scholarly journals Simulation Study of Balancing Arm Arrangement for Controlling Base Disturbances in Long Reach Manipulators

Mechanika ◽  
2021 ◽  
Vol 27 (3) ◽  
pp. 220-228
Author(s):  
A. SRINIVASAN ◽  
A. JEGAN
Keyword(s):  
Hydraulic Fluid ◽  
End Effector ◽  
Serial Chain ◽  
Single Link ◽  
Long Time ◽  
Set Up ◽  
Supporting Base ◽  
Tip Mass ◽  
Base Disturbance ◽  
Base Structure

The dynamics of the Long Reach Manipulators create disturbances in its supporting base structure. This causes positional and attitude inaccuracies of the end-effector, thwarting the accomplishment of the desired mission task. Hence the base disturbance problem has been a subject of research since long time bringing solutions from varied domains. This paper analyzes the balance link concept for compensating the disturbances. The LRM system is modelled as a two-link serial chain with payload, and the balance arm, as a single link with tip mass that is dynamically varied by controlling the quantity of the hydraulic fluid in the bellows-like reservoir at the tip. The supporting base is modelled as a half car. Simultaneous constraint matrices are set up for the arrangement, and dynamic simulation is performed using SIMULINK. The pitch and bounce motions of the base are studied along with the torque error during compensation. The simulation plots are obtained for two conditions of compensating arm¾with fixed tip mass and with varying tip mass. The results confirm the suitability of the suggested compensating arrangement in controlling base disturbances.

scholarly journals Optimization of Dynamic Task Location within a Manipulator’s Workspace for the Utilization of the Minimum Required Joint Torques

Electronics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 288
Author(s):  
Adam Wolniakowski ◽  
Charalampos Valsamos ◽  
Kanstantsin Miatliuk ◽  
Vassilis Moulianitis ◽  
Nikos Aspragathos
Keyword(s):  
High Performance ◽  
Human Robot Interaction ◽  
Optimal Position ◽  
End Effector ◽  
Joint Torques ◽  
Dynamic Task ◽  
Arbitrary Position ◽  
Simulation Results ◽  
Set Up ◽  
Task Placement

The determination of the optimal position of a robotic task within a manipulator’s workspace is crucial for the manipulator to achieve high performance regarding selected aspects of its operation. In this paper, a method for determining the optimal task placement for a serial manipulator is presented, so that the required joint torques are minimized. The task considered comprises the exercise of a given force in a given direction along a 3D path followed by the end effector. Given that many such tasks are usually conducted by human workers and as such the utilized trajectories are quite complex to model, a Human Robot Interaction (HRI) approach was chosen to define the task, where the robot is taught the task trajectory by a human operator. Furthermore, the presented method considers the singular free paths of the manipulator’s end-effector motion in the configuration space. Simulation results are utilized to set up a physical execution of the task in the optimal derived position within a UR-3 manipulator’s workspace. For reference the task is also placed at an arbitrary “bad” location in order to validate the simulation results. Experimental results verify that the positioning of the task at the optimal location derived by the presented method allows for the task execution with minimum joint torques as opposed to the arbitrary position.

scholarly journals Acceptance of a Symptom-Based Approach for COVID-19 rtRT-PCR Testing to Conserve Resources in a Lower Middle-Income Setting

2021 ◽  
Vol 12 ◽  
pp. 215013272098771
Author(s):  
S. M. Rashed Ul Islam ◽  
Tahmina Akther ◽  
Md. Abdullah Omar Nasif ◽  
Sharmin Sultana ◽  
Saif Ullah Munshi
Keyword(s):  
Primary Method ◽  
Chain Reaction ◽  
Middle Income ◽  
Clinical Recovery ◽  
Clinical Presentations ◽  
Long Time ◽  
Nasopharyngeal Secretion ◽  
Polymerase Chain ◽  
Set Up

SARS-CoV-2 initially emerged in Wuhan, China in late 2019. It has since been recognized as a pandemic and has led to great social and economic disruption globally. The Reverse Transcriptase Real-Time Polymerase Chain Reaction (rtRT-PCR) has become the primary method for COVID-19 testing worldwide. The method requires a specialized laboratory set up. Long-term persistence of SARS-CoV-2 RNA in nasopharyngeal secretion after full clinical recovery of the patient is regularly observed nowadays. This forces the patients to spend a longer period in isolation and test repeatedly to obtain evidence of viral clearance. Repeated COVID-19 testing in asymptomatic or mildly symptomatic cases often leads to extra workload for laboratories that are already struggling with a high specimen turnover. Here, we present 5 purposively selected cases with different patterns of clinical presentations in which nasopharyngeal shedding of SARS-CoV-2 RNA was observed in patients for a long time. From these case studies, we emphasized the adoption of a symptom-based approach for discontinuing transmission-based precautions over a test-based strategy to reduce the time spent by asymptomatic and mildly symptomatic COVID-19 patients in isolation. A symptom-based approach will also help reduce laboratory burden for COVID-19 testing as well as conserve valuable resources and supplies utilized for rtRT-PCR testing in an emerging lower-middle-income setting. Most importantly, it will also make room for critically ill COVID-19 patients to visit or avail COVID-19 testing at their convenience.

