Command Pattern Research Articles

Hermes-3: Multi-component plasma simulations with BOUT++

A new open source tool for fluid simulation of multi-component plasmas is presented, based on a flexible software design that is applicable to scientific simulations in a wide range of fields. Hermes-3 is built on plasma simulation framework BOUT++, consolidating earlier SD1D and Hermes models into a single code that can be configured at run-time to solve plasma models in 1D, 2D or 3D, either for transport (steady-state) or turbulent (time-evolving) problems, with an arbitrary number of ion and neutral species. We describe the improved numerical algorithms and software design that have been implemented in Hermes-3.To demonstrate the capabilities of this tool, applications relevant to the boundary of tokamak plasmas are presented: 1D simulations of diveror plasmas evolving equations for all charge states of neon and deuterium; 2D transport simulations of tokamak equilibria in single-null X-point geometry with plasma ion and neutral atom species; and simulations of the time-dependent propagation of plasma filaments (blobs).Hermes-3 is publicly available on Github under the GPL-3 open source license. The repository includes documentation and a suite of unit, integrated and convergence tests. Program summaryProgram Title: Hermes-3CPC Library link to program files:https://doi.org/10.17632/rtkvc3r743.1Developer's repository link:https://github.com/bendudson/hermes-3Licensing provisions: GPLv3Programming language: C++14Nature of problem: Simulation of dynamics and steady-state solutions of multiple ion and neutral species in magnetised plasmas using drift-reduced fluid plasma models in 1 to 3 spatial dimensions. Focused on but not restricted to the simulation of turbulence in the boundary of tokamaks.Solution method: Hermes-3 implements a system of flexible software components, that are configured at run-time and coupled by passing a state object between them (the Encapsulate State and Command patterns). Hermes-3 builds on BOUT++ [1], employing the Method of Lines with implicit and explicit time-integration methods in curvilinear coordinates on block-structured meshes, making use of libraries including SUNDIALS, PETSc and Hypre. Hermes-3 implements drift-reduced plasma fluid equations using conservative finite difference methods, and atomic processes that couple plasma and neutral fluids.

Al-insya’ Atholabi Fi Surat Al-Hujurat (Dirasah Tahliliyah Balaghiyah)

Some students face difficulties in understanding the meaning of the Quran in the form of insya thalabi with various meanings that vary based on the context of the verse, sometimes a verse with a pattern of commands but the meaning is not an order but advice, prayer or instructions etc. The purpose of this study was to determine the pattern of insya thalabi and its meaning in Surat al-Hujurat. The type of this research is library research, the data sources in this research consist of primary sources in the form of al-Qur'an al-karim surah al-hujurat and secondary sources in the form of books related to the research theme such as interpretation books, balagah and dictionaries. The research data were analyzed using Balagah descriptive analysis. The results showed that there were 34 insya thalabi in the letter al-hujurat, 16 in the form of amr, 9 in the form of nahi, two in the form of istifham, 6 in the form of nida and 1 in the form of tamanni. As for the meaning of 34 insya thalabi, it is divided into two kinds, namely the essential meaning and the meaning of balaghi. The meaning of balaghi in insya thalabi letter al-hujurat is al-tahdid, al-nuskhi, al-irsyad, al-khusi, al-tasyji', al-khabar, al-tahdid, al-taqrir, al-inkar, al-tamanni li al-wuqu'.

A geometric approach to quantifying the neuromodulatory effects of persistent inward currents on individual motor unit discharge patterns

Objective. All motor commands flow through motoneurons, which entrain control of their innervated muscle fibers, forming a motor unit (MU). Owing to the high fidelity of action potentials within MUs, their discharge profiles detail the organization of ionotropic excitatory/inhibitory as well as metabotropic neuromodulatory commands to motoneurons. Neuromodulatory inputs (e.g. norepinephrine, serotonin) enhance motoneuron excitability and facilitate persistent inward currents (PICs). PICs introduce quantifiable properties in MU discharge profiles by augmenting depolarizing currents upon activation (i.e. PIC amplification) and facilitating discharge at lower levels of excitatory input than required for recruitment (i.e. PIC prolongation). Approach. Here, we introduce a novel geometric approach to estimate neuromodulatory and inhibitory contributions to MU discharge by exploiting discharge non-linearities introduced by PIC amplification during time-varying linear tasks. In specific, we quantify the deviation from linear discharge (‘brace height’) and the rate of change in discharge (i.e. acceleration slope, attenuation slope, angle). We further characterize these metrics on a simulated motoneuron pool with known excitatory, inhibitory, and neuromodulatory inputs and on human MUs (number of MUs; Tibialis Anterior: 1448, Medial Gastrocnemius: 2100, Soleus: 1062, First Dorsal Interosseus: 2296). Main results. In the simulated motor pool, we found brace height and attenuation slope to consistently indicate changes in neuromodulation and the pattern of inhibition (excitation–inhibition coupling), respectively, whereas the paired MU analysis (ΔF) was dependent on both neuromodulation and inhibition pattern. Furthermore, we provide estimates of these metrics in human MUs and show comparable variability in ΔF and brace height measures for MUs matched across multiple trials. Significance. Spanning both datasets, we found brace height quantification to provide an intuitive method for achieving graded estimates of neuromodulatory and inhibitory drive to individual MUs. This complements common techniques and provides an avenue for decoupling changes in the level of neuromodulatory and pattern of inhibitory motor commands.

