Use Of Threads Research Articles

Effect of Size and Type of Skirted Surface on Breaking Load of Sewing Threads in Loops Under Different Stretching Conditions

The results of the study of the dependence of breaking load of threads in a loop under different stretching conditions are reported. It is shown that the size and type of skirted surfaces markedly affect the breaking load of threads. Threads from para-aramid staple fibres suffer the maximum breaking load loss. In the case of asymmetric stretching, which best takes account of the conditions of processing and use of threads, the breaking load of the latter is substantially lower compared to the results obtained by traditional procedure.

WRF 물리 과정의 GP-GPU 계산을 위한 CUDA Fortran 프로그램 구현

We parallelized WRF major physics routines for Nvidia GP-GPUs with CUDA Fortran. GP-GPUs are originally designed for graphic processing, but show high performance with low electricity for calculating numerical models. In the CUDA environment, a data domain is allocated into thread blocks and threads in each thread block are computing in parallel. We parallelized the WRF program to use of thread blocks efficiently. We validated the GP-GPU program with the original CPU program, and the WRF model using GP-GPUs shows efficient speedup.

Using the Parallelism Viewpoint to Optimize the Use of Threads in Parallelism-intensive Software Systems

The use of multithreading can enhance the performance of a software system. However, its excessive use can degrade the performance. For example, a thread-per-job approach might lead to a large amount of threads with increased associated overheads. In this paper we explore the use of the Parallelism Viewpoint to support one possible strategy to reduce the number of threads, namely finding candidate threads that can be replaced by thread pooling. Thread pooling reduces the large number of threads by reusing threads from an existing pool. As an example we analyze the threads of a precision critical parallelism-intensive electron microscope software system. Results show that the viewpoint provides a profound insight into the threading structure of the system, which helps in reducing the number of threads in a cost-effective way. And, the total time gain along with such reduction is encouraging. viewpoint to identify potential threads for pooling. The motivation behind using the Parallelism Viewpoint for thread analysis is two-fold. First, architecture level analysis is a proven cost-effective approach that provides an opportunity to find and fix issues up-front in the system development (3). Second, the Parallelism Viewpoint provides an in-depth understanding, not only about the thread behaviour but also about associated concerns and stakeholders. Such understanding is essential while making any change in the thread model. In this paper, we describe with the help of an industrial case how the Parallelism Viewpoint can be used to identify threads that are suitable to be replaced with a thread pool. The case is a large and complex parallelism-intensive software system used for electron microscopes. It is a client- server distributed system whose design follows a component-based architecture. It runs on the Microsoft Windows XP operating system. Because of the heterogeneous nature of the machine, its devices come from multiple domains such as electronics, mechanics and physics. The software is responsible for data acquisition and control of these devices. It has a large code base with multi- million lines of code and employs several hundred threads to perform various microscopy functions. We believe that the performance of the software can be enhanced by reducing the number of threads. This can be achieved by replacing them with a small sized thread pool, provided that accurate threads are selected for such replacement. The remainder of this paper is organized as follows. In the next section we briefly describe the building blocks of Parallelism Viewpoint. We outline the analysis approach in section III and apply it on an industrial case in section IV. Section V contains related work, and finally in section VI we draw conclusions and state our future work.

Efficient parallelization for AMR MHD multiphysics calculations; implementation in AstroBEAR

Current adaptive mesh refinement (AMR) simulations require algorithms that are highly parallelized and manage memory efficiently. As compute engines grow larger, AMR simulations will require algorithms that achieve new levels of efficient parallelization and memory management. We have attempted to employ new techniques to achieve both of these goals. Patch or grid based AMR often employs ghost cells to decouple the hyperbolic advances of each grid on a given refinement level. This decoupling allows each grid to be advanced independently. In AstroBEAR we utilize this independence by threading the grid advances on each level with preference going to the finer level grids. This allows for global load balancing instead of level by level load balancing and allows for greater parallelization across both physical space and AMR level. Threading of level advances can also improve performance by interleaving communication with computation, especially in deep simulations with many levels of refinement. While we see improvements of up to 30% on deep simulations run on a few cores, the speedup is typically more modest (5–20%) for larger scale simulations. To improve memory management we have employed a distributed tree algorithm that requires processors to only store and communicate local sections of the AMR tree structure with neighboring processors. Using this distributed approach we are able to get reasonable scaling efficiency (>80%) out to 12288 cores and up to 8 levels of AMR – independent of the use of threading.