Seven-Position Synthesis of a Spatial Eight-Bar Linkage by Constraining a TRS Serial Chain

2009 ◽  
Author(s):  
Gim Song Soh ◽  
J. Michael McCarthy
Keyword(s):  
Degree Of Freedom ◽  
Upper Arm ◽  
End Effector ◽  
Serial Chain ◽  
Position Synthesis ◽  
Two Degree Of Freedom ◽  
Puma Robot

In this paper, we use seven-position synthesis to add four TS constraints to a TRS serial chain robot and obtain a two degree-of-freedom spatial eight-bar linkage. The TRS chain is an elbow manipulator, similar to a PUMA robot. We synthesize a TS dyad to connect the base of the robot to its forearm, and then we synthesize three TS dyads that connect the upper arm of the robot to its end-effector. The result is a two degree-of-freedom spatial eight-bar linkage that moves through seven prescribed positions. It consists of a TRST loop supporting a 3TS-RS platform, which we denote as a TS-TRS-3TS spatial linkage. We formulate and solve the design equations for the TS dyads, and analyze the resulting eight-bar linkage. An example demonstrates our results.

Risk Factors for Typhoid Fever Occurrence and Recurrence in Gombe Metropolis, Gombe State, Nigeria

2021 ◽  
Vol 23 (11) ◽  
pp. 381-401
Author(s):  
Umar Abdullahi Tawfiq ◽  
◽  
Shohaimi Shamarina ◽  
Syafinaz Amin Nordin ◽  
Mohd Noor Hisham Mohd Nadzir ◽  
...  
Keyword(s):  
Risk Factors ◽  
Epidemiological Data ◽  
Simple Random Sampling ◽  
Chi Square ◽  
Long Time ◽  
Chi Square Test ◽  
The Government ◽  
Set Up ◽  
Associated Risk Factors ◽  
At Home

Typhoid is a life-threatening disease that has remained endemic in parts of Africa and Asia where its burden is elevated by the inefficiency of control efforts which have been hampered by lack of epidemiological data, among others. In Nigeria, such data is absent in most of the States like Gombe where the disease has been rife for a long time, hence, to bridge that knowledge gap, this study was set up to determine the host-associated risk factors for typhoid occurrence and recurrence in Gombe. A questionnaire that was designed and validated for this location was used to obtain data from 663 respondents using simple random sampling and analyzed using the Chi-square test for association and binomial logistic regression to obtain risk factors for typhoid occurrence and recurrence, respectively. The study revealed that occurrences were statistically significantly associated with the variables for vaccination (χ2 = 39.729, p < 0.01), having houseboy/girl (χ2 = 16.909, p < 0.01), typhoid patient at home (χ2 = 13.393, p < 0.01), hand washing before handling food (χ2 = 22.856, p < 0.01), consuming iced/frozen items (χ2 = 16.805, p < 0.01), boiling drinking water (χ2 = 49.633, p < 0.01), and eating commercially available foods/drinks (χ2 = 27.864, p < 0.01), while recurrences were statistically significantly predicted by „not sure of been vaccinated‟ (OR = 2.962, CI = 1.290 to 6.802, p < 0.01), „not having another typhoid patient at home‟ (OR = 1.799, CI = 0.998 to 3.244, p < 0.01), and „drinking unboiled water sometimes‟ (OR = 2.130, CI = 1.023 to 4.434, p < 0.01). It is believed that these findings will guide efforts by the Government for health interventions against typhoid in the study area, thus improving the quality of life for the population.

scholarly journals Highland Hill tribe language - an extinct language system needed to be saved

2020 ◽  
Vol 9 (2) ◽  
pp. 3-7
Author(s):  
Tang Minh Chau
Keyword(s):  
Root Culture ◽  
Language System ◽  
Hill Tribe ◽  
Long Time ◽  
Hill Tribes ◽  
Set Up ◽  
Culture And Language

Highland is a typical area in Vietnam with a great deal of unique things for people to study and discover. Among them are culture and language, the two reciprocal elements to create communities called Hill tribes. Original Hill tribes came to the Highland long time ago and set up their life based on their root culture until now. When studying about Hill tribes, we realize that their culture is very interesting and worth tracing. Therefore, how to conserve Hill tribes’ culture is what we need to take into consideration as soon as possible.

scholarly journals Synthesis of Spatial RPRP Closed Linkages for a Given Screw System

2011 ◽  
Vol 3 (2) ◽  
Author(s):  
Alba Perez-Gracia
Keyword(s):  
Design Method ◽  
Parallel Robots ◽  
Synthesis Problem ◽  
Dimensional Synthesis ◽  
End Effector ◽  
Serial Chain

The dimensional synthesis of spatial chains for a prescribed set of positions can be applied to the design of parallel robots by joining the solutions of each serial chain at the end-effector. This design method does not provide with the knowledge about the trajectory between task positions and, in some cases, may yield a system with negative mobility. These problems can be avoided for some overconstrained but movable linkages if the finite-screw system associated with the motion of the linkage is known. The finite-screw system defining the motion of the robot is generated by a set of screws, which can be related to the set of finite task positions traditionally used in the synthesis theory. The interest of this paper lies in presenting a method to define the whole workspace of the linkage as the input task for the exact dimensional synthesis problem. This method is applied to the spatial RPRP closed linkage, for which one solution exists.

