Laboratory and numerical investigation on strength performance of inclined pillars

Pillars play a critical role in an underground mine, as an inadequate pillar design could lead to pillar failure, which may result in catastrophic damage, while an over-designed pillar would lead to ore loss, causing economic loss. Pillar design is dictated by the inclination of the ore body. Depending on the orientation of the pillars, loading can be axial (compression) in horizontal pillars and oblique (compression as well as shear loading) in inclined pillars. Empirical and numerical approaches are the two most commonly used methods for pillar design. Current empirical approaches are mostly based on horizontal pillars, and the inclination of the pillars in the dataset is not taken into consideration. Laboratory and numerical studies were conducted with different width-to-height ratios and at different inclinations to understand the reduction in strength due to inclined loading and to observe the failure mechanisms. The specimens’ strength reduced consistently over all the width-to-height ratios at a given inclination. The strength reduction factors for gypsum were found to be 0.78 and 0.56, and for sandstone were 0.71 and 0.43 at 10? and 20? inclinations, respectively. The strength reduction factors from numerical models were found to be 0.94 for 10? inclination, 0.87 for 20? inclination, 0.78 for 30? inclination, and 0.67 for 40? inclination, and a fitting equation was proposed for the strength reduction factor with respect to inclination. The achieved results could be used at preliminary design stages and can be verified during real mining practice

An Effiecient Approach for Resource Auto-Scaling in Cloud Environments

Cloud services have become more popular among users these days. Automatic resource provisioning for cloud services is one of the important challenges in cloud environments. In the cloud computing environment, resource providers shall offer required resources to users automatically without any limitations. It means whenever a user needs more resources, the required resources should be dedicated to the users without any problems. On the other hand, if resources are more than user’s needs extra resources should be turn off temporarily and turn back on whenever they needed. In this paper, we propose an automatic resource provisioning approach based on reinforcement learning for auto-scaling resources according to Markov Decision Process (MDP). Simulation Results show that the rate of Service Level Agreement (SLA) violation and stability that the proposed approach better performance compared to the similar approaches

Effect of homogeneous ceramic tile waste on properties of mortar

The subject of reduce, reuse and recycle of waste material either from industrial or agricultural sectors is considered very important in the general attempt for sustainable construction. In relation to that, ceramic materials are widely used in many part of the world and consequently, large quantities of wastes are produced simultaneously by brick and tile manufacturers and construction industry. However, part of these wastes and those produced by the construction industry are dumped in landfills. In this present research, the effect of homogeneous ceramic tile waste on harden properties of mortar was investigated. Mortar mixes were prepared focusing on the effect of ceramic aggregates as river sand replacement. Tests were conducted for compressive strength, splitting tensile strength for all mortar specimens. The cement was partially replaced by ceramic powder by 20 %, 40 % and 60 %, respectively by weight of cement. The sand was replaced by ceramic aggregates ranging from 0% to 100% by weight of aggregates. The size of ceramic aggregates used is modified in accordance with ASTM C-33 while the cement was partially replaced by 40 % of ceramic powder by weight of cement. All specimens were cast in 50 mm cubes and cured in water after demoulding until the age of testing. By replacing 100 % of sand with ceramic aggregates, it was found that the compressive strength was very much similar to the control specimen without showing any negative effect. Similarly, by replacing cement with ceramic powder, the strength of mortar shows 10% increment as compared to control specimen. In conclusion, incorporation of homogenous ceramic tile waste either as sand replacement or cement replacement both can enhance the properties of mortar in fresh and hardened states

Polysubstance-induced relapse of schizoaffective disorder refractory to high-dose antipsychotic medications: a case report

BACKGROUND: The high prevalence of comorbid illicit drug use in persons with chronic psychotic illness represents a strong determinant of psychotic relapse and rehospitalization. Epidemiological studies indicate changing patterns of illicit drug use in Australia, which are concerning because of increased use of crystal methamphetamine, also known as "ice." An important complication of habitual use of crystal methamphetamine is the development of a dose-dependent acute psychotic reaction. We report a case of an acute psychotic relapse in response to polydrug use most notable for multiple recent binges of crystal methamphetamine. Unlike previously described case reports, our patient\u27s acute psychosis was refractory to ultra-high doses of multiple antipsychotic medications. This presented safety challenges due to the risk of serious side effects with high-dose antipsychotic medications.CASE PRESENTATION: A 30-year-old white man with a past history of schizoaffective disorder was brought to our emergency department by the police in a state of extreme agitation, combativeness, and paranoia after use of cannabis and crystal methamphetamine. Despite existing compliance with zuclopenthixol decanoate depot medication, he required multiple emergency injections of zuclopenthixol acetate, and regular high-dose droperidol, chlorpromazine, and lorazepam. However, he remained severely agitated and psychotic with continuous threats of harm to others. A test of antipsychotic drug metabolism by cytochrome P450 enzymes did not reveal a pharmacogenetic cause for the poor therapeutic efficacy of antipsychotic medications. His psychosis did not appear to be modified by psychoactive medications but was instead self-limited to the presence of endogenous methamphetamine within his system. He fully recovered 96 to 120 hours post-presentation and was discharged home with out-patient clinic follow-up.CONCLUSIONS: The current case highlights the challenging nature of a severe psychotic relapse precipitated by illicit substances that is resistant to medical management. High doses of multiple antipsychotic medications may be required to manage dangerous behaviors associated with these acute psychotic relapses. These patients require close monitoring for adverse effects with adjustment of dosing to ensure the optimal balance of risk versus benefit while the patient is acutely psychotic. The results are of relevance for the management of psychiatric emergencies in emergency departments and acute mental health settings

