scholarly journals Research on Catastrophic Pillar Instability in Room and Pillar Gypsum Mining

2018 ◽  
Vol 10 (10) ◽  
pp. 3773 ◽  
Author(s):  
Yuejin Zhou ◽  
Meng Li ◽  
Xiaoding Xu ◽  
Xiaotong Li ◽  
Yongdong Ma ◽  
...  
Keyword(s):  
Rock Mass ◽  
Constitutive Equation ◽  
Safety Factor ◽  
Sufficient Conditions ◽  
Pillar Stability ◽  
Room And Pillar Mining ◽  
History Of ◽  
Gypsum Rock ◽  
Pillar Mining ◽  
Necessary And Sufficient

Gypsum mines in China are mostly exploited through room and pillar mining. Due to backward mining technology and a long history of mining, a great number of pillars were left in gypsum mines. Many serious work safety accidents occurred as the result of goaf instability in history, which posed severe threats to the security of people’s lives and property. Based on the characteristics of surrounding rock damage, this research improved the constitutive equation of gypsum rock mass damage by establishing a damage evolution model and introducing a shape parameter. Meanwhile, the cusp catastrophe equation was deduced based on the catastrophe theory and the constitutive equation of gypsum rock mass damage, thus summarizing the criteria for pillar instability; the pillar safety factor was obtained by means of the interrelation between pillar load and pillar strength. Based on the criteria for pillar instability and the pillar safety factor obtained, the necessary and sufficient conditions for pillar stability were concluded. These conclusions are of significance in that they provide theoretic reference for the treatment of gypsum goaf, as well as for further mining.

scholarly journals Regime and Sociology: A Comparative History of Sociology in Postwar Europe with Qualitative Comparative Analysis

2021 ◽  
pp. 1-30
Author(s):  
Matthias Duller
Keyword(s):  
Comparative Analysis ◽  
Qualitative Comparative Analysis ◽  
Sufficient Conditions ◽  
Political Regime ◽  
Context Sensitive ◽  
Postwar Europe ◽  
Regime Types ◽  
History Of ◽  
Continuous Presence ◽  
Necessary And Sufficient

Abstract Using Qualitative Comparative Analysis, this article presents a systematic comparison of differences in the institutional success of sociology in 25 European countries during the academic expansion from 1945 until the late 1960s. Combining context-sensitive national histories of sociology, concept formation, and formal analyses of necessary and sufficient conditions, the article searches for historical explanations for both successful and inhibited processes of the institutionalization of sociology. Concretely, it assesses the interplay of political regime types, the continuous presence of sociological prewar traditions, political Catholicism, and the effects of sociological communities in neighboring countries and how their various combinations are related to more or less well-established sociologies. The results can help explain adversary effects under democratic conditions as well as supportive factors under nondemocratic conditions.

scholarly journals Peningkatan Kestabilan Pilar Tambang Bawah Tanah Marmer di PT Gunung Marmer Raya

2020 ◽  
Vol 3 (1) ◽  
pp. 27-38
Author(s):  
Purwanto Purwanto
Keyword(s):  
Rock Mass ◽  
Safety Factor ◽  
Underground Mining ◽  
Underground Mine ◽  
Joint Movement ◽  
Pillar Stability ◽  
The North ◽  
Joint Monitoring ◽  
The Stability ◽  
Q System

PT Gunung Marmer Raya  (PT GMR), a room and pillar underground marble mining is located about  73 km to the north from Makassar, in Desa Tabo-Tabo, Kecamatan Bungoro, Kabupaten Pangkep. In the mining location, discontinuities are found as joint structure across the production area. The purpose of this service is to make pillar redesign that can improve the stability of underground mine. These activities start with field observation, determining the rock characteristic through sample testing in the laboratory, classifying the rock mass using Q-system method, up to redesigning a form of implementation to increase the stability of the marble underground mine. According to calculation of rock mass classification using Q-System, the recommended buffering is systematic bolting and fiber reinforced sprayed concrete as thick as 5-6 cm with spacing between bolts of 2.2 meters, or systematic bolting without concrete layering with spacing between-bolt 1.8 meter. Joint monitoring, especially on pillars, need to be done routinely so joint movement could be anticipated for progressive movement. The existing dimensions of pillar 5 m x 5 m in length and width is not recommended due to the safety factor is under 1,0  (unstable condition). Based on observation and analytic calculation, for each pillar height of up to 11 meters the pillar is recommended to redesign with length and width 5 m x 9 m for the chain pillar (safety factor around 1.35-1.49); and 5 m x 12 m for barrier pillars (safety factor around 1.58-1.74). Key Words: Underground mining; room and pillar method; Q-system classification system; pillar stability; marble mining.

