SMP Systems Research Articles

Smart shape memory polymers and their significance in biomedical applications: A review

AbstractShape‐memory polymers (SMP) are materials responsive to stimuli, which will be modified to their initial form on the occurrence of an appropriate input. SMPs have been a class of impulsively valuable material in the last few decades. Because of their numerous, adaptable uses across a wide range, “wise” materials (SMPs) have attracted intense interest in the advanced material fields. Besides others, they need a substantial part of the area of the medical field. SMPs provide flexibility for promoting keyhole surgery, which offers stable strength, imposes stabilization forces, rinse therapeutic agents, and are degradable. Basic research on proposed SMP systems for medicine emphasizes biocompatibility, tolerability, disinfection, and non‐toxicity. This article mentions an overview of the latest advancements in the applications of SMP been reported. The article aims to incorporate all the possible applications of SMP, making it a versatile material that juxtaposes it with other advanced materials. The significance of SMP in the biomedical field, drug development, cardio‐vascular diseases, tissue engineering, wound dressing, surgical sutures, and many other applications has been highlighted. Another section dedicated to the antimicrobial abilities of SMP has been discussed. The last section is devoted to the conclusion and future developments in the respective area. Thus, this review focuses on many biomedicine areas and tube, medical science, and neuronic applications regarding the development and ability of SMPs to boost the quality of services in these fields.

4D Printing of Multicomponent Shape-Memory Polymer Formulations

Four-dimensional (4D) printing technology, as a next-generation additive manufacturing method, enables printed objects to further change their shapes, functionalities, or properties upon exposure to external stimuli. The 4D printing of programmable and deformable materials such as thermo-responsive shape-memory polymers (trSMPs), which possess the ability to change shape by exposure to heat, has attracted particular interest in recent years. Three-dimensional objects based on SMPs have been proposed for various potential applications in different fields, including soft robotics, smart actuators, biomedical and electronics. To enable the manufacturing of complex multifunctional 3D objects, SMPs are often coupled with other functional polymers or fillers during or before the 3D printing process. This review highlights the 4D printing of state-of-the-art multi-component SMP formulations. Commonly used 4D printing technologies such as material extrusion techniques including fused filament fabrication (FFF) and direct ink writing (DIW), as well as vat photopolymerization techniques such as stereolithography (SLA), digital light processing (DLP), and multi-photon polymerization (MPP), are discussed. Different multicomponent SMP systems, their actuation methods, and potential applications of the 3D printed objects are reviewed. Finally, current challenges and prospects for 4D printing technology are summarized.

Development of functional fault-tolerant system

Before you begin to develop a fault-tolerant system, you should specify the system requirements. Besides high fault tolerance and performance, the computing system shall be highly available. Such systems include NUMA systems with non-uniform memory access, SMP systems with symmetrical multiprocessing and MPP mass-parallel systems. The ultimate choice of architecture largely depends on whether maximum performance, scalability, or fault tolerance and availability are needed.

Clay/chitosan biocomposite systems as novel green carriers for covalent immobilization of food enzymes

In this work, innovative green composite systems, based on high amounts of montmorrilonite (MMT) and low amounts of chitosan in different relative ratios (70:30, 75:25, 80:20, % w/w), were proposed as potential alternatives to the free nanoclay particles, commonly used as carriers for enzymes covalent immobilization. In details, two different MMT were selected, i.e. SMP (a high purity unmodified MMT) and Optigel (OPT, an activated food-grade MMT). The chitosan was used both to make the clays appropriate supports for the enzymes covalent binding, and to maintain the clay particles together in a unique structure, acting as a binder. The mechanical, thermal, and chemical properties of the obtained composite systems were studied. Moreover, the catalytic properties of a protease covalently immobilized on these carriers were investigated in a model wine-like medium toward a synthetic substrate. OPT based composite systems presented higher σmax and Young modulus values with respect to the SMP based ones, due to OPT better distribution and interaction with the chitosan. Irrespective of nanoclays amount, SMP and OPT composite systems appeared suitable carriers for the covalent immobilization of protease, with an immobilization yield of 18% and 14–17%, respectively. The highest product release velocity was detected when the protease was immobilized on OPT carriers (Vmax 10.49-10.74 mIUmg−1IP), and the greatest apparent affinity when it was linked to SMP composite systems (Ka 2.19–3.10min−1μM).

