molten rock, then we have conventional volcanos.

Immediate Provisionalization of Implants Placed in Fresh Extraction Sockets Using a Definitive Abutment: The Chamber Concept

The purpose of this case series is to present radiographic results of implants immediately placed and restored with a definitive abutment and followed for 18 months. Ten patients who required extraction of the maxillary central or lateral incisor were treated with immediate extraction, implant placement, and provisionalization. Hard tissue measurements were performed using cone beam computed tomography. At follow-up, the mean buccal horizontal gap was -0.21 ± 0.3 mm. The mean vertical gap was 0.15 ± 0.23 mm. The mean distance between the bone crest and implant bevel was 1.73 ± 0.17 mm. The favorable results are related to a three-dimensional biologic space created around the abutment called the chamber.

An Effect of HTS Wire Configuration on Quench Recovery Time in a Resistive SFCL

We experimentally investigated the correlation between the high-temperature superconducting (HTS) wires configuration in an HTS element and recovery time after quench in a resistive superconducting fault current limiter. The variables of the configuration are horizontal and vertical gap distances between HTS tapes in an element. Eight samples were made with different gap distances and tested. A SUS-stabilized YBCO tape with 4.4 mm width had been used in the experiment. It was cooled by LN2 in a cryostat under the pressure of 1 bar, saturated state. In the short-circuit test, the temperature of the wire's surface was measured. Recovery time of the HTS sample increased with decreasing horizontal and vertical gap distance due to stagnation of bubbles. When the gap distance was larger than a size of a bubble, the effect of gap distance was ignorable. Considering a volume and recovery time, the sample that has narrower gap distance was favorable.

Escape Gaps as a Management Strategy for Reducing Bycatch in Net‐Covered Traps for the Giant Mud Crab Scylla serrata

AbstractIn response to experimental evidence and anecdotal concern about bycatch in the net‐covered traps used increasingly by recreational and commercial fishers to target giant mud crabs Scylla serrata in New South Wales, Australia, experiments were done to examine the utility of escape gaps in reducing the bycatch of Yellowfin Bream Acanthopagrus australis (also known as Surf Bream) and undersized giant mud crabs. In each of two rivers, 10 different treatments comprising four different sizes of rectangular, horizontal escape gaps (85 × 45 mm, 85 × 55 mm, 95 × 45 mm, and 95 × 55 mm) and a control (no escape gaps) applied to both two‐entrance and four‐entrance traps were tested separately during the day and night. Traps fitted with escape gaps reduced the mean numbers of Yellowfin Bream and undersized giant mud crabs by 53–78% and 58–84%, respectively. Despite some inconsistent results, the effect of escape gaps was statistically significant in four of the seven analyses. There were, however, no significant differences in the mean numbers of Yellowfin Bream and undersized giant mud crabs among the different sizes of escape gap. By contrast, the largest escape gap treatment (i.e., 95 × 55 mm) reduced the mean number of legal‐size giant mud crabs by 35–41%, which was significant in one of four analyses. Moreover, size‐selectivity analyses indicated that the largest escape gap also allowed a comparatively greater proportion of undersized mud crabs to escape. Our findings show that implementing an 85‐mm × 55‐mm escape gap could substantially reduce bycatch without affecting catches of the target organism. Further reductions in catches of undersized giant mud crabs is possible with the 95‐mm × 55‐mm treatment, but at the cost of some reduction in the catch target.Received August 19, 2011; accepted December 11, 2012

Disempowerment and marginalisation of peace NGOs: exposing peace gaps in Israel and Palestine

This article analyses the enabling and restraining conditions of local peace organisations in Israel and Palestine. It utilises the analytical notion of peace gaps to accentuate the interplay between local and elite levels. It also highlights the discrepancies when it comes to expectations of peace, the ability to communicate peace discourses and the power to influence and build wider domestic peace constituencies. The empirical findings reveal how current vertical and horizontal peace gaps result in the disempowerment and marginalisation of local peace NGOs on both sides. Such a precarious situation hinders broader peace mobilisation and is further exacerbated by widespread political apathy and peace fatigue among Israeli and Palestinian publics. By way of conclusion, the article argues for the need to re-politicise and re-negotiate space for a more agonistic peacebuilding, which allows for differences to co-exist.

On the effects of gravity and sulfur content on the weld shape in horizontal narrow gap GTAW of stainless steels

A simplified 2D axisymmetric model and a comprehensive 3D weld pool model, accounting for the free surface deformation and the filler metal addition, have been developed to investigate the factors that lead to asymmetric bead shapes in horizontal GTA welding of stainless steels. Buoyancy-induced flow and the sagging of the pool free surface, under the action of gravity, are found to be responsible for the weld asymmetry and the decrease in the weld penetration at the bottom sidewall. The numerical results clearly emphasized the beneficial role of the Marangoni shear stress in limiting the asymmetry of horizontal GTA welds. An additional experimental investigation showed that the asymmetry in the weld shape can be reduced when placing the lowest sulfur content component at the bottom side.