scholarly journals Innovative Control Technique for the Floor Heave in Goaf-Side Entry Retaining Based on Pressure Relief by Roof Cutting

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Guangyuan Yu ◽  
Jiong Wang ◽  
Jinzhu Hu ◽  
Daoyong Zhu ◽  
Han Sun ◽  
...  
Keyword(s):  
Field Testing ◽  
Mechanical Analysis ◽  
New Technique ◽  
Control Technique ◽  
Pressure Relief ◽  
Floor Heave ◽  
Before And After ◽  
Direction Control ◽  
Coal Wall ◽  
Overlying Strata

To solve the difficulty in controlling floor heave of a retained goaf-side roadway, a new control technique was investigated from the perspective of the pressure relief by roof cutting by combining mechanical analysis, numerical simulation, and engineering tests. The mechanical principle of controlling the floor heave based on pressure relief by roof cutting was attained by analyzing the movement of overlying strata and mechanical characteristics of key blocks before and after the roof cutting. A new technique for controlling the floor heave based on pressure relief by roof cutting was proposed. Research results have shown that after performing pressure relief by roof cutting, the caved gangues in the goaf can support the overlying strata and, thereby, change the movement law thereof and weaken the abutment pressure on the coal wall. Furthermore, the pressure exerted on the roadway floor by the coal wall is lowered to prevent plastic deformation of the floor, thus controlling floor heave in the roadway; a new integrated technique for controlling the floor heave based on pressure relief by roof cutting, flexible yielding, controlling with double-direction-control anchor bolts, and controlling with reinforcing anchor cables is developed, and the technological processes of support, cutting, and protection are summarised. The results of field testing showed that, after applying the new technique, the average floor heave amount of the roadway declines by 64% and the average speed of the floor heave up to 231 m behind the working face decreases by 61%.

scholarly journals Comparison of Latanoprost/Timolol with Carbonic Anhydrase Inhibitor and Dorzolamide/Timolol with Prostaglandin Analog in the Treatment of Glaucoma

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Kenji Inoue ◽  
Shoichi Soeda ◽  
Goji Tomita
Keyword(s):  
Visual Field ◽  
Fixed Combination ◽  
Open Angle Glaucoma ◽  
Field Testing ◽  
Mean Deviation ◽  
Single Action ◽  
Before And After ◽  
Group 2 ◽  
Concomitant Medications ◽  
Medication Changes

Purpose.We retrospectively reviewed medical records of glaucoma patients to investigate how switching medications may affect intraocular pressure (IOP) management. Three concomitant medications were changed to two medications: one combination drop and one single-action drop. Associated adverse effects were also examined.Subjects and Methods.A total of 112 patients with primary open-angle glaucoma or ocular hypertension were examined. All patients were concomitantly using a prostaglandin (PG) analog, aβ-blocker, and a carbonic anhydrate inhibitor (CAI). Fifty-five patients began using latanoprost (PG analog)/timolol (β-blocker) fixed-combination (LTFC) drops and a CAI (group 1), and 57 patients began using dorzolamide (CAI)/timolol fixed-combination (DTFC) drops and a PG analog (group 2). The IOP was measured every 6 months for 2 years following medication changes. Changes in visual field mean deviation (MD) and medication discontinuations were also examined.Results.There were no significant differences in IOP or MD values before and after medication changes in either group. The proportion of medication discontinuations, uncontrolled IOP, and adverse reactions was similar in both groups.Conclusion.Switching patients from multiple single-action medications to combination medications was not associated with changes in IOP, visual field testing results, or adverse event frequency.