Finding people and their utterances in social media

At the beginning of the twenty-first century, the web entered a phase of explosive growth. Since then, a multitude of platforms has become available for users to publish information, communicate with others, connect to like-minded individuals, and share anything that they want to share. These platforms are commonly known as social media. Social media enables many-to-many communication: many people can create content, which in turn can be read by many others. To make interesting content findable for many people, machines need to be able to identify the "right" pieces of content or the "appropriate" content creators. That is, we need ways to intelligently access information in social media. The main motivation for the research in my thesis is that we want to enable intelligent access to, and analysis of, the information contained in social media. To this end, we must determine the topical relevance of social media documents, while countering the specific challenges posed by their noisy and creative nature. We identify two entry points for accessing information in social media: (i) the people creating the social media and (ii) their individual utterances (e.g., blog posts, tweets). These entry points act as a doorway to the information in social media. The aim of the thesis is to improve searching for people and their utterances in social media, thereby offering intelligent access to the information it contains. In the thesis we explore ways to improve retrieval effectiveness, for both people and their utterances, in five research chapters. We start with an extensive analysis of the query logs of a people search engine and show that users are mainly interested in finding social media profiles of people for whom they search. We continue with our focus on searching for people in the second chapter, but adopt a more technical perspective. We use blog posts as representation of bloggers' interests and show that for blogger finding a combination of two models, one based on individual blog posts and one on aggregated blogger models, is both effective and efficient. In the remaining three chapters we move away from finding people and focus on individual utterances. Specifically, we look at blog post retrieval in two chapters and email retrieval in mailing lists in the last chapter. For blog post retrieval we explore the use of indicators obtained from a credibility framework. We propose ways of estimating these indicators and rerank an initial list of blog posts based on these (combined) indicator scores. We find that incorporating these indicators leads to improvements and our analysis determines indicators that are most influential. The second chapter on blog post retrieval and the chapter on email search both use a notion of "context" to help improve retrieval effectiveness. For blog post retrieval we observe that much of what is written in blog posts is based on things happening the bloggers' environments. To use this observation we propose a generative retrieval model that uses information from a set of external sources. We test our model using a news collection, Wikipedia, and a web collection as external sources. We find that our model is capable of improving retrieval performance on most topics and that the per-topic collection importance is a very useful component of the model. Finally, the last research chapter uses the direct context of emails to refine queries; we explore the use of threads, the entire mailing list, and the pages from within the same community as sources for query expansion terms. Besides that, we also incorporate the previously mentioned credibility-inspired indicators in this setting. We find that context helps in improving retrieval performance, as do the credibilityinspired indicators. Concluding, my thesis provides new insights into search behavior in social media and shows that a diverse set of methods can help improve retrieval effectiveness for multiple information access tasks within social media. Available online at http://wouter.weerkamp.com/.

An inexpensive thread-based system for simple and rapid blood grouping

This study investigates the use of thread as a flexible and low-cost substrate for the rapid grouping of blood. The use of a capillary substrate such as thread for blood grouping utilises the sensitivity of the flow resistance of large particles in narrow capillary channels to separate agglutinated red blood cells (RBCs) from plasma. Large and discrete particles formed in a continuous liquid phase do not provide capillary wicking driving force and fall behind the capillary wicking front, leading to their separation from the wicking liquid. The capillary substrate therefore provides a very promising but different mechanism for the separation of the agglutinated RBCs and the blood serum phase compared to most existing blood grouping methods. The principle of chromatographic separation is also exploited in this study via the use of suitable dyes to enhance the visual detection of the agglutinated RBCs and the serum phase; surprising and encouraging outcomes are obtained. Using a thread-based device, the ABO and Rh groups can be successfully determined with only 2μL of whole blood from a pricked finger tip within 1min and without pre-treatment of the blood sample. It is hoped that a new, inexpensive, rapid and simple method may provide an easy-to-use blood grouping platform well suited to those in developing or remote regions of the world.

