98 research outputs found

    Phenomena of stability of the coal seam roof with a yielding support

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    Purpose. Determining the conditions and parameters for ensuring the stability of the coal seam roof with a yielding support in the area adjacent to face and behind it under the influence of dynamic loads based on the analytical and laboratory studies. Methods. To achieve the purpose set, analytical studies have been carried out using the basic principles of the theory of elasticity and vibrations, the hypothesis of girders and the hinged-block displacement of the stratified rock stratum. Also, the laboratory studies of models from equivalent materials have been performed, in which the coal seam roof is presented in the form of a girder having a yielding support with variable rigidity from the filling material under dynamic load. Findings. As a result of performed studies, the phenomenon has been determined that the condition for the stability of the coal seam roof is a geometric parameter that reflects moving of the girder with a yielding support, under the force impact of a falling load with a known mass and the physical-geometrical characteristics of the deformable system. It has been determined that as a result of a change in the spans length, a change in the flexural rigidity of the girder occurs, which means that the yield influence of the same supports on the stability of the coal seam roof is different. The values have been set and the relationship has been studied of the physical-mechanical characteristics of the filling mass as a yielding support. Originality. It has been proven scientifically that the stress-strain state (SSS) of a system in which the coal seam roof is studied as a girder depends on the physical-geometrical characteristics of the system, as well as the type and place of applying the external load, in case when the law of the girder movement in time is determined. Practical implications. The effective supporting of the undermined rock stratum in the working part of the longwall face and behind the face is achieved by placing the yielding supports in the mined-out space or by using the backfill in the mined-out space while conducting the stope operations, thus, increasing the efficiency of measures to protect the labour of miners in coal mines.Мета. Визначення умов і параметрів забезпечення стійкості покрівлі пласта з податливою опорою у привибійному просторі та позаду очисного вибою під впливом динамічних навантажень на основі аналітичних і лабораторних досліджень. Методика. Для досягнення поставленої мети були виконані аналітичні дослідження із застосуванням основних положень теорії пружності й коливань, гіпотези балок і шарнірно-блокового зсування породної товщі, що розшаровується, а так само лабораторні дослідження моделей з еквівалентних матеріалів, в яких покрівля вугільного пласта представлена у вигляді балки, що має податливу опору змінної жорсткості із закладного матеріалу при динамічному навантаженні. Результати. В результаті виконаних досліджень визначено феномен, що умовою стійкості покрівлі вугільного пласта, є геометричний параметр, що відображає переміщення балки з піддатливою опорою, при силовому впливі падаючого вантажу відомої маси і фізико-геометричні характеристики деформованої системи. Визначено, що в результаті зміни довжини прольотів, відбувається зміна згинальної жорсткості балки, а значить вплив податливості одних і тих же опор, на стійкість покрівлі вугільного пласта різний. Встановлено величини і досліджено взаємозв’язок фізико-механічних характеристик закладного масиву як піддатливої опори. Наукова новизна. Науково доведено, що напружено-деформований стан системи, в якій покрівля вугільного пласта досліджується як балка, залежить від фізико-геометричних характеристик системи, виду і місця докладання зовнішнього навантаження, коли визначено закон руху балки в часі. Практична значимість. Ефективне підтримання підробленої породної товщі в робочій частині лави і позаду очисного забою, досягається за рахунок розміщення у виробленому просторі піддатливих опор або застосування закладки виробленого простору при веденні очисних робіт, що так само підвищує ефективність заходів з охорони праці гірників у вугільних шахтах.Цель. Определение условий и параметров обеспечения устойчивости кровли пласта с податливой опорой в призабойном пространстве и позади очистного забоя под воздействием динамических нагрузок на основе аналитических и лабораторных исследований. Методика. Для достижения поставленной цели были выполнены аналитические исследования с применением основных положений теории упругости и колебаний, гипотезы балок и шарнирно-блокового сдвижения расслоившейся породной толщи, а также лабораторные исследования моделей из эквивалентных материалов, в которых кровля угольного пласта представлена в виде балки, имеющей податливую опору переменной жесткости из закладочного материала при динамической нагрузке. Результаты. В результате выполненных исследований определен феномен, что условием устойчивости кровли угольного пласта является геометрический параметр, отражающий перемещение балки с податливой опорой, при силовом воздействии падающего груза известной массы и физико-геометрические характеристики деформируемой системы. Определено, что в результате изменения длины пролетов, происходит изменение изгибной жесткости балки, а значит влияние податливости одних и тех же опор, на устойчивость кровли угольного пласта различно. Установлены величины и исследована взаимосвязь физико-механических характеристик закладочного массива как податливой опоры. Научная новизна. Научно доказано, что напряженно-деформированное состояние системы, в которой кровля угольного пласта исследуется как балка, зависит от физико- геометрических характеристик системы, вида и места приложения внешней нагрузки, когда определен закон движения балки во времени. Практическая значимость. Эффективное поддержание подработанной породной толщи в рабочей части лавы и позади очистного забоя, достигается за счет размещения в выработанном пространстве податливых опор или применения закладки выработанного пространства при ведении очистных работ, что так же повышает эффективность мероприятий по охране труда горнорабочих в угольных шахтах.The authors express their gratitude to the staff of the Mining Department of Donetsk National Technical University and Krasnoarmiisk (Pokrovsk) Industrial Institute for assistance in conducting the laboratory research

