scholarly journals A method for evaluating and upgrading systems with parallel structures with forced redundancy

2021 ◽  
Vol 23 (4) ◽  
pp. 770-776
Author(s):  
Edward Michlowicz ◽  
Jerzy Wojciechowski
Keyword(s):  
Mine Drainage ◽  
Human Life ◽  
Drainage System ◽  
Condition Assessment ◽  
Parallel Structure ◽  
Safety Assurance ◽  
Parallel Structures ◽  
System Components ◽  
Machine Systems ◽  
Continuous Material

The objects of the study are parallel-structure machine systems with redundancy associated with safety assurance of continuous material flow. The problem concerns systems in which the supply of materials takes place continuously (24 hours a day), and the system of operated machines must ensure the receipt and movement of the material at a strictly defined time and in the desired quantity. It is a system where the presence of a failure poses a threat to human life and environmental degradation. This paper presents a method for system condition assessment and upgrading for maintaining proper operation under conditions of continuous operation. A database of information about the current parameters of the system components (measurements, monitoring) is necessary for condition assessment. The method also uses lean techniques (including TPM). System evaluation and selection criteria for a suitable structure in terms of further operation were proposed. Exemplification was performed for an underground mine drainage system. As a part of the identification, selected parameters of the system components were measured, and their characteristics (motors, pumps, pipelines) were developed. The results of the analysis and the values of the adopted criteria were compared to the indicators for new pump sets. A two-option system upgrade was proposed, in addition to machine operating schedules, maintenance periods, and overhaul cycles.

scholarly journals Effect of acid mine drainage on dissolved rare earth elements geochemistry along a fluvial–estuarine system: the Tinto-Odiel Estuary (S.W. Spain)

2012 ◽  
Vol 43 (3) ◽  
pp. 262-274 ◽  
Author(s):  
J. Borrego ◽  
B. Carro ◽  
N. López-González ◽  
J. de la Rosa ◽  
J. A. Grande ◽  
...  
Keyword(s):  
Rare Earth ◽  
Acid Mine Drainage ◽  
Rare Earth Elements ◽  
Mine Drainage ◽  
Drainage System ◽  
Estuarine System ◽  
Mixing Zone ◽  
Heavy Rare Earth ◽  
Acid Mine ◽  
Heavy Rare Earth Elements

The concentration of rare earth elements together with Sc, Y, and U, as well as rare earth elements fractionation patterns, in the water of an affected acid mine drainage system were investigated. Significant dissolved concentrations of the studied elements were observed in the fluvial sector of this estuary system (Sc ∼ 31 μg L−1, Y ∼ 187 μg L−1, U ∼ 41 μg L−1, Σ rare earth elements ∼621 μg L−1), with pH values below 2.7. In the mixing zone of the estuary, concentrations are lower (Sc ∼ 2.1 μg L−1; Y ∼ 16.7 μg L−1; U ∼ 4.8 μg L−1; Σ rare earth elements ∼65.3 μg L−1) and show a strong longitudinal gradient. The largest rare earth elements removal occurs in the medium-chlorinity zone and it becomes extreme for heavy rare earth elements, as observed for Sc. Samples of the mixing zone show a North American Shale normalized pattern similar to the fluvial zone water, while the samples located in the zone with pH between 6.5 and 7.7 show a depletion of light rare earth elements relative to middle rare earth elements and heavy rare earth elements, similar to that observed in samples of the marine estuary.

scholarly journals THE DIFFICULTIES FACED BY THE STUDENTS IN ANSWERING THE WRITTEN EXPRESSION SECTION OF THE TOEFL TEST

2018 ◽  
Vol 3 (2) ◽  
Author(s):  
Mainar Fitri
Keyword(s):  
Quantitative Research ◽  
Written Expression ◽  
Parallel Structure ◽  
Study Program ◽  
Verb Agreement ◽  
The Third ◽  
Parallel Structures ◽  
Passive Verbs ◽  
Passing Grade