Carbon fiber reinforced shape memory epoxy composites with superior mechanical performances

For the shape memory polymers' (SMPs) applications in demanding, high performance scenarios are usually limited by their poor mechanical performances during shape transformation. In this work, shape memory epoxy composites (SMEPCs) with superior mechanical properties are fabricated by adding various short and continuous carbon fibers (CFs) into neat shape memory epoxies (SMEPs) matrix. The resultant SMEPC's storage modulus (E’) at room temperature is as high as 37 GPa, and the maximum recovery force exceeds 4.4 GPa, with good shape memory capabilities. These properties are at least an order of magnitude higher than those in existing typical SMP systems. The excellent mechanical properties of the fibers and their ability to retard crack propagation in the matrix are believed to play an important role in achieving high moduli below and above the shape-memory triggering temperature. The potential applications of such SMEPCs are demonstrated with wind blades. Experimental results and numerical models regarding air flow velocity variation as initiated by shape change in the blades indicate that our SMEPCs can sustain continuous stable mechanical state and provide variable wind speeds. These CF reinforced SMEPCs can be employed as smart structural materials to automatically switch shapes in response to the change in environment, such as those seen in aero foils and energy harvesters.

Revisiting locality-awareness in view of dynamically changing topologies

Abstract As a general rule, when writing parallel applications according to the MPI standard, the programmer does not need to worry about the underlying hardware topology. This is because the MPI standard intentionally hides the actual hardware topology from the application programmer for the seizure of portability, while at the same time burdening the MPI implementation to handle hardware-related peculiarities as optimal as possible. So, for instance, with the emergence of SMP systems, locality-awareness in terms of the recognition of accelerated node-internal communication found its way into all major MPI libraries in the early 2000s. However, the actually implemented degree of such a locality-awareness can vary: From the simple usage of point-to-point communication over shared-memory, via the smart adaptation of collective communication patterns, through to the exploitation of direct accessible address spaces for one-sided communication. Until now, all these locality-related optimizations basically assume a static hierarchical topology in the course of a parallel program. In contrast, this article strives for a discussion of how dynamically changing topologies, as they may result from process migrations, can be considered during runtime for locality-awareness. In doing so, the article focuses on collective communication, but also discusses the challenges for point-to-point and one-sided communication.

Flexible simulations of complex networks in OpenStack clouds

This paper describes a flexible software architecture aimed at performing simulations of complex networks on cloud computing environment based on OpenStack. The kernel of the architecture consists of ComplexSim, a C-based software simulator of complex networks composed of two different layers: the Parallel Simulation Kernel is devoted to manage event-driven simulations on SMP systems through a set of API calls useful to schedule tasks and events; on the other hand, API of the Complex Network Data & Runtime is used to define the complex network in terms of the graph of entities and related user-defined attributes, as well as the runtime behaviour. Two additional components provide the necessary automation to configure, deploy and execute a set of simulations in OpenStack clouds: the Cs-Generator allows to generate any set of user-defined directives, as well as directives for the engine; Cs-CloudRuntime is the component devoted to run the user-defined set of simulations in an OpenStack cloud, i.e. VMs preparation, deployment and execution, as well as collection of results.

Flexible simulations of complex networks in OpenStack clouds

This paper describes a flexible software architecture aimed at performing simulations of complex networks on cloud computing environment based on OpenStack. The kernel of the architecture consists of ComplexSim, a C-based software simulator of complex networks composed of two different layers: the Parallel Simulation Kernel is devoted to manage event-driven simulations on SMP systems through a set of API calls useful to schedule tasks and events; on the other hand, API of the Complex Network Data & Runtime is used to define the complex network in terms of the graph of entities and related user-defined attributes, as well as the runtime behaviour. Two additional components provide the necessary automation to configure, deploy and execute a set of simulations in OpenStack clouds: the Cs-Generator allows to generate any set of user-defined directives, as well as directives for the engine; Cs-CloudRuntime is the component devoted to run the user-defined set of simulations in an OpenStack cloud, i.e. VMs preparation, deployment and execution, as well as collection of results.

Static analysis of the hull plate using the finite element method

This paper aims at presenting the static analysis for two levels of a container ship's construction as follows: the first level is at the girder / hull plate and the second level is conducted at the entire strength hull of the vessel. This article will describe the work for the static analysis of a hull plate. We shall use the software package ANSYS Mechanical 14.5. The program is run on a computer with four Intel Xeon X5260 CPU processors at 3.33 GHz, 32 GB memory installed. In terms of software, the shared memory parallel version of ANSYS refers to running ANSYS across multiple cores on a SMP system. The distributed memory parallel version of ANSYS (Distributed ANSYS) refers to running ANSYS across multiple processors on SMP systems or DMP systems.