    Design and Implementation of an Auto result Computation System

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    Different approaches to meeting with targets in the area of computing and compiling results where looked at, the most used approach is the use of spreadsheet where users will develop custom functions and formulas to actualize their targets. The essence of this work is to design a generic system that can be adopted by any institution of higher learning to making the computation of results a lot more easier and as it is also more of error free and presents more accurate results as the title suggested; “AUTORESULT COMPUTATIONSYSTEM”. An extensive research was carried out to study and ascertain the mode of computation across various institutions thereby presenting a system that can be adopted across the globe. Whilst the work is to be used by a professor or a lecturer singly, my plan is to do more research to have a central system where all results from all professors can be submitted and be computed accordingly

    Design of a HACCP plan for indigenous chicken slaughter house in Kenya

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    Indigenous chicken rearing is seen as a poverty alleviation and food security strategy especially in rural households in Africa. Chicken meat is a delicacy in almost every household in Kenya. It is a common food in restaurants and hotels that serve fast foods in urban areas. Demand for and consumption of indigenous chicken meat in Kenya has been on the rise. Many slaughterhouses have been set up in strategic locations close to towns or in towns to allow for quick supply of the dressed chicken carcass to consumers. Poultry meat is a low acid food and has been associated with the presence of foodborne pathogens such as Campylobacter, Escherichia coli, Salmonella enteritidis, and Staphylococcus aureus, especially when processing conditions are not hygienic. Hazard Analysis and Critical Control Point (HACCP) is based on a scientific verifiable process to identify, control, reduce or eliminate any potential hazards to guarantee food safety. The current study was conducted based on the actual production conditions of the slaughter house. It was initiated through a survey that looked into the operations of the slaughter house on the basis of good manufacturing practices, as well as standard operation and sanitation procedures. From the results of the study and the gap audit analysis based on a checklist, the HACCP study was commissioned. The study aimed at developing a HACCP system; based on the seven HACCP principles and a critical scrutiny of several existing models. Four Critical Control Points (CCPs) were identified and a HACCP plan, complete with perquisite programs was presented to deal with the identified hazards and, therefore, present the consumers with high quality and safe products. Design of a model for the application and operationalization of HACCP system was undertaken as an important step in ensuring consumers enjoy safe products from the indigenous chicken meat prepared from the slaughter house.Key words: Indigenous chicken, slaughter house, HACCP, Critical control points (CCPs

    Modifikasi Sistem Plc S5 Ke S7 Pada Konveyor Jalur 1 Hotcell Irm

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    MODIFIKASI SISTEM PLC S5 KE S7 PADA KONVEYOR JALUR 1 HOTCELL IRM. Telah dilakukan modifikasi sistem program PLC (Programmable Logic Controller) dari Simatic5 (S5) ke Simatic7 (S7), Siemens, pada konveyor jalur-1 dari hotcell Instalasi Radiometalurgi (IRM), yang menghubungkan hotcell diantara hotcell uji 07 dan konveyor glove box di operating area. Modifikasi ini dilakukan karena teknologi PLC S5 dalam keadaan rusak dan perlu penggantian serta ditingkatkan kemampuannya dengan menggunakan PLC S7. Tujuannya adalah merevitalisasi kembali PLC konveyor yang rusak tersebut dengan program terbaru sehingga lebih andal dan mudah dalam troubleshooting serta perawatannya. Modifikasi sistem dilakukan dengan mengganti peralatan utama CPU S5 dengan CPU S7, dan memperbaharui program dengan menggunakan ladder pada perangkat lunak S755 Siemens yang masih menggunakan proximity switch sebagai sensor posisi disetiap posisinya (hotcell). Hasil dari modifikasi ini menunjukkan bahwa alat tersebut dapat beroperasi kembali dengan baik. Indikasi utama dari unjuk kerjanya yaitu, konveyor dapat dioperasikan secara manual dan otomatis dengan ketepatan posisi box konveyor disetiap stasiunnya (hotcell)

    inv(X)(p11.4p11.22) BCOR/CCNB3 in bone sarcoma

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    Review on inv(X)(p11.4p11.22) BCOR/CCNB3 in bone sarcoma, with data on clinics, and the genes involved

