Fast GPU-Based Generation of Large Graph Networks From Degree Distributions

Synthetically generated, large graph networks serve as useful proxies to real-world networks for many graph-based applications. The ability to generate such networks helps overcome several limitations of real-world networks regarding their number, availability, and access. Here, we present the design, implementation, and performance study of a novel network generator that can produce very large graph networks conforming to any desired degree distribution. The generator is designed and implemented for efficient execution on modern graphics processing units (GPUs). Given an array of desired vertex degrees and number of vertices for each desired degree, our algorithm generates the edges of a random graph that satisfies the input degree distribution. Multiple runtime variants are implemented and tested: 1) a uniform static work assignment using a fixed thread launch scheme, 2) a load-balanced static work assignment also with fixed thread launch but with cost-aware task-to-thread mapping, and 3) a dynamic scheme with multiple GPU kernels asynchronously launched from the CPU. The generation is tested on a range of popular networks such as Twitter and Facebook, representing different scales and skews in degree distributions. Results show that, using our algorithm on a single modern GPU (NVIDIA Volta V100), it is possible to generate large-scale graph networks at rates exceeding 50 billion edges per second for a 69 billion-edge network. GPU profiling confirms high utilization and low branching divergence of our implementation from small to large network sizes. For networks with scattered distributions, we provide a coarsening method that further increases the GPU-based generation speed by up to a factor of 4 on tested input networks with over 45 billion edges.

A possible revival of population-representing digital human manikins in static work situations –exemplified through an evaluation of a prototype console for robotic surgery

BACKGROUND: In the 90s, digital human manikins (DHMs) were introduced in planning of workstations, by static or semi-static simulations. Modern DHMs can simulate dynamic work and offer a rapid way for a virtual pre-production ergonomic evaluation. Work-related musculoskeletal disorders may affect surgical performance and patient safety. A prototype of an open console, which is contrary to the conventional closed consoles and may be seen as a representative for a new generation, has been designed to reduce workload for robotic surgery surgeons. OBJECTIVE: The aim of this project was to test a new DHM tool with improved usability to evaluate the ergonomics of console of a robotic surgical system in a pre-production stage. METHODS: The DHM tool IMMA was used together with a 3D model of the prototype console. Twelve manikins who represented females and males from two national populations were introduced. Manikin-console distances, after console adjustments per manikin, were compared with a US checklist and Swedish standards for VDU work. RESULTS: The DHM tool was useful for this case, but the distances of the checklist and the standards were needed to be obtained “manually”. The automatic functions of the DHM worked smoothly but were not optimized for VDU work. The prototype fulfilled most, but not all, of the ergonomic criteria of the checklist and the standards. CONCLUSIONS: There is room for improvements of the adjustable ranges of the console prototype. DHMs may facilitate rapid pre-production evaluation of workstations for static work; if ergonomic assessment models for VDU work are built-in, there may be a revival of DHMs in static work situations.

The Effect of Subgrade Coefficient on Static Work of a Pontoon Made as a Monolithic Closed Tank

This article presents the effect of taking into account the subgrade coefficient on static work of a pontoon with an internal partition, made in one stage and treated computationally as a monolithic closed rectangular tank. An exemplary pontoon is a single, ready-made shipping element that can be used as a float for a building. By assembling several floats together, the structure can form a floating platform. Due to the increasingly violent weather phenomena and the necessity to ensure safe habitation for people in countries at risk of inundation or flooding, amphibious construction could provide new solutions. This article presents calculations for a real pontoon made in one stage for the purpose of conducting research. Since it is a closed structure without any joint or contact, it can be concluded that it is impossible for water to get inside. However, in order to exclude the possibility of the pontoon filling with water, its interior was filled with Styrofoam. For static calculations, the variational approach to the finite difference method was used, assuming the condition for the minimum energy of elastic deflection during bending, taking into account the cooperation of the tank walls with the Styrofoam filling treated as a Winkler elastic substrate and assuming that Poisson’s ratio ν = 0. Based on the results, charts were made illustrating the change in bending moments at the characteristic points of the analysed tank depending on acting loads. The calculations included hydrostatic loads on the upper plate and ice floe pressure as well as buoyancy, stability and metacentric height of the pontoon. The aim of the study is to show a finished product—a single-piece pontoon that can be a prefabricated element designed for use as a float for “houses on water”.

DESIGN OPTIMIZATION OF MOVEABLE MOMENT STABILIZATION SYSTEM FOR ACCESS CRANE PLATFORMS

The popularity of aerial work platforms is rapidly increasing in the mechanization industry. As a result, the safety and structural strength of aerial work platforms should be prioritized.In this study, the mathematical model of a reconstructed aerial work platform was developed and a 3D model was created using the Solidworks software. A dynamic analysis was then performed to improve various structural parameters of the aerial work platform. The analysis was carried out using solid modelling, finite elements, and dynamic transient analysis. In compliance with international structural standards, the weight distribution was reconstructed after placing a mass behind the turret.The results of the dynamic transient analysis were compared with the mathematical model and validated. Then, the effect of the mass placed behind the turret on the machine was examined. The lateral tipping distance of the static work platform was found to have increased from 15.9m to 17.08 m. The structure of the aerial work platform was improved using a structural and dynamic analysis approach. It was also discovered that the machine efficiency could be further increased by ensuring that the balancing weight is moved further away from the tower centre by a hydraulic-based system and controller.