TOEFL test is one of the requirements for the students of English Study Program FKIP UNRI to finish their study at S1 Degree.  Based on the researcher’s observation, most of the students did not pass the TOEFL Test.  The students followed the test for several times till they reached the passing grade. It seemed that the students got difficulties in answering the TOEFL Test. So, in this research the researcher focused on analyzing the students’ difficulties in answering the Written Expression section of the TOEFL test.  The aims of this research were to identify the categories of items in the Written Expression section of the TOEFL test which were difficult for the third-year students of English Study Program FKIP-UNRI . and to identify which categories of items that were easy for the students. This research was a quantitative research. The researcher analyzed the categories of items tested in TOEFL test, especially in the Written Expression section. There were 12 categories of items tested in the Written Expression section of the TOEFL test based on Longman Preparation Course for the TOEFL Test by Deborah Phillips (2000: 144-221). The categories consisted of subject-verb agreement, parallel structure, comparative and superlative, the use of the verbs, the forms of the verbs, passive verbs, nouns, pronouns, adjectives and adverbs, articles, prepositions and usages   The result of the research showed that there were 10 categories of items that were difficult for the students. The categories were parallel structures, comparatives and superlatives, the use of the verbs, passive verbs, nouns, pronouns, adjectives and adverbs, articles, prepositions and usages.  While the categories of items which were considered easy for the students were subject-verb agreement and the forms of the verbs. So, in general, the students got difficulties in answering the Written Expression section of the TOEFL test.

Position Kinematics of a Three-Limbed Mixed Mechanism

1994 ◽  
Vol 116 (3) ◽  
pp. 924-929 ◽  
Author(s):  
M. Husain ◽  
K. J. Waldron
Keyword(s):  
Rational Design ◽  
Industrial Robots ◽  
Parallel Structure ◽  
General Mechanism ◽  
Static Characteristics ◽  
Serial Chain ◽  
Hybrid Mechanism ◽  
Parallel Structures ◽  
Industrial Use ◽  
Mixed Mechanism

Although robotics has traditionally focused on the serial chain structures typical of industrial robots, fully parallel structures such as the Stewart Platform have also found considerable industrial use. Actively coordinated mechanisms which have combinations of serial and parallel characteristics have been practically employed, and can be expected to become more important in the future. There has been very little study of the kinematic and static characteristics of these mechanisms which have combinations of the characteristics of fully serial and fully parallel structures. This work addresses the direct and inverse position kinematics of such a hybrid mechanism with combination of serial and parallel structure which has multiple, actively controlled actuators. While not the most general possible configuration, this particular case does include many important features of the general mechanism, and the solution obtained gives useful insight for developing a general theory of forward and inverse kinematics which will be equally applicable to serial, parallel and combination structures. Such a theory is necessary for rational design of hardware and software for such systems.

Man-Machine Photogrammetric Systems and System Components

1973 ◽  
Vol 27 (4) ◽  
pp. 308-319 ◽  
Author(s):  
Z. Jaksic
Keyword(s):  
Data Processing ◽  
Research Council ◽  
Communication Theory ◽  
National Research Council ◽  
The Other ◽  
System Components ◽  
Two Systems ◽  
Machine Systems

Under the influence of ideas from control and communication theory, new trends have developed in the design of photogrammetric data-processing systems. In this paper a number of concepts applied to the design of such systems are discussed, with emphasis on the digital man-machine systems and system components. The main characteristics of contemporary photogrammetric systems are outlined in regard to both their hardware and software, including some remarks on automation and orthophototechniques. The general descriptions are supported by examples from two systems: one predominantly digital and the other predominantly analog. These examples concern the instrumental developments in the Photogrammetric Research Laboratories of the National Research Council of Canada.