Chapter 1. A History of Satisfiability

2021 ◽  
Author(s):  
John Franco ◽  
John Martin
Keyword(s):  
Propositional Logic ◽  
Scientific Discovery ◽  
Sufficient Conditions ◽  
Human Reasoning ◽  
History Of ◽  
Electronic Computers ◽  
Necessary And Sufficient ◽  
Working Out ◽  
Algebraic Approaches

This chapter traces the links between the notion of Satisfiability and the attempts by mathematicians, philosophers, engineers, and scientists over the last 2300 years to develop effective processes for emulating human reasoning and scientific discovery, and for assisting in the development of electronic computers and other electronic components. Satisfiability was present implicitly in the development of ancient logics such as Aristotle’s syllogistic logic, its extentions by the Stoics, and Lull’s diagrammatic logic of the medieval period. From the renaissance to Boole algebraic approaches to effective process replaced the logics of the ancients and all but enunciated the meaning of Satisfiability for propositional logic. Clarification of the concept is credited to Tarski in working out necessary and sufficient conditions for “p is true” for any formula p in first-order syntax. At about the same time, the study of effective process increased in importance with the resulting development of lambda calculus, recursive function theory, and Turing machines, all of which became the foundations of computer science and are linked to the notion of Satisfiability. Shannon provided the link to the computer age and Davis and Putnam directly linked Satisfiability to automated reasoning via an algorithm which is the backbone of most modern SAT solvers. These events propelled the study of Satisfiability for the next several decades, reaching “epidemic proportions” in the 1990s and 2000s, and the chapter concludes with a brief history of each of the major Satisfiability-related research tracks that developed during that period.

Operational control of rib pillar stability

2020 ◽  
pp. 7-10
Author(s):  
A. A. Baryah ◽  
◽  
A. V. Evseev ◽  
I. S. Lomakin ◽  
A. A. Tsayukov ◽  
...  
Keyword(s):  
Rock Mass ◽  
Transverse Deformation ◽  
Russian Science ◽  
Mining Operations ◽  
Pillar Stability ◽  
Room And Pillar Mining ◽  
Salt Mines ◽  
Potash Salt ◽  
Monitoring Procedure ◽  
Mining Safety

In room-and-pillar mineral mining, rib pillars should support overlying rock mass for the specified time limit of production. Therefore, one of the mining safety components is monitoring of the behavior of rib pillars in the course of time. For the conditions of the room-andpillar method of mining, the authors propose a monitoring procedure for rib pillar deformation based on operational measurements of horizontal convergence in stopes. The theoretical and experimental research proves that transverse deformation of rib pillars is an informative parameter suitable for generalized assessment of pillar failure. The obtained ranges of critical transverse deformation rates (50–100 mm/m/yr) in rib pillars can tentatively be used as an indicator of the critical stability of load-bearing structures in room-and-pillar mining. In-situ determination of the integral transverse deformation rates in rib pillars is based on the ratio of the measured horizontal convergence in stopes to the width of pillars. Implementation of the proposed approach in the Upper Kama potash salt mines has proved its applicability to identification of rock mass areas where intense deformation is expected. The comparison of the monitoring data of the transverse deformation rates and their critical values determined makes it possible to predict service life of rib pillars, which is very important in terms of safety of mining operations. This study was supported by the Russian Science Foundation, Grant No. 19-77-30008.

scholarly journals WHAT, IF ANYTHING, IS MAHĀYĀNA BUDDHISM? PROBLEMS OF DEFINITIONS AND CLASSIFICATIONS

Numen ◽  
2002 ◽  
Vol 49 (4) ◽  
pp. 355-405 ◽  
Author(s):  
Jonathan Silk
Keyword(s):  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Mahayana Buddhism ◽  
Alternative Employment ◽  
History Of ◽  
Mahāyāna Buddhism ◽  
Definition Of ◽  
Necessary And Sufficient