Non-vascularized toe phalanx transfer for correction of severe clinodactyly of the thumb in Rubinstein–Taybi syndrome

2020 ◽  
Vol 45 (7) ◽  
pp. 715-721
Author(s):  
Marie Le Mapihan ◽  
Alina Badina ◽  
Stéphanie Pannier ◽  
Arielle Salon ◽  
Chrisophe Glorion ◽  
...  
Keyword(s):  
New Method ◽  
New Technique ◽  
Level Of Evidence ◽  
Before And After ◽  
Long Term Follow Up ◽  
Osteotomy Technique ◽  
Toe Transfer ◽  
Delta Phalanx

In Rubinstein–Taybi syndrome, patients may have a particularly severe clinodactyly of the thumb. We evaluated a new method for correction of these severe clinodactylies using non-vascularized toe phalanx transfer as a replacement for the abnormal delta phalanx. Results of the new technique are presented, together with those of an osteotomy technique. We retrospectively recorded the angle of the clinodactyly before and after surgery and at long-term follow-up of 11 osteotomies and five transfers in nine patients from 1990 to 2017. The pre-operative angle of clinodactyli was similar between the two groups with a mean of 59°. After surgery, the correction was equivalent (7° and 11°). At the last follow-up (7 and 18 years), the relapse of clinodactyly was 17° for osteotomies and 1° for phalanx transfers. We noticed growth of the transferred phalanx, resulting in an excellent thumb length. We conclude that non-vascularized toe transfer can be an effective correction of severe clinodactyly and may be more stable than osteotomy in the long-term. Level of evidence: IV

scholarly journals The Key Stratum Structure Morphology of Longwall Mechanized Top Coal Caving Mining in Extra-Thick Coal Seams: A Typical Case Study

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Fulian He ◽  
Xiaobin Li ◽  
Wenrui He ◽  
Yongqiang Zhao ◽  
Zhuhe Xu ◽  
...  
Keyword(s):  
Coal Seam ◽  
Cantilever Beam ◽  
Coal Seams ◽  
Key Strata ◽  
Key Stratum ◽  
Structure Morphology ◽  
Coal Wall ◽  
Coal Seam Thickness ◽  
Longitudinal Cracks ◽  
Overlying Strata

Longwall mechanized top coal caving mining (LMTCCM) in extra-thick coal seams has its own characteristics. The law of mining pressure and overlying strata failure height in extra-thick coal seams are much larger than those of medium-thick and thick coal seams. The key stratum structure morphology also has an important influence on the law of overlying strata movement and stability of surrounding rock. Based on the engineering geological conditions, this paper used the method of theoretical analysis and numerical simulation to study the key stratum structure morphology of LMTCCM in extra-thick coal seams. The results show that under the condition of LMTCCM in extra-thick coal seams, the key stratum forms the structure of low cantilever beam and high hinged rock beam. With the increase of coal seam thickness, the breaking position of cantilever beam is closer to the coal wall. Through theoretical calculation, it is obtained that the breaking length of cantilever beam is 31.5 m and the breaking position of cantilever beam is 15.4 m away from coal wall. With the increase of cycle, key strata will undergo the evolution law from the generation of longitudinal cracks to the hinged structure and then to the cantilever beam structure. The breakage of key strata will cause the expansion of longitudinal cracks and the overall synchronous movement of overlying strata. With the increase of coal seam thickness, the distribution of longitudinal cracks will gradually transfer from the upper part of goaf to the deep part of coal body in space and increase in quantity. This research is of great significance for improving the stability of overlying strata and ensuring the safe and efficient mining of extra-thick coal seams.

Optimization Study of Advance Support in the Roadway of Paste Filling Working Face

2011 ◽  
Vol 255-260 ◽  
pp. 3702-3707
Author(s):  
Shao Jie Chen ◽  
Wei Jia Guo ◽  
Hai Long Wang ◽  
Bo Li
Keyword(s):  
Working Face ◽  
Optimization Study ◽  
Coal Wall ◽  
The Face ◽  
Strata Behavior ◽  
Behavior Characteristics ◽  
Working Efficiency ◽  
Practical Measure ◽  
Main Influence ◽  
Overlying Strata

