Set Of Bars Research Articles

Designing Robotically‐Constructed Metal Frame Structures

AbstractWe present a computational technique that aids with the design of structurally‐sound metal frames, tailored for robotic fabrication using an existing process that integrate automated bar bending, welding, and cutting. Aligning frames with structurally‐favorable orientations, and decomposing models into fabricable units, we make the fabrication process scale‐invariant, and frames globally align in an aesthetically‐pleasing and structurally‐informed manner. Relying on standard analysis of frames, we then co‐optimize the shape and topology of bars at the local unit level. At this level, we minimize combinations of functional and aesthetic objectives under strict fabrication constraints that model the assembly of discrete sets of bent bars. We demonstrate the capabilities of our global‐to‐local approach on four robotically‐constructed examples.

Simulation study on the effect of fuel injection and air intake boundary setup on the brake torque response by using comprehensive vehicle model for natural gas vehicle (NGV)

An analytical, dynamic and comprehensive vehicle model, replicated a high-pressure direct injection compressed natural gas (HPDI-CNG) engine in a vehicle is proposed with the objective to study the effect of fuel injection and air intake boundary condition on the brake torque response. The model simulated the output torque in transient simulations of the natural gas vehicle (NGV) in speed-sweep mode test. The vehicle model has coupled an analytical engine model developed in Simulink with a Simscape driveline model which consists of a clutch model, a simple transmission gear and a simplified vehicle model. In all problem, independent input to the model is the throttle opening ramp. The adjusted parameter in the first study is the methods to calculate the mass of fuel inlet which is based on i) fully experimental data, ii) measured air to fuel ratio (AFR) and (iii) constant injector mass flow rate. In the second problem, the pressure limit of the manifold absolute pressure (MAP) is adjusted as (i) fully experimental data (ii) 1.2 bar (iii) 1.5 bar and (iv) unlimited pressure limit. The dependent parameter in all problem is engine output torque. The results have been compared with the actual data of torque from chassis dynamometer measurement. For the effect of fuel inlet boundary set up, in the fully predictive mode, the model predicted an almost constant maximum torque at a value about 70 Nm, whereas the measured data only produced the same peak value at a very limited instant. If the model used measured AFR as the fuel input boundary, the model overpredicted the maximum peak torque of 70 Nm. In the study on the effect of MAP limit, the maximum torque for 1.2 bar, 1.5 bar and unlimited pressure set up has produced a maximum torque of 45, 62 and 70 Nm, respectively. Results of the first study showed that the use of constant injector mass flow rate has a tendency to simulate an ideal engine acceleration process. The prediction is closed to the measured data if the fuel mass is calculated based on the measured AFR. However, the use of measured AFR in our opinion have reduced the model predictability. In the second study, the increased MAP limit significantly increased the maximum brake torque response. However, the model cannot predict the abnormalities found in the experimental data. The use of MAP limit demonstrated the sensitivity of the output torque on the maximum value of the engine MAP. The results indicated that the injection fuel inlet boundary and the MAP limit have a strong significance on the model prediction and need to be improved for future use of the model.

Durability study of concrete-covered basalt fiber-reinforced polymer (BFRP) bars in marine environment

To understand the durability of basalt fiber-reinforced polymer (BFRP) bars for the reinforcement of concrete structures applied in marine environments, BFRP bars with 20-mm concrete covers were immersed in ocean water or simulated seawater at room temperature (~23 °C), and the evolution of the thermomechanical properties was studied. A set of uncovered BFRP bars immersed in ocean water and laboratory accelerated simulated seawater (23 °C, 40 °C, and 60 °C) was investigated for comparison. After one year, the mechanical properties of the uncovered BFRP immersed in 60 °C simulated seawater showed the most degradation, followed by the concrete-covered BFRP in the laboratory immersion. Concrete-covered BFRP showed more deterioration than uncovered BFRP in the ocean water. The results indicated that the alkalinity is the key factor causing the degradation of BFRP, especially for standing water in the laboratory environment. In addition, an alkali-aggregate reaction (AAR) of SiO2 in basalt fiber was found at the interface between the BFRP bars and concrete. The degradation of the resin matrix and sizing led to the direct exposure of basalt fiber to alkaline solution, which established the foundation of the AAR.

Modelling of Multi-Storey Frame Interacting with Rigid Core of the Building

Impact of bar incompressibility assumption on frames has been analysed in this paper. It has been shown, that in some cases of high buildings, where rigid core is surrounded by set of bars, assumption of columns incompressibility is justified. With compressible bars, significant bending moments occurs on beams connected to core of the building.