AbstractThis study investigates some problems regarding the definition of Mahāyāna Buddhism. Tracing the history of the notion in modern scholarship, it pays particular attention to the question of the relation between Mahāyāna and so-called Hīnayāna or Sectarian Buddhism. Finding the commonly used methods of classification which rely on necessary and sufficient conditions to be inadequate to the task, it suggests the alternative employment of polythetic classification, a method which permits a constantly variable set of questions and data to be taken into account in the most flexible and accommodating manner.

The extinction time of a general birth and death process with catastrophes

1986 ◽  
Vol 23 (04) ◽  
pp. 851-858 ◽  
Author(s):  
P. J. Brockwell
Keyword(s):  
Laplace Transform ◽  
Size Distribution ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Death Process ◽  
Extinction Time ◽  
Birth And Death Process ◽  
Different Types ◽  
The Laplace Transform ◽  
Necessary And Sufficient

The Laplace transform of the extinction time is determined for a general birth and death process with arbitrary catastrophe rate and catastrophe size distribution. It is assumed only that the birth rates satisfyλ0= 0,λj> 0 for eachj> 0, and. Necessary and sufficient conditions for certain extinction of the population are derived. The results are applied to the linear birth and death process (λj=jλ, µj=jμ) with catastrophes of several different types.

Budgeting in Socio-economic Development Strategies (Raising a Problem)

2008 ◽  
pp. 134-151
Author(s):  
A. Shastitko ◽  
M. Ovchinnikov
Keyword(s):  
Economic Policy ◽  
Economic Development ◽  
Social Change ◽  
Eastern Europe ◽  
Statistical Data ◽  
Sufficient Conditions ◽  
Transitional Period ◽  
Socio Economic Development ◽  
Necessary And Sufficient ◽  
Economic Development Strategies

The article proposes an approach to the analysis of social change and contributes to the clarification of concepts of economic policy. It deals in particular with the notion of "change of system". The author considers positive and normative aspects of the analysis of capitalist and socialist systems. The necessary and sufficient conditions for the system to be changed are introduced, their fulfillment is discussed drawing upon the historical and statistical data. The article describes both economic and political peculiarities of the transitional period in different countries, especially in Eastern Europe.

Inventory optimization considering the vehicle capacity and specifics of cash flows at rental storage sites

2020 ◽  
pp. 77-90
Author(s):  
V.D. Gerami ◽  
I.G. Shidlovskii
Keyword(s):  
Supply Chain ◽  
Inventory Management ◽  
Sufficient Conditions ◽  
Cash Flows ◽  
Management Systems ◽  
Cargo Capacity ◽  
Special Modification ◽  
The Cost ◽  
Necessary And Sufficient ◽  
Vehicle Capacity

The article presents a special modification of the EOQ formula and its application to the accounting of the cargo capacity factor for the relevant procedures for optimizing deliveries when renting storage facilities. The specified development will allow managers to take into account the following process specifics in the format of a simulated supply chain when managing inventory. First of all, it will allow considering the most important factor of cargo capacity when optimizing stocks. Moreover, this formula will make it possible to find the optimal strategy for the supply of goods if, also, it is necessary to take into account the combined effect of several factors necessary for practice, which will undoubtedly affect decision-making procedures. Here we are talking about the need for additional consideration of the following essential attributes of the simulated cash flow of the supply chain: 1) time value of money; 2) deferral of payment of the cost of the order; 3) pre-agreed allowable delays in the receipt of revenue from goods sold. Developed analysis and optimization procedures have been implemented to models of this type that are interesting and important for a business. This — inventory management systems, the format of which is related to the special concept of efficient supply. We are talking about models where the presence of the specified delays for the outgoing cash flows allows you to pay for the order and the corresponding costs of the supply chain from the corresponding revenue on the re-order interval. Accordingly, the necessary and sufficient conditions are established based on which managers will be able to identify models of the specified type. The purpose of the article is to draw the attention of managers to real opportunities to improve the efficiency of inventory management systems by taking into account these factors for a simulated supply chain.

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