Master Operator Research Articles

Exploring the challenges and opportunities for master operators and water kiosks under Delegated Management Model (DMM): A study in Lake Victoria region, Kenya

The urban poor in developing nations lack access to basic services, including access to clean water. Utility–community partnerships, for instance, the Delegated Management Model (DMM) in which a utility delegates management of infrastructure and service delivery to slum communities, are often promoted as a viable solution to accelerate slum community access to water services. However, little empirical research has been done to evaluate the benefits and challenges of such models. This study compared water services using the Institutional Analysis and Development (IAD) Framework in three slums in Kisumu city, Kenya: two where DMM has been implemented, and one where it has not. Results showed that DMM had slightly lowered water costs for slum dwellers, and improved revenue collection from the operators. However, despite these benefits, access to water had not significantly improved; unreliability of services was a problem. Implementing DMM in crowded settlements inadvertently resulted in service network that was prone to unintentional damage. Unreliability of services was caused by frequent pipe bursts often due to unintentional sources, for instance, pipe breakage by vehicles, poor maintenance, and vandalism. Weak and uncoordinated institutional arrangements affected the effectiveness of operators’ efforts to curb these system disruptions, thus exacerbating sub-optimal service delivery. Moreover, the unreliability of services in DMM serviced settlements can exacerbate the health problems that the urban poor face due to the very poor water quality of sources that residents use during periods of system outages. External support is needed to hasten the development of practical solutions that fit the social and geophysical character of individual slum communities in order to improve service reliability.

Open quantum reaction-diffusion dynamics: Absorbing states and relaxation.

We consider an extension of classical stochastic reaction-diffusion (RD) dynamics to open quantum systems. We study a class of models of hard-core particles on a one-dimensional lattice whose dynamics is generated by a quantum master operator. Particle hopping is coherent while reactions, such as pair annihilation or pair coalescence, are dissipative. These are quantum open generalizations of the A+A→⌀ and A+A→A classical RD models. We characterize the relaxation of the state towards the stationary regime via a decomposition of the system Hilbert space into transient and recurrent subspaces. We provide a complete classification of the structure of the recurrent subspace (and the nonequilibrium steady states) in terms of the dark states associated to the quantum master operator and its general spectral properties. We also show that, in one dimension, relaxation towards these absorbing dark states is slower than that predicted by a mean-field analysis due to fluctuation effects, in analogy with what occurs in classical RD systems. Numerical simulations of small systems suggest that the decay of the density in one dimension, in both the open quantum A+A→⌀ and A+A→A systems, behaves asymptotically as t-b with 1/2<b<1.

1P2-I10 操作対象の位置姿勢の直接操作によるマスタスレーブシステム

The demand of robots, which is to work under the hazardous environment scene instead of human, is getting increased in recent years. Such robots should be controlled directly by human operators to make flexible decisions under such conditions, so our study is to develop the system of using master-slave with high maneuverable master device. In this research we propose a new method of master-slave operation with manipulating multiple numbers of slave robots by single master operator. In particular, the method is to transfer the coordinate system of operator's hand directly to the manipulated object, but not to robot's hand. It is efficient in some situations which is found difficulty with using only one slave robot, such that handling a large object. Moreover, we aimed to realize the proposed system without a feeling of wrongness, by evaluating the movability of the slave arm, using Gaussian Mixture Model of the hand's movable area.

Study on Control Strategy of Microgrid in Islanded Operation Mode

The droop control strategy is only considered the frequency stability during the islanded operation mode of microgrid. So a cooperative control strategy based on two-layer hierarchical control structure is proposed in this paper. In islanded operation mode, Single master operation (SMO) or multi master operation (MMO) is decided by microgrid management system (MMS). When power changes during islanded operation, the master unit (s) with v/f control can balance the energy production and consumption quickly. Based on detecting instantaneous power of master unit (s),The secondary control of MMS sets renewed reference values of instantaneous power of slave unit (s) with PQ control. After that the output power of master unit (s) will return into zero. The simulation studies demonstrate that the proposed cooperative control strategy not only implements no-error frequency control and voltage stability control, but also provides enough spinning reserve margin for master unit (s) to keep the system energy balance all the time.