Thread as a Matrix for Biomedical Assays

This paper describes the use of thread as a matrix for the fabrication of diagnostic assay systems. The kinds of thread used for this study are inexpensive, broadly available, and lightweight; some of them are already familiar materials in healthcare. Fluids wick along these threads by capillary action; no external power source is necessary for pumping. This paper demonstrates three designs for diagnostic assays that use different characteristics of the thread. The first two designs-the "woven array" and the "branching design"-take advantage of the ease with which thread can be woven on a loom to generate fluidic pathways that enable multiple assays to be performed in parallel. The third design-the "sewn array"-takes advantage of the ease with which thread can be sewn through a hydrophobic polymer sheet to incorporate assays into bandages, diapers and similar systems. These designs lead to microfluidic devices that may be useful in performing simple colorimetric assays that require qualitative results. We demonstrate the function of thread-based microfluidic devices in the context of five different colorimetric assays: detection of ketones, nitrite, protein, and glucose in artificial urine, and detection of alkaline phosphatase in artificial plasma.

Browsing Video Along Multiple Threads

This paper describes a novel method for browsing a large video collection. It links various forms of related video fragments together as threads. These threads are based on query results, the timeline as well as visual and semantic similarity. We design two interfaces which use threads as the basis for browsing. One interface shows a minimal set of threads, and the other as many as fit on the screen. To evaluate both interfaces we perform a regular user study, a study based on user simulation, and we participated in the interactive video retrieval task of the TRECVID benchmark. The results indicate that the use of threads in interactive video retrieval is beneficial. Furthermore, we found that in general the query result and the timeline are the most important threads, but having several additional threads improves the performance as it encourages people to explore new dimensions.

Interactional coherence in asynchronous learning networks: A rhetorical approach

Numerous studies have affirmed the value of asynchronous online communication as a learning resource. Several investigations, however, have indicated that discussions in asynchronous environments are often neither interactive nor coherent. The research reported sought to develop an enhanced understanding of interactional coherence, argumentation, and topic drift in asynchronous learning environments. Rhetorical structure theory (RST) was used to analyze and assess the coherence of several asynchronous discussions. Findings include that asynchronous discussions take the form of dynamic rhetorical structures which are continuously redefined as new messages are added to a thread, that argumentation may be more prevalent in some discussions than others, that topic drift does not seem to occur as a matter of chance, but rather topics are manipulated to suit the individual preferences of the participants, and that the use of threading differs considerably from one discussion group to another. By demonstrating the applicability of RST, argumentative analysis, and topic drift analysis to asynchronous discussion, this research provides a framework and a terminology for fine-grained analysis of interactional coherence. By showing the applicability of RST to asynchronous discussion, this study has offered evidence that essay assessment technology could be developed for evaluating the quality of online discussions. The development of rhetorical networks as a graph theory for representing the semantics of asynchronous interaction could lead to a richer knowledge representation technology for inter-agent collaboration.

Structure determination of a new protein from backbone‐centered NMR data and NMR‐assisted structure prediction

Targeting of proteins for structure determination in structural genomic programs often includes the use of threading and fold recognition methods to exclude proteins belonging to well-populated fold families, but such methods can still fail to recognize preexisting folds. The authors illustrate here a method in which limited amounts of structural data are used to improve an initial homology search and the data are subsequently used to produce a structure by data-constrained refinement of an identified structural template. The data used are primarily NMR-based residual dipolar couplings, but they also include additional chemical shift and backbone-nuclear Overhauser effect data. Using this methodology, a backbone structure was efficiently produced for a 10 kDa protein (PF1455) from Pyrococcus furiosus. Its relationship to existing structures and its probable function are discussed.

Dual-level parallelism for high-order CFD methods

A hybrid two-level parallel paradigm with MPI/OpenMP is presented in the context of high-order methods and implemented in the spectral/ hp element framework to take advantage of the hierarchical structures arising from deterministic and stochastic CFD problems. We take a coarse grain approach to OpenMP shared-memory parallelization and employ a workload-splitting scheme that reduces the OpenMP synchronizations to the minimum. The hybrid algorithm shows good scalability with respect to both the problem size and the number of processors for a fixed problem size. For the same number of processors, the hybrid model with 2 OpenMP threads per MPI process is observed to perform better than pure MPI and pure OpenMP on the SGI Origin 2000 and the Intel IA64 Cluster, while the pure MPI model performs the best on the IBM SP3 and on the Compaq Alpha Cluster. A key new result is that the use of threads facilitates effectively p-refinement, which is crucial to adaptive discretization using high-order methods.

Three-dimensional analysis of endosseous palatal implants and bones after vertical, horizontal, and diagonal force application.