Implementation of MFCC and SVM for Voice Command Recognition as Control on Mobile Robot

The mobile robot is a system that can move according to function and task. An example is an industrial robot taking objects using a remote control system. Robots controlled using a manual remote system are generally carried out on mobile robots. Many researchers have developed manual control methods, such as image or sound-based robot control. In this study, the mobile robot was applied in an unobstructed room and controlled using voice commands. The methods used are Mel-Frequency Cepstral Coefficients (MFCC) and Support Vector Machine (SVM). MFCC is a characteristic identification of voice command patterns such as “forward”, “backward”, “left”, “right”, and “stop.” SVM is used to recognize voice command patterns based on the value of the MFCC for each pattern. The experiment has been carried out 50 times with a success rate of 96%. Overall the robot can be controlled by voice commands with good movement.

Torque/Speed Control of 3PH Synchronous Reluctance Motor Using Direct Torque Control

This paper presents an investigation of the dynamic performance of the synchronous reluctance motor (SynRM) controlled by the Direct Torque Control (DTC) technique to attain either torque or speed control. The system under study comprises synchronous reluctance motor driving a mechanical load. The inner control loop of the DTC algorithm is employed to achieve torque control through the torque hysteresis comparator in which the command torque is set externally as desired. The speed control is accomplished by adding an outer control loop comprising a speed comparator and PID controller. The controller parameters are accurately tuned to provide high transient and improved dynamic performance of the motor. The SynRM model, in the d-q synchronously rotating reference frame, and the overall components of the DTC algorithm are formulated in MATLAB/Simulink. The transient and dynamic response of the SynRM controlled by DTC is investigated when the overall system is subjected to various patterns of torque and speed commands. The results confirmed that the proposed DTC technique attained a stable, fast, and robust response for both torque and speed control loops of the controlled SynRM. Furthermore, the impact of varying the controller sampling time was explored, the outcomes revealed that as the sampling time reduces, the motor dynamic performance is significantly improved.

PRINCIPLES FOR DEVELOPMENT OF PROGRAM INTERFACES IN INDUSTRIAL INFORMATION, MEASURING, AND CONTROLLING SYSTEMS

Industrial information, measuring, and controlling systems have a program module designed to convert measurement results into data for display and control signals. A program module interconnected to other modules by program interfaces. In this case, data transformations are necessary when they are sent between modules. Object-oriented design patterns can be used when programming data transformations. When converting measurement results to objects, the Adapter design pattern can be applied. Programming the Command pattern is intended for converting objects into control signals. Data processing should be separated from their representation, storage and transmission. Functions between modules can be divided using the Model–View–Controller pattern. The use of design patterns reduces the development time and subsequent modification of software for both information, measuring, and control systems, as well as systems in other subjects of science and economics.

A cerebellar-thalamocortical pathway drives behavioral context-dependent movement initiation

SummaryExecuting learned motor behaviors often requires the transformation of sensory cues into patterns of motor commands that generate appropriately timed actions. The cerebellum and thalamus are two key areas involved in shaping cortical output and movement, but the contribution of a cerebellar-thalamocortical pathway to voluntary movement initiation remains poorly understood. Here, we investigated how an auditory “go cue” transforms thalamocortical activity patterns and how these changes relate to movement initiation. Population responses in dentate/interpositus-recipient regions of motor thalamus reflect a time-locked increase in activity immediately prior to movement initiation that is temporally uncoupled from the go cue, indicative of a fixed-latency feedforward motor timing signal. Blocking cerebellar or motor thalamic output suppresses movement initiation, while stimulation triggers movements in a behavioral context-dependent manner. Our findings show how cerebellar output, via the thalamus, shapes cortical activity patterns necessary for learned context-dependent movement initiation.