On the basis of the field measurement, the characteristics of advance strata behavior are analyzed in the past filling working face and the advance support method is optimized in the roadway. The practical measure researches show that, because the paste filling supports the overlying strata of the goaf availably, the strata behaviors of 2351 paste filling working face in Daizhuang coalmine are not obvious; And the protective pillar bears a little load, The strata behaviors in non-production side are smaller than that in production side. The overlying strata gravity mainly acts on the coal wall in front of the face and the paste filling in the goaf. The value and main influence range of advance stress in front of the face is quite small and the main influence range is less than 15m. According to the advance strata behavior characteristics of the paste filling working face, the advance support of the track roadway is changed from 3 rows to 2 rows. And the support length of each row reduces from 20m to 15m. The advance support after optimizing can reduce the labor intensity greatly and improve the working efficiency of backfill mining.

Simulation of Steam Explosion with a General Purpose CFD Code

2006 ◽  
Author(s):  
Matjazˇ Leskovar ◽  
Bosˇtjan Koncˇar
Keyword(s):  
Heat Transfer ◽  
Steam Explosion ◽  
Volume Fraction ◽  
Mechanical Analysis ◽  
General Purpose ◽  
Reactor Accident ◽  
Pressure Relief ◽  
Pressurized Water ◽  
Explosion Pressure ◽  
Flow Conservation

An ex-vessel steam explosion may occur when during a severe reactor accident the reactor vessel fails and the molten core pours into the water in the reactor cavity. A steam explosion is a fuel coolant interaction process where the heat transfer from the melt to water is so intense and rapid that the timescale for heat transfer is shorter than the timescale for pressure relief. This can lead to the formation of shock waves and production of missiles at later times, during the expansion of the highly pressurized water vapor, that may endanger surrounding structures. In contrast to specialized steam explosion CFD codes, where the steam explosion is modeled on micro-scale using fundamental averaged multiphase flow conservation equations, in the presented approach the steam explosion is modeled in a simplified manner as an expanding high-pressure premixture of dispersed molten fuel, liquid water and vapor. Applying the developed steam explosion model, a comprehensive analysis of the ex-vessel steam explosion in a typical PWR reactor cavity was done using the CFD code CFX-10. At four selected locations, which are of importance for the assessment of the vulnerability of cavity structures, the pressure histories were recorded and the corresponding pressure impulses calculated. The pressure impulses determine the destructive potential of the steam explosion and represent the input for the structural mechanical analysis of the cavity structures. The simulation results show that the pressure impulses depend mainly on the steam explosion energy conversion ratio, whereas the influence of the premixture vapor volume fraction, which is a parameter in our model and determines the maximum steam explosion pressure, is not significant.

The Relationship of Lactate to 1-Mile Walk Performance in Women Aged 60 to 70 Years

1998 ◽  
Vol 6 (3) ◽  
pp. 285-289 ◽  
Author(s):  
Carmelo Bazzano ◽  
Lee N. Cunningham ◽  
Giovanni Cama ◽  
Tony Falconio
Keyword(s):  
Older Women ◽  
Blood Lactate ◽  
Field Testing ◽  
Testing Procedure ◽  
Physiological Data ◽  
Walk Test ◽  
Treadmill Test ◽  
Physiological Variables ◽  
Before And After ◽  
The Relationship

The purpose of this study was to examine the relationship between selected physiological variables and lactate accumulation at the end of a l-mile walk test (MWT) in older women (mean ± SD: 64.6 ± 3.1 years). Seventeen women with a peak (ml · kg-1 · min-1) of 21.1 ± 4.2 volunteered to participate. Physiological data were obtained via a COSMED K2 miniaturized O2 analyzer with telemetric capabilities during a maximal treadmill (TM) test and MWT. Blood samples were obtained from the ear lobe for lactale analysis immediately before and after the treadmill test and MWT. Subjects performed the MWT in 15.4 ± 1.4 min at an intensity of 76% of peak and 86% of HRmax. The blood lactate accumulated at the end of the MWT was 2.61 ± 1.47 mmol/L. Peak lactate following the maximal treadmill test was 3.8 ± 1.42 mmol/L. HR during the test was significantly related with blood lactate (r= .65, p< .01). The lactate values observed during the lest suggest that the I-mile walk test is a suitable field testing procedure for older women.