Numerical Analysis of the Bottom Thickness of Closed Rectangular Tanks Used as Pontoons

This paper concerns the numerical analysis of closed rectangular tanks made in one stage, used as pontoons. Such structures can be successfully used as floating platforms, although they primarily serve as floats for ‘houses on water’. Amphibious construction has fascinated designers for many years and is becoming, in addition to a great and prestigious location for many purposes, a practical global necessity. Severe weather phenomena that no country is safe from, i.e., heavy rains or floods, combined with the scarcity of space intended for the construction of residential buildings, encourage development at the contact of water and land or on water only. This paper contains an analysis of the static work of tanks with different bottom thickness subjected to hydrostatic load acting on tank walls and the bottom plate and evenly distributed load acting on the upper plate, i.e., major impacts that occur when tanks are used as pontoons. Calculations were made using the finite difference method in terms of energy, assuming the Poisson’s ratio ν = 0. Based on the solutions obtained, charts were made that illustrated the change in bending moments at the characteristic points of the analysed tanks depending on acting loads. The article also includes calculations of buoyancy, stability and the metacentric height for tanks with different bottom thicknesses, with the main purpose being to improve and share knowledge on their safe use as pontoons.

AUTHOR'S METHOD OF CONTINUUM STATES ON THE EXAMPLE OF IMPERFECTION IN THE CONSTRUCTION OF A LARGE-PANEL BUILDING

The paper presents the results of FEM computer analysis regarding cracking of the wall prefabricated element. The proprietary coating model of the Wk-70 System large-panel building construction was used. For analysis, a construction diaphragm has been separated that is integrally connected to the vertical communication structure. Modeled through the scratch in the attic wall and compared with the wall model without damage. By building the shell model, a real and transparent picture of the static work of the structure was obtained, distinguishing zones: focus, redistribution, compensation and neutralization of stresses, whose genesis results from imperfection - scratches in a reinforced concrete composite. For the first time, the author introduces his own method of assessing the safety status of large-panel buildings - by the States Continuum Method.

Mechanical Properties of Laminated Veneer Lumber Beams Strengthened with CFRP Sheets

This paper presents the results of the static work analysis of laminated veneer lumber (LVL) beams strengthened with carbon fabric sheets (CFRP). Tested specimens were 45mm wide, 100 mm high, and 1700 mm long. Two types of strengthening arrangements were assumed as follows: 1. One layer of sheet bonded to the bottom face; 2. U-shape half-wrapped reinforcement; both sides wrapped to half of the height of the cross-section. The reinforcement ratios were 0.22% and 0.72%, respectively. In both cases, the FRP reinforcement was bonded along the entire span of the element by means of epoxy resin. The reinforcement of the elements resulted in an increase in the bending strength by 30% and 35%, respectively, as well as an increase in the global modulus of elasticity in bending greater than 20% for both configurations (in comparison to the reference elements).

EXPERIMENTAL STUDY OF THE VOLATILE PETROLEUM PRODUCTS EFFECT ON THE CENTRAL NERVOUS SYSTEM

Objective: The goal of the research is studying the functional changes in the central nervous system against the background of intoxication with the minimum dosages of gasoline, benzene and acetone.Methods: The research was performed on 45 white mice divided into 3 groups; each group received corresponding hydrocarbon in the exposure chamber by inhaling. The functional state of the CNS was assessed with a complex of integral tests: By summation of subliminal pulses, the ability of animals to restore rectilinear movement after centrifugation, by the tone of skeletal muscles, and by the activity of muscle static work.Results: The durations of the narcosis phases in case of acute inhalation poisoning are different for all studied substances. The study of the functional changes in the CNS on the background of intoxication with low dosages has revealed that at the first exposure to benzene for activating the motor reaction the required number of electric pulses from the outside increases, the muscle tone increases, the ability to static work reduces, and the time for rectilinear movement and “animal hypnosis” increases. At the same time, on the background of intoxication during the fifth exposure, a decrease is observed in the number of electric pulses from the outside for activating the motor reaction, the muscle tone remains increased, the ability to static work is reduced, and the time of “animal hypnosis” is shorter than that during the first exposure.Conclusion: Against the background of the repeated use of small doses of benzene, the CNS adapts to the action of the toxic factor. With that, the ability of the CNS to sum the subliminal pulses, the cholinergic innervation of the skeletal muscles tone and other integral tests during the fifth exposure change less than during the first exposure.