Arsenic removal by oxidizing bacteria in a heavily arsenic-contaminated acid mine drainage system (Carnoulès, France)

2002 ◽  
Vol 198 (1) ◽  
pp. 267-274 ◽  
Author(s):  
Marc Leblanc ◽  
Corinne Casiot ◽  
Françoise Elbaz-Poulichet ◽  
Christian Personné
Keyword(s):  
Acid Mine Drainage ◽  
Arsenic Removal ◽  
Mine Drainage ◽  
Drainage System ◽  
Acid Mine

Microbially enhanced dissolution of HgS in an acid mine drainage system in the California Coast Range

Geobiology ◽  
2013 ◽  
Vol 12 (1) ◽  
pp. 20-33 ◽  
Author(s):  
A. D. Jew ◽  
S. F. Behrens ◽  
J. J. Rytuba ◽  
A. Kappler ◽  
A. M. Spormann ◽  
...  
Keyword(s):  
Acid Mine Drainage ◽  
Mine Drainage ◽  
Drainage System ◽  
Coast Range ◽  
California Coast ◽  
Acid Mine ◽  
Enhanced Dissolution

The Research and Development of the Coal Mine Underground Drainage Equipment Automatic Control System

2014 ◽  
Vol 1049-1050 ◽  
pp. 1038-1041
Author(s):  
Zhang Meng ◽  
Tao Zhu Feng ◽  
Guo Feng
Keyword(s):  
Control System ◽  
Service Life ◽  
Research And Development ◽  
Coal Mine ◽  
Mine Drainage ◽  
Drainage System ◽  
Labor Intensity ◽  
Relay Control ◽  
Coal Mine Drainage ◽  
Plc Control

The coal mine drainage equip ment plays an important role to make the production normally and orderly. At present, domestic coal mine drainage system implement manual monitoring, namely the traditional relay control method.Feature of this method is that a large labor intensity, low reliability and stability,and complicated control circuit,it has not adapted to the needs of the development of coal.In this paper, design of the automatic drainage system is to make up for the shortage of the traditional relay control,it adopts PLC control with a combination of PC monitor to improve the safety of the work,and has a long service life, convenient maintenance, etc.

Helical Kirigami-Enabled Centimeter-Scale Worm Robot With Shape-Memory-Alloy Linear Actuators

2015 ◽  
Vol 7 (2) ◽  
Author(s):  
Ketao Zhang ◽  
Chen Qiu ◽  
Jian S. Dai
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Degrees Of Freedom ◽  
Screw Theory ◽  
Kinematic Model ◽  
Parallel Structure ◽  
Geometrical Parameters ◽  
Parallel Structures ◽  
Complete Procedure ◽  
Motion Characteristics

The wormlike robots are capable of imitating amazing locomotion of slim creatures. This paper presents a novel centimeter-scale worm robot inspired by a kirigami parallel structure with helical motion. The motion characteristics of the kirigami structure are unravelled by analyzing the equivalent kinematic model in terms of screw theory. This reveals that the kirigami parallel structure with three degrees-of-freedom (DOF) motion is capable of implementing both peristalsis and inchworm-type motion. In light of the revealed motion characteristics, a segmented worm robot which is able to imitate contracting motion, bending motion of omega shape and twisting motion in nature is proposed by integrating kirigami parallel structures successively. Following the kinematic and static characteristics of the kirigami structure, actuation models are explored by employing the linear shape-memory-alloy (SMA) coil springs and the complete procedure for determining the geometrical parameters of the SMA coil springs. Actuation phases for the actuation model with two SMA springs are enumerated and with four SMA springs are calculated based on the Burnside's lemma. In this paper, a prototype of the worm robot with three segments is presented together with a paper-made body structure and integrated SMA coil springs. This centimeter-scale prototype of the worm robot is lightweight and can be used in confined environments for detection and inspection. The study presents an interesting approach of integrating SMA actuators in kirigami-enabled parallel structures for the development of compliant and miniaturized robots.

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