The effects of bite and orthodontic forces exerted on endosseous palatal implants are not completely understood. This applies especially to the biomechanical properties inherent in the different implant geometries and resulting bone remodelling reactions on the one hand, and to the influence on the direction and magnitude of the applied forces on the other. The results of this study should help in the selection of implants for clinical use. Three types of endosseous implants (all 9 mm in length and 3.3 mm in diameter, made of titanium) were used for this investigation. Type 1 was a simple, cylinder-shaped implant; type 2 a cylinder-shaped implant with a superperiosteal step; and type 3 a cylinder-shaped implant, subperiosteally threaded, with a superperiosteal step. The load on the implant was investigated under three conditions of bite and orthodontic forces from 0.01 to 100 N (vertically, horizontally, and diagonally). The study results were calculated by means of a finite element (FE) method. Vertical loading caused bone deformation of more than 600 microeps at the simple implant. The largest deformations at this load were found in the trabecular bone with all three implant geometries. However, trabecular bone deformation was reduced by a superperiosteal step. Horizontal loading of the implants shifted the deformation from the trabecular to the cortical bone. Furthermore, a large deformation was measured at the transition from cortical to trabecular bone. The smallest deformations (less than 300 microeps) were found for implants with a superperiosteal step and diagonal loading (type 2). The use of threads provided no improvement in loading capacity. All implant types investigated showed good biomechanical properties. However, endosseous implants with a superperiosteal step had the best biomechanical properties under low loads. Thus, the trend should be to optimize the design of implants by producing small implants with additional anchorage on the bone surface.

Following the thread in computer conferences

Computer conferencing systems allow students to discuss their ideas and learn from each other. However, the asynchronous nature of these discussions can result in large and complex collections of messages. Threading facilities help students to cope with this by structuring their discussions into parallel ‘conversations’. This paper discusses an investigation of students’ use of threading in two different conferencing systems. The context for the study was a small-group collaborative assignment in an Open University course. Conference transcripts were studied, and ‘message maps’ were created, in order to investigate the threading links made by students, in relation to the semantic links between the messages. The results show that the way in which threads are represented in a conferencing system can have a significant effect on how students use the system, and on the character of the resulting discussions.

Dynamic instrumentation of threaded applications

The use of threads is becoming commonplace in both sequential and parallel programs. This paper describes our design and initial experience with non-trace based performance instrumentation techniques for threaded programs. Our goal is to provide detailed performance data while maintaining control of instrumentation costs. We have extended Paradyn's dynamic instrumentation (which can instrument programs without recompiling or relinking) to handle threaded programs.Controlling instrumentation costs means efficient instrumentation code and avoiding locks in the instrumentation. Our design is based on low contention data structures. To associate performance data with individual threads, we have all threads share the same instrumentation code and assign each thread with its own private copy of performance counters or timers. The asynchrony in a threaded program poses a major challenge to dynamic instrumentation. To implement time-based metrics on a per-thread basis, we need to instrument thread context switches, which can cause instrumentation code to interleave. Interleaved instrumentation can not only corrupt performance data, but can also cause a scenario we call self-deadlock where an instrumentation code deadlocks a thread. We introduce thread-conscious locks to avoid self-deadlock, and per-thread virtual CPU timers to reduce the chance of interleaved instrumentation accessing the same performance counter or timer, and to reduce the number of expensive timer calls at thread context switches.Our initial implementation is on SPARC Solaris 2.5 and 2.6 including multiprocessor Sun UltraSPARC Enterprise machines. We tested our tool on large multithreaded applications, including the Java Virtual Machine (JVM). We show how our new techniques helped us to speed up a Java graphics native method by 42% and consequently increase by 24% the amount of work that can be done in unit time in a game applet.

Energy-based de novo protein folding by conformational space annealing and an off-lattice united-residue force field: application to the 10-55 fragment of staphylococcal protein A and to apo calbindin D9K.

The conformational space annealing (CSA) method for global optimization has been applied to the 10-55 fragment of the B-domain of staphylococcal protein A (protein A) and to a 75-residue protein, apo calbindin D9K (PDB ID code), by using the UNRES off-lattice united-residue force field. Although the potential was not calibrated with these two proteins, the native-like structures were found among the low-energy conformations, without the use of threading or secondary-structure predictions. This is because the CSA method can find many distinct families of low-energy conformations. Starting from random conformations, the CSA method found that there are two families of low-energy conformations for each of the two proteins, the native-like fold and its mirror image. The CSA method converged to the same low-energy folds in all cases studied, as opposed to other optimization methods. It appears that the CSA method with the UNRES force field, which is based on the thermodynamic hypothesis, can be used in prediction of protein structures in real time.