Repulsive force control of minimally invasive surgery robot associated with three degrees of freedom electrorheological fluid-based haptic master

This paper presents a repulsive force feedback control in a haptic master–slave robot-assisted system for robot minimally invasive surgery. In general, the haptic master can provide position and force information for superior performance and reliability in master–slave robot-assisted interventions for a surgeon. In order to realize this potential, in this work three degrees of freedom electrorheological haptic master is adopted and associated with a four degrees of freedom slave robot. The haptic master featuring controllable electrorheological fluid is featured by a spherical joint mechanism and the slave robot is controlled by servomotors. After designing a user interface that is capable of providing force feedback in all the degrees of freedom available during robot minimally invasive surgery, the dynamic model of the haptic master is analyzed and the model parameters are identified to evaluate control performance of the haptic master on skin- and cancer-like tissues (palpation). Subsequently, the haptic architecture for robot minimally invasive surgery is established and experimentally implemented so that the reflection force for the object of the slave robot and the desired position for the master operator are transferred to each other. In order to demonstrate the effectiveness of the proposed system, repulsive force tracking control performances are evaluated and presented in time domain.

Development of a vision non-contact sensing system for telerobotic applications

The study presented here describes a novel vision-based motion detection system for telerobotic operations such as distant surgical procedures. The system uses a CCD camera and image processing to detect the motion of a master robot or operator. Colour tags are placed on the arm and head of a human operator to detect the up/down, right/left motion of the head as well as the right/left motion of the arm. The motion of the colour tags are used to actuate a slave robot or a remote system. The determination of the colour tags’ motion is achieved through image processing using eigenvectors and colour system morphology and the relative head, shoulder and wrist rotation angles through inverse dynamics and coordinate transformation. A program is used to transform this motion data into motor control commands and transmit them to a slave robot or remote system through wireless internet. The system performed well even in complex environments with errors that did not exceed 2 pixels with a response time of about 0.1 s. The results of the experiments are available at: http://www.youtube.com/watch?v=yFxLaVWE3f8 and http://www.youtube.com/watch?v=_nvRcOzlWHw

Evolution of operations planning and control: from production to supply chains

The focus of operations planning and control for manufacturing firms has expanded successively over the last 50 years. New principles, techniques, and systems have emerged that have allowed for new approaches. The perspective for planning and control has expanded from internal production operations to supply chain operations linking suppliers, manufacturers, and customers. In this paper, we take a historical perspective identifying the key trends and focus shifts in the evolution of planning and control, from shop floor control through material requirements planning (MRP), master production scheduling (MPS), and sales and operations planning (S&OP) to supply chain planning (SCP).

Force Feedback Manipulating System for Neurosurgery

For the application to the resection of brain tumor, force detecting micro gripper and force feedback system has been developed. Grasping force and pulling force at the gripper are transmitted to the master operating system where the surgeon feel the gr ipping force as force resistance and pulling force as friction on the finger surface.The feeling at the master operator has been investigated through the gripping test on soft materials in various hardness applying force reflection bilateral control program. Topics: OS2: Medical devices and medical tools.

Optimal design of a new 3D haptic gripper for telemanipulation, featuring magnetorheological fluid brakes

In this research work, a new configuration of a 3D haptic gripper for telemanipulation is proposed and optimally designed. The proposed haptic gripper, featuring three magnetorheological fluid brakes (MRBs), reflects the rolling torque, the grasping force and the approach force from the slave manipulator to the master operator. After describing the operational principle of the haptic gripper, an optimal design of the MRBs for the gripper is performed. The purpose of the optimization problem is to find the most compact MRB that can provide a required braking torque/force to the master operator while the off-state torque/force is kept as small as possible. In the optimal design, different types of MRBs and different MR fluids (MRFs) are considered. In order to obtain the optimal solution of the MRBs, an optimization approach based on finite element analysis (FEA) integrated with an optimization tool is used. The optimal solutions of the MRBs are then obtained and the optimized MRBs for the haptic gripper are identified. In addition, discussions on the optimal solutions and performance of the optimized MRBs are given.

와이어 구동방식 원격조작기용 그리퍼의 반자동 파지 및 해제 동작을 위한 스프링 강성 분석

Remote handling manipulators are widely used for performing hazardous tasks, and it is essential to ensure the reliable performance of such systems. Toward this end, tendon-driven mechanisms are adopted in such systems to reduce the weight of the distal parts of the manipulator while maintaining the handling performance. In this study, several approaches for the design of a gripper system for a tendon-driven remote handling system are introduced. Basically, this gripper has an underactuated spring mechanism that is combined with a slave manipulator triggered by a master operator. Based on the requirements under the specified tendon-driven mechanism, the connecting position of the spring system on the gripper mechanism and kinematic influence coefficient (KIC) analysis are performed. As a result, a suitable combination of components for the proper design of the target system is presented and verified.