Brain-Controlled Wheelchair Review: From Wet Electrode to Dry Electrode, From Single Modal to Hybrid Modal, From Synchronous to Asynchronous

Brain-computer interface (BCI) is a novel human-computer interaction model, which does not depend on the conventional output pathway (peripheral nerve and muscle tissue). In the past three decades, it has attracted the interest of researchers and gradually become a research hotspot. As a typical BCI application, the brain-controlled wheelchair (BCW) could provide a new communicating channel with the external environment for physically disabled people. However, the main challenge of BCW is how to decode multi-degree of freedom control instruction from electroencephalogram (EEG) as soon as possible. The research progress of BCW has been developed rapidly over the past fifteen years. In this review, we investigate the BCW from multiple perspectives, include the type of signal acquisition, the pattern of commands for the control system and the working mechanism of the control system. Furthermore, we summarize the development trend of BCW based on the previous investigation, and it is mainly manifested in three aspects: from a wet electrode to dry electrode, from single-mode to multi-mode, and from synchronous control to asynchronous control. With the continuous development of BCW, we also find new functions have been introduced into BCW to increase its stability and robustness. It is believed that BCW will be able to enter the real-life from the laboratory and will be widely used in rehabilitation medicine in the future.

Empirical study of the relationship between design patterns and code smells.

Software systems are often developed in such a way that good practices in the object-oriented paradigm are not met, causing the occurrence of specific disharmonies which are sometimes called code smells. Design patterns catalogue best practices for developing object-oriented software systems. Although code smells and design patterns are widely divergent, there might be a co-occurrence relation between them. The objective of this paper is to empirically evaluate if the presence of design patterns is related to the presence of code smells at different granularity levels. We performed an empirical study using 20 design patterns and 13 code smells in ten small-size to medium-size, open source Java-based systems. We applied statistical analysis and association rules. Results confirm that classes participating in design patterns have less smell-proneness and smell frequency than classes not participating in design patterns. We also noticed that every design pattern category act in the same way in terms of smell-proneness in the subject systems. However, we observed, based on the association rules learning and the proposed validation technique, that some patterns may be associated with certain smells in some cases. For instance, Command patterns can co-occur with God Class, Blob and External Duplication smell.

Design of Virtual Chemical Experiment Platform Based on Unity3D

The problem we are trying to solve in this paper is how to determine whether the operation sequence is correct and how to achieve undo and redo when we design the virtual chemistry experiment platform in Unity3d. The approach we adopt to solve the problem is we mainly use the design idea of directed acyclic graph to solve the problem of judging operation sequence. We use command pattern and stack data structure to achieve the methods of undo and redo. By solving the above problems, we have successfully implemented the sequence of judgment and the methods of undo and redo in Unity3d. The methods implemented in this paper are not only applicable to the virtual chemistry experiment platform, but also play a role in other systems need them.

Semantics preserving SQL-to-SPARQL query translation for Nested Right and Left Outer Join

Abstract Despite the emergence of semantic web due to its high performance in managing a large amount of data through semantic filters, the relational databases are still the most used. Therefore establishing a connection between both heterogeneous systems becomes a relevant need so as to bridge the gap between them. Regarding the query mapping from relational world to semantic world (SQL-to-SPARQL), some solutions have been developed to realize this transformation but unfortunately, all existing approaches do not consider the semantic correspondence between Left/Right Outer Join command(s) and Optional pattern(s). This weakness has motivated us to investigate in this direction and suggest an efficient solution to deal with this problem by proposing, to the best of our knowledge, the first query mapping algorithm ensuring the semantic transformation of simple/nested Left/Right Outer Join command(s) in SQL queries to a simple/nested Optional pattern(s) in SPARQL equivalent ones without physical transformation of data.

Rapid visuomotor feedback gains are tuned to the task dynamics.