Effects of open field testing and associated handling v. handling alone on the adrenocortical reactivity of piglets around weaning

2002 ◽  
Vol 74 (3) ◽  
pp. 485-491 ◽  
Author(s):  
M. S. Herskin ◽  
K. H. Jensen
Keyword(s):  
Blood Sample ◽  
Open Field ◽  
Field Testing ◽  
Blood Sampling ◽  
Cortisol Response ◽  
Temporal Development ◽  
Novel Object ◽  
Before And After ◽  
Pre Treatment

AbstractEffects of open field testing and associated handling (including blood sampling) v. handling (with blood sampling) alone on adrenocortical reactivity were investigated in piglets around weaning. After weaning at day 28, piglets were mixed to form eight replicates with three litter each and kept on slatted floors. Treatments were open field/novel object testing and associated handling (OFT + H) v. handling alone (H) (no. = 40). Testing took place on the following days (weaning day 0): -4, 0, 1, 4 and 8 (no. = 16). The open field/novel object test lasted 10 min and blood was sampled by venipuncture before and after the test and/or handling procedures. In the first blood sample, plasma concentration of cortisol did not differ between OFT + H and H piglets. In the second blood sample, however, OFT + H piglets had a higher concentration of cortisol and a larger increase in cortisol than H piglets (P < 0·01). In the first blood sample the concentration of cortisol was affected by day (P < 0·05), with concentration on day -4 being lower than those on day 0, 1, and 4 and the concentration on day 8 was lower than the concentration on day 0 as well. However, no differences were found between days for the second blood sample nor the adrenocortical reactivity. In conclusion, the increase in pre-treatment cortisol in the first 4 days after weaning as well as the lack of changes in the adrenocortical reactivity after weaning suggest that the temporal development of HPA activity and reactivity in piglets after weaning are comparable with other, more standardized long-term stressors. Exposure to an open field/novel object test and associated handling results in higher adrenocortical reactivity than handling alone but the latter (including blood sampling) in itself accounts for proportionately 0·74 of the cortisol response.

Barrier and biodegradable properties of corn starch-derived biopolymer film filled with nanoclay fillers

2016 ◽  
Vol 33 (3) ◽  
pp. 309-336 ◽  
Author(s):  
TP Mohan ◽  
Kay Devchand ◽  
K Kanny
Keyword(s):  
Water Absorption ◽  
Corn Starch ◽  
Barrier Properties ◽  
Mechanical Analysis ◽  
Oxygen Permeation ◽  
Transmission Electron Microscopy Analysis ◽  
Transmission Electron ◽  
Before And After ◽  
Electron Microscopy Analysis ◽  
Nanoclay Content

The objective of this work is to study the effect of nanoclay fillers on the biodegradation and barrier properties of corn starch polymer-based biofilm. Starch derived from corn plant source was used to prepare a biofilm by plasticization method. The barrier properties, namely, water absorption, moisture permeation, oxygen permeation and swelling of unfilled and nanoclay-filled corn starch biofilms were examined. The results indicate: ∼22% reduced water absorption, 40% reduced moisture uptake, 30% reduced oxygen permeation and 31% reduced swelling for 2–3 wt.% nanoclay-filled biofilm, when compared with unfilled biopolymer. The biodegradation result of unfilled and nanoclay-filled film series indicates that the nanoclay addition delays the biodegradation and is a function of nanoclay content in the film. The tensile, dynamic mechanical analysis and biodegradable studies were conducted on the biopolymers before and after water absorption, and the result shows that the nanoclay-filled biopolymer increased these properties when compared with unfilled biopolymer even after water absorption and is dependent on the nanocomposite structure and morphology as examined by X-ray diffraction and transmission electron microscopy analysis.

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