Long term studies on compressive strength of high volume ultrafine palm oil fuel ash mortar mixes

The long term characteristics of nano palm oil fuel ash in the mortar were investigated. This study covers basic properties like the morphology, porosity, compressive strength and microstructure properties with regards to the variations in the mix design process of mortar. To get a better performance in terms of strength development, the ash used has gone through heat treatment and was ground up to nano size. The mortar mixes were cast in 70x70x70mm cubes for compressive strength test. The incorporation of more than 80% nano size palm oil fuel ash as cement replacement has produced a mortar having a compressive strength more than OPC mortar at a later age. By treating the palm oil fuel ash to nano size, help reduce the cost of expensive admixture for improving the compressive strength of mortar. The results also revealed that the compressive strength of mortar using nano size palm oil fuel ash shows higher value as compared to initial strength at the later age of 1 year by 25%. The porosity of 80% nano palm oil fuel ash mortar reduced 51% as the age of curing increased. The overall results have revealed that the inclusion of high volume nano palm oil fuel ash can produce a mortar mix with high strength, low porosity, good quality and most importantly that is more sustainable

Effects of steel fibres on concrete properties and flexural behaviour of reinforced concrete slabs

Concrete is a material that is good in compression but weak in tension. Enhancing the tensile properties of concrete will lead to its greater application in construction. It was reported that improvement on the mechanical properties of reinforced concrete structure can be achieved by the inclusion of short fibres. The use of short steel fibres have been reported to increase the toughness, abrasion, impact resistances and allow for decrease in concrete slab thickness. This paper focuses on the study conducted in the laboratory on the effect of steel fibre on concrete properties and behaviour of steel fibre reinforced concrete slabs under flexure with different amount of tensile reinforcements. A number of concrete cubes and prisms with and without steel fibres, 0%, 0.5%, 1.0%, 1.5% and 2.0% together with four reinforced concrete slabs having different amount of tensile reinforcement were cast and tested to failure in flexure. The optimum dosage of steel fibre to be included in concrete slab was 1%. The reinforced concrete slabs manufactured consist of slab with tensile reinforcement bar of R-150 as control slab, slab with tensile reinforcement bar of R-300 and 1% dosage of steel fibres, slab with 1% dosage of steel fibres without tensile reinforcement, and one plain concrete slab without reinforcement. All the slabs cast having the overall dimensions of 100 x 500 x 1000 mm, and tested to failure under four point loading. Cube compressive strength, modified compressive strength, flexural strength, ultrasonic pulse velocity test and rebound hammer test were conducted. The behaviour of the reinforced concrete slabs was studied through their ultimate load, load-deflection characteristic upon loading, cracking history, and mode of failure. The experimental results show that the inclusion of steel fibres was found to improve the compressive strength, slightly lowered the UPV value but no significant effect on the rebound hammer compared to the control sample. It was also found that based on slab SB-R300-1SF the inclusion of steel fibres increased the ultimate load of the slab by 25%, reduce the tensile reinforcement by about 50%, improve the flexural stiffness and ductility of the slab when compared to the control slab, SC-R150

Mechanical properties and self-healing mechanism of epoxy mortar

Crack deformation in concrete start with hairline crack or micro-crack which can lead to major crack if not prevented. Crack can cause a major deterioration to the structure as liquid can penetrate inside and cause damage as a result; the durability of concrete will decrease. Self-healing concrete was introduced to automatically repair hairline crack or micro-crack without external intervention. Previous study had shown that by introducing bacteria into the concrete, the crack will heal itself. This paper presents the study on self-healing mortar by using epoxy resin without hardener as a self-healing agent. The self-healing process was evaluated using Ultrasonic Pulse Velocity measurements up to 180 days. Mortar specimens were prepared with mass ratio of 1:3 (cement: fine aggregate), water-cement ratio of 0.48 and 10% epoxy resin of cement content. All tested specimens were subjected to wet-dry curing; where compressive strength, flexural strength, and tensile splitting strength and self-healing mechanism were measured. The results obtained shows that, all strength properties of the self-healing epoxy mortar were significantly higher than the control sample and became constant at 10 % of epoxy resin content. Based on the pulse velocity measurements, after 60 days the cracks of the mortar healed automatically as a result of the reaction between the unhardened epoxy resin and hydroxyl ion from cemen

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London