An Animal’s Environment Influences Perceptions of Docility and Vigor But Not Aesthetic Appeal: A Constructive Replication

Shifts toward naturalistic zoo enclosures in the last decades of the 20th century prompted research findings that perceptions of animals were influenced by their environment. The current study replicated and expanded upon that prior work. University students ( n = 1,253) viewed animals in wild, naturalistic, front cage bar, or back cage bar settings with a name-only control and rated each animal on 11 semantic characteristics. Exploratory factor analysis of those ratings revealed underlying constructs of aesthetic appeal, docility, and vigor. Women perceived animals as more aesthetically appealing than did men. Perceptions of docility increased and vigor decreased as the naturalness of the environment declined. Measures of nature relatedness and environmental motives were not altered by viewing different environments but those traits influenced perceptions of aesthetic appeal. The current findings show that environment alters some but not all of the elements of how animals are perceived by the public.

Biased Average Position Estimates in Line and Bar Graphs: Underestimation, Overestimation, and Perceptual Pull.

In visual depictions of data, position (i.e., the vertical height of a line or a bar) is believed to be the most precise way to encode information compared to other encodings (e.g., hue). Not only are other encodings less precise than position, but they can also be prone to systematic biases (e.g., color category boundaries can distort perceived differences between hues). By comparison, position's high level of precision may seem to protect it from such biases. In contrast, across three empirical studies, we show that while position may be a precise form of data encoding, it can also produce systematic biases in how values are visually encoded, at least for reports of average position across a short delay. In displays with a single line or a single set of bars, reports of average positions were significantly biased, such that line positions were underestimated and bar positions were overestimated. In displays with multiple data series (i.e., multiple lines and/or sets of bars), this systematic bias still persisted. We also observed an effect of "perceptual pull", where the average position estimate for each series was 'pulled' toward the other. These findings suggest that, although position may still be the most precise form of visual data encoding, it can also be systematically biased.

Bayesian inference for variability discrimination on partial sameness

The comparative judgment about the partial sameness is widespread in practical visual search tasks. We explore the variability discrimination on the partial sameness by the means of experiments and theoretical models. In experiments, a set of bars with the aim orientation and random orientations are shown on a liquid crystal display (LCD), and the subjects judge the orientations of bars and record the number of bars with the same aim orientation. In comparative experiments, the three-digit integers replace the oriented bar as the new stimuli. By the visualized data of subjects, we find that the performances of subjects depend on the total number of bars (set size), the number of bars with the identical aim orientation and the standard deviation of the orientations’ distribution. Based on Bayesian theory, we put forward a model in visual search to judge how many bars with the same orientation. The results show that Bayesian discrimination model on this kind of classified judgment matches the experimental data better than the alternative model, and it provides a normative and quantitative description on the judgment of the partial sameness.

Form-Finding and Structural Shape Optimization of the Metal 3DPrinted Multi-Branch Node with Complex Geometry

The application of additive manufacturing (AM) technology in architecture and structural engineering has been extended due to recent development of metal 3d printing. In space frame structures, a set of bars is configured in three dimensions, with bars connected by nodes. This article presents two methods to design metal 3d-printed multi-branch nodes to accommodate any number of incident bars at arbitrary angles. Resulting node designs are intended to be smooth and lightweight. A multi-branch node is sketched using the dimensional information of the blank space between the converging bars in a pre-designed space frame and then parameterized by two different approaches to perform structural optimization. The first design method, namely the curve parameter method, which is semi-automated approach, the distances between the control points of the spline curves between node branches and the node branch intersection point are the optimization parameters. For the other method, called fatness parameter method, which is a fast and automated approach, the fatness parameters of the center part of the node and the root radiuses of each branch are chosen as the main parameters of optimization. The optimization procedure is accomplished using a genetic algorithm to minimize the maximum von Mises stress as the objective function subjected to the mass of the node as a constraint function. Finally, functional tests are conducted on 3D printed metal nodes in order to compare the strength and stiffness of the nodes designed by the two form-finding approaches.

Alcohol mixed energy drink use as a risk factor for experiencing and perpetrating bar aggression.

Despite the recent, widespread trend of consuming alcohol mixed with energy drinks (AmEDs) in commercial bar settings, few studies have examined whether this practice exacerbates the risk of experiencing aggression in bars and licensed establishments. Past studies have been limited to between-subjects comparison analyses that are at risk for bias due to selection effects. The present analysis examines whether a sample of individuals who regularly use AmEDs are at elevated risk for experiencing or perpetrating physical aggression in bars when drinking AmEDs versus when they are drinking noncaffeinated alcohol (NCA) use alone. This within-subject analysis controls for any individual differences that may be related to both AmED use and the tendency to engage in aggressive behavior. An online survey was completed by 175 young adults (78 male) who were frequent bar patrons, used AmEDs regularly, and had experienced at least one recent bar conflict incident. Although NCA use was more common than was AmED use, AmED-involved bar aggression was more frequently reported than was aggression that coincided with NCA use only. Additionally, victimization and perpetration of aggression in bar environments were both more common when AmEDs were used than when only NCA was used. Frequency of going to bars was predictive of rates of experiencing bar aggression only when drinking NCA but not when drinking AmEDs. Results suggest that AmED use introduces a unique risk factor into the bar environment that must be considered in future research and in subsequent interventions meant to reduce the incidence of bar aggression. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Efficient Simulation of RC Shear Walls in High-Rise Buildings Using a Practical Multi-Cross-Line-Model