Feasibility of Crosslinked Acrylic Shape Memory Polymer for a Thrombectomy Device.

PurposeTo evaluate the feasibility of utilizing a system of SMP acrylates for a thrombectomy device by determining an optimal crosslink density that provides both adequate recovery stress for blood clot removal and sufficient strain capacity to enable catheter delivery.MethodsFour thermoset acrylic copolymers containing benzylmethacrylate (BzMA) and bisphenol A ethoxylate diacrylate (Mn~512, BPA) were designed with differing thermomechanical properties. Finite element analysis (FEA) was performed to ensure that the materials were able to undergo the strains imposed by crimping, and fabricated devices were subjected to force-monitored crimping, constrained recovery, and bench-top thrombectomy.ResultsDevices with 25 and 35 mole% BPA exhibited the highest recovery stress and the highest brittle response as they broke upon constrained recovery. On the contrary, the 15 mole % BPA devices endured all testing and their recovery stress (5 kPa) enabled successful bench-top thrombectomy in 2/3 times, compared to 0/3 for the devices with the lowest BPA content.ConclusionWhile the 15 mole% BPA devices provided the best trade-off between device integrity and performance, other SMP systems that offer recovery stresses above 5 kPa without increasing brittleness to the point of causing device failure would be more suitable for this application.

ComplexSim: a flexible simulation platform for complex systems

This paper describes ComplexSim, a C-based simulation platform intended to support the study of P2P systems and complex networks. Its architecture is based on two layers: 1) the parallel simulation kernel, which manages the execution of simulations on SMP systems, by providing a clean API enabling the definition and scheduling of tasks and events; 2) the complex network data and runtime, which allows a complex network to be defined as a graph of entities endowed with user-defined attributes and runtime behaviour. This paper describes the design of ComplexSim as well as the API it provides. Moreover, some experimental results are reported, showing that, even in the case of huge complex networks with hundred million nodes, ComplexSim exhibits better performances, in terms of memory consumption and processing times, with respect to similar solutions.

Optimizing dataflow applications on heterogeneous environments

The increases in multi-core processor parallelism and in the flexibility of many-core accelerator processors, such as GPUs, have turned traditional SMP systems into hierarchical, heterogeneous computing environments. Fully exploiting these improvements in parallel system design remains an open problem. Moreover, most of the current tools for the development of parallel applications for hierarchical systems concentrate on the use of only a single processor type (e.g., accelerators) and do not coordinate several heterogeneous processors. Here, we show that making use of all of the heterogeneous computing resources can significantly improve application performance. Our approach, which consists of optimizing applications at run-time by efficiently coordinating application task execution on all available processing units is evaluated in the context of replicated dataflow applications. The proposed techniques were developed and implemented in an integrated run-time system targeting both intra- and inter-node parallelism. The experimental results with a real-world complex biomedical application show that our approach nearly doubles the performance of the GPU-only implementation on a distributed heterogeneous accelerator cluster.

Ada and cc-NUMA architectures what can be achieved with Ada 2005?

Real-time systems are finding it difficult to make the shift from single processor systems to multiprocessors because of the lack of support from programming platforms for multiprocessors. Although, Ada provides some support for SMPs, it's goal is to hide the complexity of the architectures so that the programmers are not distracted by low-level architectural issues. This paper argues that programmer should be given enough visibility to use the underlying architecture predictably and efficiently. We focus on the issue of memory management and memory accesses on a cc-NUMA architecture. A cc-NUMA architecture is chosen, as we believe it to be more scalable than SMP systems.

Application Performance on the Tri-Lab Linux Capacity Cluster - TLCC

In a recent acquisition by DOE/NNSA several large capacity computing clusters called TLCC have been installed at the DOE labs: SNL, LANL and LLNL. TLCC architecture with ccNUMA, multi-socket, multi-core nodes, and InfiniBand interconnect, is representative of the trend in HPC architectures. This paper examines application performance on TLCC contrasting them with Red Storm/Cray XT4. TLCC and Red Storm share similar AMD processors and memory DIMMs. Red Storm however has single socket nodes and custom interconnect. Micro-benchmarks and performance analysis tools help understand the causes for the observed performance differences. Control of processor and memory affinity on TLCC with the numactl utility is shown to result in significant performance gains and is essential to attenuate the detrimental impact of OS interference and cache-coherency overhead. While previous studies have investigated impact of affinity control mostly in the context of small SMP systems, the focus of this paper is on highly parallel MPI applications.