Adaptation to novel dynamics requires learning a motor memory, or a new pattern of predictive feedforward motor commands. Recently, we demonstrated the upregulation of rapid visuomotor feedback gains early in curl force field learning, which decrease once a predictive motor memory is learned. However, even after learning is complete, these feedback gains are higher than those observed in the null field trials. Interestingly, these upregulated feedback gains in the curl field were not observed in a constant force field. Therefore, we suggest that adaptation also involves selectively tuning the feedback sensitivity of the sensorimotor control system to the environment. Here, we test this hypothesis by measuring the rapid visuomotor feedback gains after subjects adapt to a variety of novel dynamics generated by a robotic manipulandum in three experiments. To probe the feedback gains, we measured the magnitude of the motor response to rapid shifts in the visual location of the hand during reaching. While the feedback gain magnitude remained similar over a larger than a fourfold increase in constant background load, the feedback gains scaled with increasing lateral resistance and increasing instability. The third experiment demonstrated that the feedback gains could also be independently tuned to perturbations to the left and right, depending on the lateral resistance, demonstrating the fractionation of feedback gains to environmental dynamics. Our results show that the sensorimotor control system regulates the gain of the feedback system as part of the adaptation process to novel dynamics, appropriately tuning them to the environment.NEW & NOTEWORTHY Here, we test whether rapid visuomotor feedback responses are selectively tuned to the task dynamics. The responses do not exhibit gain scaling, but they do vary with the level and stability of task dynamics. Moreover, these feedback gains are independently tuned to perturbations to the left and right, depending on these dynamics. Our results demonstrate that the sensorimotor control system regulates the feedback gain as part of the adaptation process, tuning them appropriately to the environment.

Does Design Pattern Support Easy Change Impact Analysis? - Focusing on the Command Pattern

Design patterns, a solution for the specific context and the problem, give benefits to us what a good design creates if we adequately use them in accordance with their purposes and principles. However, if we do not use them with inadequate purposes, using design patterns can be causes of increasing costs and decreasing maintainability and system performance. An industrial robot completes its given task through a series of hardware device’s primitive movements, controlled by an application using the APIs provided by specific hardware vendors. However, required movements of a robot change frequently because the given task changes often. This requires changes on hardware devices. As a consequence of this, APIs, controlling the hardware device change, and we also should modify the corresponding application. Therefore, an industrial robot software application should be designed such that it can easily trace hardware device’s change impacts on the application as well as it defines ordered composite primitive movements for completing the required task. This paper implements parts of an application that use hardware dependent APIs by using the command pattern and validates whether it support each change impact analysis.

Re-engineering SAM or Changing the Engine in the Train While it is Running

In the last few years at Fermilab we re-architect-ed our SAM1[1] family of data catalog and file transfer tools - including major changes - while continuing to transfer over 1 Pb/month of data to multiple existing experiments and bring new experiments on board. This work was done with less than 3 FTE-years of effort, and the changes made include major ones, such as changing interprocess communication protocols, migrating database back-ends, removing and replacing major components, and supporting new file delivery methods. This paper will summarize the approaches we have used to do this, including using design patterns like the Facade, Adapter, and Command patterns, and assisting experiments one at a time with client migration. This process has allowed us to modernize our infrastructure with reasonable costs in both calendar time and developer effort, while continuing to provide the operating service to our customers with minimal interruptions.

Pilots 2.0: DIRAC pilots for all the skies

In the last few years, new types of computing infrastructures, such as IAAS (Infrastructure as a Service) and IAAC (Infrastructure as a Client), gained popularity. New resources may come as part of pledged resources, while others are opportunistic. Most of these new infrastructures are based on virtualization techniques. Meanwhile, some concepts, such as distributed queues, lost appeal, while still supporting a vast amount of resources. Virtual Organizations are therefore facing heterogeneity of the available resources and the use of an Interware software like DIRAC to hide the diversity of underlying resources has become essential. The DIRAC WMS is based on the concept of pilot jobs that was introduced back in 2004. A pilot is what creates the possibility to run jobs on a worker node. Within DIRAC, we developed a new generation of pilot jobs, that we dubbed Pilots 2.0. Pilots 2.0 are not tied to a specific infrastructure; rather they are generic, fully configurable and extendible pilots. A Pilot 2.0 can be sent, as a script to be run, or it can be fetched from a remote location. A pilot 2.0 can run on every computing resource, e.g.: on CREAM Computing elements, on DIRAC Computing elements, on Virtual Machines as part of the contextualization script, or IAAC resources, provided that these machines are properly configured, hiding all the details of the Worker Nodes (WNs) infrastructure. Pilots 2.0 can be generated server and client side. Pilots 2.0 are the “pilots to fly in all the skies”, aiming at easy use of computing power, in whatever form it is presented. Another aim is the unification and simplification of the monitoring infrastructure for all kinds of computing resources, by using pilots as a network of distributed sensors coordinated by a central resource monitoring system. Pilots 2.0 have been developed using the command pattern. VOs using DIRAC can tune pilots 2.0 as they need, and extend or replace each and every pilot command in an easy way. In this paper we describe how Pilots 2.0 work with distributed and heterogeneous resources providing the necessary abstraction to deal with different kind of computing resources.