Kinematic Synthesis of Spatial R-R Dyads for Path Following Revisited Using the Rotation Matrix Approach

1999 ◽  
Author(s):  
Venkat Krovi ◽  
G. K. Ananthasuresh ◽  
Vijay Kumar
Keyword(s):  
Linear System ◽  
Path Following ◽  
Rotation Matrix ◽  
Dimensional Synthesis ◽  
Kinematic Synthesis ◽  
End Effector ◽  
Serial Chain ◽  
Systematic Development ◽  
Matrix Vector ◽  
Selection Of

Abstract We revisit the dimensional synthesis of a spatial two-link, two revolute-jointed serial chain for path following applications, focussing on the systematic development of the design equations and their analytic solution for the three precision point synthesis problem. The kinematic design equations are obtained from the equations of loop-closure for end-effector position in rotation-matrix/vector form at the three precision points. These design equations form a rank-deficient linear system in the link-vector components. The nullspace of the rank deficient linear system is then deduced analytically and interpreted geometrically. Tools from linear algebra are applied to systematically create the auxiliary conditions required for synthesis and to verify consistency. An analytic procedure for obtaining the link-vector components is then developed after a suitable selection of free choices. Optimization over the free choices is possible to permit the matching of additional criteria and explored further. Examples of the design of optimal two-link coupled spatial R-R dyads are presented where the end-effector interpolates three positions exactly and closely approximates an entire desired path.

Application and Impact of Social Network in Modern Society

2019 ◽  
pp. 30-49 ◽  
Author(s):  
Mamata Rath
Keyword(s):  
Social Network ◽  
Social Systems ◽  
Personal Data ◽  
Modern Society ◽  
Work Culture ◽  
Security Measures ◽  
Home Office ◽  
Emerging Trends ◽  
Long Time ◽  
Set Up

Social network and its corresponding website permits a client to make a profile, set up an authorized account to create a digital representation of themselves, to select other members of the site as contacts, make connections with them, communicate and engage with these users in different social activities, etc. So, social network includes details of persons, group details, their friends list, contact list, business, affiliations, personal data, personal preferences, and historical information. In this age of smart communication and technology, most of the time people are connected with mobile smart telephones in their work culture, home, office, or any other related places. As they are constantly associated with social systems for long time, they get new posts, messages, and current refreshed news readily available in a flash. This is the constructive part of social networking that individuals consistently remain refreshed with most recent news and innovation. This chapter presents an overview of social network design, various issues, and emerging trends that are evolved simultaneously with modern age. It also presents a detail study on application and impact of social network in modern society as well as exhibits an exhaustive review of security measures in social sites.

Statistical-Mathematical Methods Used in Analysis of Trade in Industrial Products

2019 ◽  
Vol 34 ◽  
pp. 315-325
Author(s):  
Tomiță Constantin Vasile ◽  
Luminița Popescu ◽  
Cora Ionela Dăniasă ◽  
Anica Iancu ◽  
Virgil Popescu
Keyword(s):  
Dairy Products ◽  
Economic Importance ◽  
Mathematical Methods ◽  
Close Link ◽  
Human Needs ◽  
Commodity Production ◽  
The People ◽  
Long Time ◽  
Set Up ◽  
The Moment

Dairy products are of great socio-economic importance in Romania today. These products have both nutritional and economic importance. The market is the economic category of commodity production in which it expresses the totality of the sale-purchase acts viewed in an organic unit with the relations it generates and in connection with the space in which it takes place. The market originated a long time ago, being related to the moment when, in order to satisfy their existential needs, "discovered" and increasingly "conscious", the people exchanged between them, respectively collectivities, the surpluses held by each individual - individually or collectively. The exchange, set up as a means of realizing its own interests, has seen various forms and has evolved continuously, being still the foundation of all the economies of the world. The market has grown based on the amplification and diversification of human needs. The satisfaction of these needs is given by the close link between producers and consumers.

The Forced Creep Analysis of Nonmetallic Material

2012 ◽  
Vol 184-185 ◽  
pp. 692-695 ◽  
Author(s):  
Shan Qi Zeng ◽  
Zhi Jie Zhang
Keyword(s):  
Nonmetallic Material ◽  
Creep Model ◽  
Operating Life ◽  
Time Curve ◽  
Creep Properties ◽  
Creep Analysis ◽  
Material Creep ◽  
Long Time ◽  
Set Up ◽  
Force Creep

Nonmetallic material by stress which less the yield stresses long time, it would force creep. Nonmetallic materials’ operating life depended on the creep degree. The paper set up creep model using ANSYS, create the nonmetallic material creep strain-time curve, got the creep properties of nonmetallic material. To provide effective basis of calculate the nonmetal materials’ operating life.

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