Evaluation of Java thread performance on two different multithreaded kernels

Modern programming languages and operating systems encourage the use of threads to exploit concurrency and simplify program structure. An integral and important part of the Java language is its multithreading capability. Despite the portability of Java threads across almost all platforms, the performance of Java threads varies according to the multithreading support of the underlying operating system and the way Java Virtual Machine maps Java threads to the native system threads. In this paper, a well-known compute-intensive benchmark, the EP benchmark, was used to examine various performance issues involved in the execution of threads on two different multithreaded platforms: Windows NT and Solaris. Experiments were carried out to investigate thread creation and computation behavior under different system loads, and to explore execution features under certain extreme situations such as the concurrent execution of very large number of Java threads. Some of the experimental results obtained from threads were compared with a similar implementation using processes. These results show that the performance of Java threads differs depending on the various mechanisms used to map Java threads to native system threads, as well as on the scheduling policies for these native threads. Thus, this paper provides important insights into the behavior and performance of Java threads on these two platforms, and highlights the pitfalls that may be encountered when developing multithreaded Java programs.

Granularity of modules in object-based concurrent systems

Granularity of modules in object-based concurrent systems

Experimental Study of Ice Flow Around a Bump: Comparison with Theory

Flow of ice over a pair of streamlined bumps was studied in a laboratory apparatus. Experimental conditions were similar to those under a glacier about 100 m thick with a shear stress of 0.1 MPa. Temperatures in the ice and bed were monitored with thermistors. Cumulative deformation was determined with the use of threads frozen into the ice. The threads were initially vertical, but were deformed during the experiment.About 75 % of the accommodation of the bumps was by plastic deformation, and 25 % was by pressure melting. Much of the heat for melting came from the boundaries of the apparatus so the melt water formed did not refreeze in the lee of the bumps.The cumulative deformation in the ice is compared with a theoretical prediction of Lliboutry and Ritz (1978) for flow over hemispherical bumps. The principal difference between theory and experiment, aside from that in bump geometry, is that the theory assumes a frictionless boundary between the bed and the ice, whereas in the experiment small-scale roughness elements result in drag. Because the theory ignores this drag, it overestimates the velocity immediately above the bump. The experimental deformation profiles are consistent with those predicted for a non-linear rheology, but not with those predicted for a linear rheology.

Sewing Needle Temperature

The effect of various sewing conditions and needle characteristics on the temperature observed during high speed sewing has been studied. The maximum needle temperatures were determined by means of infrared (ir) flux measurements. A complete statistical experiment was used to show the effect of sewing speed, the use of thread as compared to no thread in testing, thread size, and needle diameter on the needle temperature. The temperature was found to increase with speed at a rate of about 0.08°F/rpm. The use of thread was found to decrease the observed temperatures by as much as 200°F and there was a significant thread-speed interaction. Thread size and needle diameter were not found to be significant. It was found possible to reduce the needle temperature by 10-15% by using a cyclic type of operation with short periods of sewing followed by short periods of idle time. The use of thread or cloth lubricants were found to have very little effect. The use of forced air cooling was found to be very effective in lowering the needle temperatures with reductions of 150-200°F being easily obtained. It is concluded that the application of all the factors shown to reduce needle temperatures could reduce the temperature of a chrome-plated needle sewing at 4000 rpm from 700°F to below 300°F for a Kooltorr® needle sewing at 3000 rpm on a machine equipped with an air cooling pump.

The Convergent Development of Orb-webs in Cribellate and Ecribellate Spiders

Orb-webs are highly developed and can be understood as the best technical solution of the problem how to place capture-threads in the most efficient and economical way. They are built by cribellate and ecribellate spiders. Phylogenetical relations between some families of Cribellate and Ecribellate cannot be ignored, but for some important reasons it is difficult to imagine that on the level of orb-weaving cribellate spiders became ecribellate by reducing the cribellum. Thus, these specialised webs must have developed on both sides independently and are the result of a convergent evolution. Steps leading from primitive use of threads for capturing insects to the typical and latter modified orb-webs of Cribellate and Ecribellate can be discerned.