Human-Machine Interface for the Control of Multi-Function Systems Based on Electrocutaneous Menu: Application to Multi-Grasp Prosthetic Hands.

Modern assistive devices are very sophisticated systems with multiple degrees of freedom. However, an effective and user-friendly control of these systems is still an open problem since conventional human-machine interfaces (HMI) cannot easily accommodate the system’s complexity. In HMIs, the user is responsible for generating unique patterns of command signals directly triggering the device functions. This approach can be difficult to implement when there are many functions (necessitating many command patterns) and/or the user has a considerable impairment (limited number of available signal sources). In this study, we propose a novel concept for a general-purpose HMI where the controller and the user communicate bidirectionally to select the desired function. The system first presents possible choices to the user via electro-tactile stimulation; the user then acknowledges the desired choice by generating a single command signal. Therefore, the proposed approach simplifies the user communication interface (one signal to generate), decoding (one signal to recognize), and allows selecting from a number of options. To demonstrate the new concept the method was used in one particular application, namely, to implement the control of all the relevant functions in a state of the art commercial prosthetic hand without using any myoelectric channels. We performed experiments in healthy subjects and with one amputee to test the feasibility of the novel approach. The results showed that the performance of the novel HMI concept was comparable or, for some outcome measures, better than the classic myoelectric interfaces. The presented approach has a general applicability and the obtained results point out that it could be used to operate various assistive systems (e.g., prosthesis vs. wheelchair), or it could be integrated into other control schemes (e.g., myoelectric control, brain-machine interfaces) in order to improve the usability of existing low-bandwidth HMIs.

Application Study on an Extended Design Pattern

Proposed a extend design pattern, which oriented distributed environment. Design framework in which import some components, such as command bus, command executor. Design the structure class diagram of the pattern. Expatiated components’ specific function, and analyses the command execution process in the pattern. Based on the pattern, when developers design command classes, there is no need to consider how to sequence the command object and send it to server, and they don’t worry about receiving data from server and anti-serialize from the received data. Conclude that developers can use command pattern in a network transparent manner in accordance with the original way.

New Damped-Jerk trajectory for vibration reduction

This paper derives a jerk-shaped profile to address the vibration reduction of underdamped flexible dynamics of motion system. The jerk-limited profile is a widespread smooth command pattern used by modern motion systems. The ability of the jerk-limited profile to cancel the residual vibration of an undamped flexible mode is clearly explained using an equivalent continuous filter representation and the input shaping formalism. This motivates the design of a new jerk-shaped profile, named Damped-Jerk profile, to extend the previous result to the more common case of underdamped systems. Both simulations and experimental results demonstrate the effectiveness of the proposed Damped-Jerk profile to reduce damped vibration.

Ushering the Cactvs Toolkit into the Python Age (without breaking the legacy)

The Cactvs Chemoinformatics Toolkit is probably the most powerful general-purpose chemical information processing toolkit on the market. Since its inception about twenty years ago, its main language for rapid script development has been Tcl – at that time a language at the forefront of lazily-typed rapid prototyping and interface programming language design. While Tcl is still actively maintained, and does provide features not matched by many of the nowadays more popular competitors – most notably impressive multi-threading capabilities, which are fully accessible from within the toolkit – history has passed on. Tcl has undeniably fallen out of the public eye, and there is an understandable reluctance by users to learn new languages which are effectively only used by one of their tools. This problem has finally been addressed. The Cactvs toolkit is now available with Python as a second alternative (or parallel) interface language. The new interface closely follows the established Tcl command patterns to support easy migration by experienced users, while still providing true “pythonesque” constructs. Since significant functionality of the toolkit is implemented as external Tcl script function snippets, and future enhancements will probably preferably be coded in Python without providing also a Tcl port, providing automatic and fully transparent access to language-mismatched components has been an important and rather peculiar design goal. Examples of the new toolkit scripting capabilities shall be presented, as well as a documentation of the challenges involved in the design of a parallel multi-language interface to a large software system.

Command Pattern Classification Model Based on Experimental Data Mining

This paper builds sample analysis data sets through the analysis of specific commands behavior in command behavior experiment, and selects typical commanders as reference sample, proposes a command pattern classification model based on k-means clustering algorithms. The command model calculation is simple, easy for computer implementation, and is of great significance in understanding and mastering specific commanders characteristics, and application to practical operations and training.