Tele-impedance: Teleoperation with impedance regulation using a body–machine interface

This work presents the concept of tele-impedance as a method for remotely controlling a robotic arm in interaction with uncertain environments. As an alternative to bilateral force-reflecting teleoperation control, in tele-impedance a compound reference command is sent to the slave robot including both the desired motion trajectory and impedance profile, which are then realized by the remote controller without explicit feedback to the operator. We derive the reference command from a novel body–machine interface (BMI) applied to the master operator’s arm, using only non-intrusive position and electromyography (EMG) measurements, and excluding any feedback from the remote site except for looking at the task. The proposed BMI exploits a novel algorithm to decouple the estimates of force and stiffness of the human arm while performing the task. The endpoint (wrist) position of the human arm is monitored by an optical tracking system and used for the closed-loop position control of the robot’s end-effector. The concept is demonstrated in two experiments, namely a peg-in-the-hole and a ball-catching task, which illustrate complementary aspects of the method. The performance of tele-impedance control is assessed by comparing the results obtained with the slave arm under either constantly low or high stiffness.

A Cross-Coupled Master–Slave Interleaving Method for Boundary Conduction Mode (BCM) PFC Converters

This paper proposes a cross-coupled master-slave interleaving control method for boundary conduction mode (BCM) power factor correction (PFC) converters. The natural period of every switching cycle of each channel is measured and compared to adaptively determine the master and slave converters, where a converter with a longer natural period becomes master operating in BCM, while a converter with a shorter natural period becomes slave operating in discontinuous conduction mode. The proposed method compensates disturbances within one switching cycle, guaranteeing stable 180° out-of-phase interleaving operation against any transient and disturbance. The proposed method has been implemented and tested on a 400 W interleaved BCM boost PFC prototype converter with a dedicated control IC.

Anomalies in the ERG Approach

The antifield formalism adapted in the exact renormalization group is found to be useful for describing a system with some symmetry, especially the gauge symmetry. In the formalism, the vanishing of the quantum master operator implies the presence of a symmetry. The QM operator satisfies a simple algebraic relation that will be shown to be related to the Wess-Zumino condition for anomalies. We also explain how an anomaly contributes to the QM operator.

Expanding the base for teaching of percutaneous coronary interventions: The explicit approach

Accelerate and improve the training and learning process of operators performing percutaneous coronary interventions (PCI). Operator cognitive, in particular decision-making skills and technical skills are a major factor for the success of coronary interventions. Currently, cognitive skills are commonly developed by three methods: (1) Cognitive learning of rules for which statistical evidence is available. This is very incomprehensive and isolates cognitive learning from skill acquisition. (2) Informal tutoring received from experienced operators, and (3) personal experience by trial-and-error are both very slow. We propose in this concept article a conceptual framework to elicit, capture, and transfer expert PCI skills to complement the current approach. This includes the development of an in-depth understanding of the nature of PCI skills, terminology, and nomenclature needed to streamline communication, propensity of reproducible performance assessment, and in particular an explication of intervention planning and intra-intervention decision-making. We illustrate the impact of improved decision-making by simulation results based on a stochastic model of intervention risk. We identify several key concepts that form the basis of this conceptual framework, in particular different risk types and the notions of strategy, interventional module, and tactic. The increasing complexity of cases have brought PCI to the point where the decision-making skills of master operators need to be made explicit to make them systematically learnable such that the skills of beginner and intermediate operators can be improved much faster than is currently possible.

Neurosurgical robotic system for brain tumor removal

Brain tumor (e.g., glioma) resection surgery, representing the first step for many treatments, is often difficult and time-consuming for neurosurgeons. Thus, intelligent neurosurgical instruments have been developed to improve tumor removal. The concept and robotic structure of intelligent neurosurgical instruments were introduced. These instruments consist of a surgical robot, a master device and operating software. The robot incorporates a surgical motion base and tool manipulator, including a volume control suction tool. Open Core Control software was developed for connecting intelligent neurosurgical instruments through a network connection and integrating the instruments into a system. Mechanical evaluation tests on the components and a preliminary system evaluation were performed. A phantom model was fixed on a head frame, and a tumor-removal procedure was successfully performed using prototype intelligent neurosurgical instruments. Intelligent neurosurgical instruments are feasible and suitable for on-going evaluation in practical tasks, including in-vivo animal testing.

2A1-C05 低侵襲脳外科手術における術野確保 : 訓練用シミュレータと力覚提示マスタの開発

This paper describes the development and experimental results of a master manipulator for the workspace-creation manipulator for minimally invasive brain surgery. This master manipulator was developed for the purpose of maximizing the doctor's facility for performing operations. Therefore, the master manipulator needs to be easy to use for the doctor. This master increased by information offered to the doctor by the inner force power sense presentation mechanism. Moreover, the simulator in which the brain was assumed to be a model was made, and the training of the master operation was enabled. This model was made in consideration of physical properties of the brain.