On sorting and load balancing on GPUs

In this paper we take a look at GPU-Quicksort, an efficient Quicksort algorithm suitable for the highly parallel multi-core graphics processors. Quicksort had previously been considered an inefficient sorting solution for graphics processors, but GPU-Quicksort often performs better than the fastest known sorting implementations for graphics processors, such as radix and bitonic sort. Quicksort can thus be seen as a viable alternative for sorting large quantities of data on graphics processors. We also take look at a comparison of different load balancing schemes. To get maximum performance on the many-core graphics processors it is important to have an even balance of the workload so that all processing units contribute equally to the task at hand. This can be hard to achieve when the cost of a task is not known beforehand and when new sub-tasks are created dynamically during execution. With the recent advent of scatter operations and atomic hardware primitives it is now possible to bring some of the more elaborate dynamic load balancing schemes from the conventional SMP systems domain to the graphics processor domain.

A general measure of district competitiveness

We propose a new general measure of district competitiveness that can be applied to both PR and SMP systems. We define competitiveness as the degree of uncertainty in the outcome of an election, and so the measure of competitiveness is the minimal number of additional votes required for any party to win one additional seat. We show that this corresponds to margin of victory in an SMP system and we illustrate how this can be computed in a PR system. We also argue that while it makes sense to take into account the total number of votes cast in the district it is also imperative to consider the number of seats contested. We compare district competitiveness in two SMP and two PR countries. The findings challenge the conventional wisdom that elections are more competitive and that local competitiveness is less variable under PR than under SMP. We finally show that the impact of competitiveness on turnout decreases with district magnitude.

FFT-split-operator code for solving the Dirac equation in 2+1 dimensions

The main part of the code presented in this work represents an implementation of the split-operator method [J.A. Fleck, J.R. Morris, M.D. Feit, Appl. Phys. 10 (1976) 129–160; R. Heather, Comput. Phys. Comm. 63 (1991) 446] for calculating the time-evolution of Dirac wave functions. It allows to study the dynamics of electronic Dirac wave packets under the influence of any number of laser pulses and its interaction with any number of charged ion potentials. The initial wave function can be either a free Gaussian wave packet or an arbitrary discretized spinor function that is loaded from a file provided by the user. The latter option includes Dirac bound state wave functions. The code itself contains the necessary tools for constructing such wave functions for a single-electron ion. With the help of self-adaptive numerical grids, we are able to study the electron dynamics for various problems in 2+1 dimensions at high spatial and temporal resolutions that are otherwise unachievable. Along with the position and momentum space probability density distributions, various physical observables, such as the expectation values of position and momentum, can be recorded in a time-dependent way. The electromagnetic spectrum that is emitted by the evolving particle can also be calculated with this code. Finally, for planning and comparison purposes, both the time-evolution and the emission spectrum can also be treated in an entirely classical relativistic way. Besides the implementation of the above-mentioned algorithms, the program also contains a large C++ class library to model the geometric algebra representation of spinors that we use for representing the Dirac wave function. This is why the code is called “Dirac++”. Program summary Program title: Dirac++ or (abbreviated) d++ Catalogue identifier: AEAS_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEAS_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 474 937 No. of bytes in distributed program, including test data, etc.: 4 128 347 Distribution format: tar.gz Programming language: C++ Computer: Any, but SMP systems are preferred Operating system: Linux and MacOS X are actively supported by the current version. Earlier versions were also tested successfully on IRIX and AIX Number of processors used: Generally unlimited, but best scaling with 2–4 processors for typical problems RAM: 160 Megabytes minimum for the examples given here Classification: 2.7 External routines: FFTW Library [3,4], Gnu Scientific Library [5], bzip2, bunzip2 Nature of problem: The relativistic time evolution of wave functions according to the Dirac equation is a challenging numerical task. Especially for an electron in the presence of high intensity laser beams and/or highly charged ions, this type of problem is of considerable interest to atomic physicists. Solution method: The code employs the split-operator method [1,2], combined with fast Fourier transforms (FFT) for calculating any occurring spatial derivatives, to solve the given problem. An autocorrelation spectral method [6] is provided to generate a bound state for use as the initial wave function of further dynamical studies. Restrictions: The code in its current form is restricted to problems in two spatial dimensions. Otherwise it is only limited by CPU time and memory that one can afford to spend on a particular problem. Unusual features: The code features dynamically adapting position and momentum space grids to keep execution time and memory requirements as small as possible. It employs an object-oriented approach, and it relies on a Clifford algebra class library to represent the mathematical objects of the Dirac formalism which we employ. Besides that it includes a feature (typically called “checkpointing”) which allows the resumption of an interrupted calculation. Additional comments: Along with the program's source code, we provide several sample configuration files, a pre-calculated bound state wave function, and template files for the analysis of the results with both MatLab and Igor Pro. Running time: Running time ranges from a few minutes for simple tests up to several days, even weeks for real-world physical problems that require very large grids or very small time steps.