    High frequency of variants of candidate genes in black Africans with low renin-resistant hypertension

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    OBJECTIVES Black subjects tend to retain salt and water, be more sensitive to aldosterone, and have suppression of plasma renin activity. Variants of the renal sodium channel (ENaC, SCNN1B) account for approximately 6% of resistant hypertension (RHT) in Blacks; other candidate genes may be important. METHODS Six candidate genes associated with low renin-resistant hypertension were sequenced in Black Africans from clinics in Kenya and South Africa. CYP11B2 was sequenced if the aldosterone level was high (primary aldosteronism phenotype); SCNN1B, NEDD4L, GRK4, UMOD, and NPPA genes were sequenced if the aldosterone level was low (Liddle phenotype). RESULTS There were 14 nonsynonymous variants (NSVs) of CYP11B2: 3 previously described and associated with alterations in aldosterone synthase production (R87G, V386A, and G435S). Out of 14, 9 variants were found in all 9 patients sequenced. There were 4 NSV of GRK4 (R65L, A116T, A142V, V486A): At least one was found in all 9 patients; 3 were previously described and associated with hypertension. There were 3 NSV of SCNN1B (R206Q, G442V, and R563Q); 2 previously described and 1 associated with hypertension. NPPA was found to have 1 NSV (V32M), not previously described and NEDD4L did not have any variants. UMOD had 3 NSV: D25G, L180V, and T585I. CONCLUSIONS A phenotypic approach to investigating the genetic architecture of RHT uncovered a surprisingly high yield of variants in candidate genes. These preliminary findings suggest that this novel approach may assist in understanding the genetic architecture of RHT in Blacks and explain their two fold risk of stroke

    ORCHIDEE-PEAT (revision 4596), a model for northern peatland CO2, water, and energy fluxes on daily to annual scales

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    Peatlands store substantial amounts of carbon and are vulnerable to climate change. We present a modified version of the Organising Carbon and Hydrology In Dynamic Ecosystems (ORCHIDEE) land surface model for simulating the hydrology, surface energy, and CO2 fluxes of peatlands on daily to annual timescales. The model includes a separate soil tile in each 0.5 degrees grid cell, defined from a global peatland map and identified with peat-specific soil hydraulic properties. Runoff from non-peat vegetation within a grid cell containing a fraction of peat is routed to this peat soil tile, which maintains shallow water tables. The water table position separates oxic from anoxic decomposition. The model was evaluated against eddy-covariance (EC) observations from 30 northern peatland sites, with the maximum rate of carboxylation (V-cmax) being optimized at each site. Regarding short-term day-to-day variations, the model performance was good for gross primary production (GPP) (r(2) = 0.76; Nash-Sutcliffe modeling efficiency, MEF = 0.76) and ecosystem respiration (ER, r(2) = 0.78, MEF = 0.75), with lesser accuracy for latent heat fluxes (LE, r(2) = 0.42, MEF = 0.14) and and net ecosystem CO2 exchange (NEE, r(2) = 0.38, MEF = 0.26). Seasonal variations in GPP, ER, NEE, and energy fluxes on monthly scales showed moderate to high r(2) values (0.57-0.86). For spatial across-site gradients of annual mean GPP, ER, NEE, and LE, r(2) values of 0.93, 0.89, 0.27, and 0.71 were achieved, respectively. Water table (WT) variation was not well predicted (r(2) <0.1), likely due to the uncertain water input to the peat from surrounding areas. However, the poor performance of WT simulation did not greatly affect predictions of ER and NEE. We found a significant relationship between optimized V-cmax and latitude (temperature), which better reflects the spatial gradients of annual NEE than using an average V-cmax value.Peer reviewe

    Diagnostic classification of childhood cancer using multiscale transcriptomics

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    The causes of pediatric cancers’ distinctiveness compared to adult-onset tumors of the same type are not completely clear and not fully explained by their genomes. In this study, we used an optimized multilevel RNA clustering approach to derive molecular definitions for most childhood cancers. Applying this method to 13,313 transcriptomes, we constructed a pediatric cancer atlas to explore age-associated changes. Tumor entities were sometimes unexpectedly grouped due to common lineages, drivers or stemness profiles. Some established entities were divided into subgroups that predicted outcome better than current diagnostic approaches. These definitions account for inter-tumoral and intra-tumoral heterogeneity and have the potential of enabling reproducible, quantifiable diagnostics. As a whole, childhood tumors had more transcriptional diversity than adult tumors, maintaining greater expression flexibility. To apply these insights, we designed an ensemble convolutional neural network classifier. We show that this tool was able to match or clarify the diagnosis for 85% of childhood tumors in a prospective cohort. If further validated, this framework could be extended to derive molecular definitions for all cancer types
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