General formulation for direct evaluation of the local field amplitude and transition amplitude based on the Fredholm determinant

We develop a determinantal method in a quantum scattering system for direct evaluation of various quantities including the local field amplitude and transition amplitude ($S$-matrix element). This method is applicable to multichannel elastic and inelastic scattering systems without rearranging the particles. The underlying principle of our formulation is that requested information can be extracted from a wave operator without solving the wave equation. The wave operator is the master operator maintaining all of the information about a system; the determinant of the inverse wave operator is just the Fredholm determinant. In the 1960s, a similar determinantal method was developed for the $S$-matrix element or equivalently the far-field amplitude of the wave function. Until now, however, no determinantal method for near-field quantities existed, although de Broglie and electromagnetic near fields are observable using scanning probe microscopes. Additionally, we prove that our formula for $S$-matrix element covers the known formula (the Le Couteur-Newton formula).

Random dynamics of gene transcription activation in single cells

The recent measurements of gene transcription activity at single cell resolution revealed that genes are often transcribed randomly and discontinuously. In order to elucidate how the environmental signals contribute to the stochasticity of gene transcription, a random transition model was recently proposed [M. Tang, The mean and noise of stochastic gene transcription, J. Theor. Biol. 253 (2008) 271–280; M. Tang, The mean frequency of transcriptional bursting and its variation in single cells, J. Math. Biol. (2009) doi:10.1007/s00285-009-0258-7, in press; published online: March 10, 2009]. In this model it is assumed that the transcription system transits randomly between three different functional states, quantifying the timing and strength of gene transcription by a sequence of probability functions P n x ( t ) , coupled in an infinite differential system of master equations. Here n ⩾ 1 are integers and x specifies each of the three functional states. In this work we further study this model aiming to understand the stochastic dynamics of gene transcription. When n ⩽ 3 , the exact form of P n x ( t ) is found analytically by solving the system of master equations. For larger n however, it is unfeasible to find P n x ( t ) explicitly, so we explore the properties of probability functions by analyzing the master operator L that transforms P ( n − 1 ) x ( t ) to P n x ( t ) . We prove that L “mollifies” the behavior of P ( n − 1 ) x ( t ) by increasing its order of differentiability and by flattening its growth globally. We also show that the n-th cycle of transcription activity condenses at distinct peak instants, with a decreasing peak strength with respect to n. The timings of these peak instants are estimated and several further open questions toward a general theory are discussed.

The mean frequency of transcriptional bursting and its variation in single cells

The recent in vivo RNA detection technique has allowed real-time monitoring of gene transcription in individual living cells, revealing that genes can be transcribed randomly in a bursting fashion that short periods of rapid production of multiple transcripts are interspersed with relatively long periods of no production. In this work, we utilize the three state model to study how environmental signals and the intrinsic cellular contexts are combined to regulate stochastic gene transcription. We introduce a system of three master equations to model the stochastic occurrence of transcriptional bursting. As this system cannot be solved analytically, we introduce a linear operator, called the master operator. It is of significant mathematical interests of its own and transforms the mean frequency of transcriptional bursting mu(t) and the second moment mu2(t) into the unique solutions of the respective operator equations. Following this novel approach, we have found the exact forms of mu(t) and the variance sigma2(t). Our analysis shows that the three state transition process produces less noisy transcription than a single Poisson process does, and more transition steps average out rather than propagate fluctuations of transcripts among individual cells. The noise strength phi(t) = sigma2(t)/mu(t) displays highly non-trivial dynamics during the first two to three transcription cycles. It declines steeply from the beginning until reaching the absolute minimum value, and then bounces back suddenly to a flat level close to the steady-state. Our numerical simulations further demonstrate that the cellular signals that produce the least noisy population at steady-state may not generate the least noisy population in a finite time, and suggest that measurements at steady-state may not necessarily capture most essential features of transcription noise.

Can delegated management help water utilities improve services to informal settlements?

Utility partnerships with small-scale providers (SSPs) are becoming increasingly important as utilities struggle to serve a growing population and the poor in particular. This article explores a delegated management approach as one type of partnership, in which 'master opererators' purchase bulk supplies of water and are then responsible for collecting in water payments from their customers, and introduces the case study of this approach in Nyalenda, the largest slum of Kisumu, Kenya. The authors explore why such partnership innovations in service delivery are needed and what the impact has been on the Kisumu Water and Sewerage Company and on consumers. Here 'unaccounted-for' water has decreased dramatically as both the master operators as well as the utility share an interest in preventing illegal connections. The authors also provide recommendations for the scale-up of this approach in Kisumu and the replication of the delegated management model in other cities facing similar challenges to improve servi...