Hymenolepis diminuta: Mitochondrial transhydrogenase as an additional site for anaerobic phosphorylation

Employing adult Hymenolepis diminuta SMP and exogenous pyridine nucleotide-generating systems, reduced pyridine nucleotide-dependent net 32P incorporation into ATP was examined. NADH supported rotenone-sensitive 32P incorporation and this rate increased markedly with fumarate addition, in keeping with an active fumarate reductase. Interestingly, corresponding evaluations with NADPH did not result in detectable phosphorylation in the absence or presence of fumarate. However, with NAD addition, but without NAD generation, active NADPH-dependent phosphorylation occurred, thereby demonstrating mitochondrial transhydrogenase involvement, and 32P incorporation increased significantly with fumarate addition. More importantly, in the presence of rotenone and both NADPH and NAD generation, significant net 32P incorporation was noted, but was undetectable in the presence of DCCD or protonophores (e.g., niclosamide). Without NAD generation, minimal phosphorylation occurred. These data demonstrate that with ongoing NADPH and NAD generation, the H. diminuta, proton-translocating, mitochondrial transhydrogenase can serve as an additional anaerobic phosphorylation site. A model is presented.

A Next-Generation Enterprise Server System with Advanced Cache Coherence Chips

Broadcast and synchronization techniques are used for cache coherence control in conventional larger scale snoop-based SMP systems. The penalty for synchronization is directly proportional to system size. Meanwhile, advances in LSI technology now enable placing a memory controller on a CPU die. The latency to access directly linked memory is drastically reduced by an on-die controller. Developing an enterprise server system with these CPUs allows us an opportunity to achieve higher performance. Though the penalty of synchronization is counted whenever a cache miss occurs, it is necessary to improve the coherence method to receive the full benefit of this effect. In this paper, we demonstrate a coherence directory organization that fits into DSM enterprise server systems. Originally, a directory-based method was adopted in high performance computing systems because of its huge scalability in comparison with snoop-based method. Though directory capacity miss and long directory access latency are the major problems of this method, the relaxed scalability requirement of enterprise servers is advantageous to us to solve these problems along with an advanced LSI technology. Our proposed directory solves both problems by implementing a full bit vector level map of the coherence directory on an LSI chip. Our experimental results validate that a system controlled by our proposed directory can surpass a snoop-based system in performance even without applying data localization optimization to an online transaction processing (OLTP) workload.

Coupled cluster algorithms for networks of shared memory parallel processors

Abstract As the popularity of using SMP systems as the building blocks for high performance supercomputers increases, so too increases the need for applications that can utilize the multiple levels of parallelism available in clusters of SMPs. This paper presents a dual-layer distributed algorithm, using both shared-memory and distributed-memory techniques to parallelize a very important algorithm (often called the “gold standard”) used in computational chemistry, the single and double excitation coupled cluster method with perturbative triples, i.e. CCSD(T). The algorithm is presented within the framework of the GAMESS [M.W. Schmidt, K.K. Baldridge, J.A. Boatz, S.T. Elbert, M.S. Gordon, J.J. Jensen, S. Koseki, N. Matsunaga, K.A. Nguyen, S. Su, T.L. Windus, M. Dupuis, J.A. Montgomery, General atomic and molecular electronic structure system, J. Comput. Chem. 14 (1993) 1347–1363]. (General Atomic and Molecular Electronic Structure System) program suite and the Distributed Data Interface [M.W. Schmidt, G.D. Fletcher, B.M. Bode, M.S. Gordon, The distributed data interface in GAMESS, Comput. Phys. Comm. 128 (2000) 190]. (DDI), however, the essential features of the algorithm (data distribution, load-balancing and communication overhead) can be applied to more general computational problems. Timing and performance data for our dual-level algorithm is presented on several large-scale clusters of SMPs.