ABSTRACT This paper presents a novel model for reinforced concrete (RC) shear walls, named as multi-cross line model (MCLM), combining the concepts of micro- and macro-shear wall models by simulating the stress–strain relationships at the material level using a set of concrete or steel bars, and thereof calculating the resultant stresses. The two-dimensional MCLM jointly with the multilayer shell element can simulate the three-dimensional behaviors of the RC shear walls. The proposed model is validated by using three RC shear wall specimens under cyclic loading conditions. Besides, the huge potential for practical use of this model is also illustrated.

Simple optimal lattice structures for arbitrary loadings

This paper identifies four categories of optimal truss lattice structures (TLSs) that together provide ultimate stiffness for arbitrary multi-loading scenarios in the low volume fraction limit. Each category consists of 7 periodic sets of straight bars, forming periodic parallelepiped unit cells. Compared to other optimal TLSs, the identified TLSs most probably have the simplest possible geometries with the least number of bar sets. Macroscopic properties of a TLS are estimated using a superposition model, and an optimization problem is solved to determine the exact geometries of the optimal TLSs. Systematic optimization results, run for thousands of random multi-loading conditions, are compared to (postulated) theoretical bounds for both truss and plate lattice structures. The results clearly demonstrate near-optimality of the identified TLSs (relative difference mostly within machine precision except in few cases up to 0.1%) for any loading scenarios in linear elasticity. At the same time, the optimal anisotropic TLSs always have inferior stiffness to the corresponding optimal plate lattice structures and this inferiority is bounded between 1 (single uniaxial load) and a factor of 3 (optimal isotropy).

Wind Farm: Four Variations

Wind Farm:Four Variations Jeff Gundy (bio) It is time for all the heroes to go homeif they have any … -William Stafford, "Allegiances" A big wind farm runs across the farm I grew up on and for miles to the west and north, a hundred or so towers combing the wind day and night, their giant arms turning, red lights blinking in unison through the nights. Some communities have fought to keep them out, claiming they kill birds, confuse human thought patterns with their churning, even disturb weather patterns, or might, or could, but here they are. They seem strange and wonderful to me, but I'm only around for a couple of days once or twice a year when we make it out to see my parents. The beauty of windmills is awkward and pragmatic, like the great blue heron's—or, better, the great egret, which is snowy white as the windmills. A beauty years in the making, expensive and complicated, an engineered and calculated beauty requiring access roads and giant [End Page 5] cranes, buried cables linking the great spindly machines. They are lonesome even in their clusters, keeping their distance, the way farmers have always been lonesome. The giant blades thrum their two notes day and night, yielding to and using the invisible wind, sifting it for power, sending it off to be used with no knowledge of where, of how. I've never seen an egret or a heron near the farm. A few might wander through the area, dip down to hunt in Scattering Point Creek to the east, but there's very little open water on the wind farm. I've been gone for nearly half a century, yes, but still I'm pretty sure they're rare. On the farm where I grew up, as far back as I can remember, a big raw steel windmill tower stood in place for decades, unused, a little rusty but sound. A buried electric pump pulled water from our well. The windmill on Vernon's place was still working, I think, when I was young—I remember a water tank between the legs. Electric pumps was more reliable, more practical, much less picturesque. When did those towers come down, and who did the work? If I had been a bolder kid I would have climbed them. I don't think I ever did, at least not high. I think now that my dad took the ladder down to keep us kids on the ground. That would have been sensible and tragic, and entirely fitting. Our well was reliable but the water was not good—sometimes full of rust, sometimes rotten-egg heavy with sulfur. My dad spent lots of money on treatment systems, hours trying to adjust and cajole them into working. The new windmills are something else entirely. Some people call them ugly, mostly for reasons having nothing to do with aesthetics. I suspect the resistance to wind farms is more political than people want to admit, but I also must admit I don't really know. If it's ugly we're talking about, though, we need to talk about the whole enterprise of industrial agriculture, the gridded landscape and the skinned prairies turned to monocultures, herbicides, pesticides, chemical fertilizer, all the rest. The roads, like a set of giant bars across a third of a continent, practical in the extreme if you're not a pheasant or big bluestem or a nomadic hunter-gatherer. [End Page 6] I Hear the Drumming There's a new song, Rick said, a protest song, it's pretty good. He was a Latino kid from Chicago who'd come to live at the Children's Home. Some of them were pretty tough, but Rick and his brother Tony just wanted to play music. They could do covers with every note perfect. I was equally in love with the music, could find the chords and keep a tune, but already I could tell that precise imitation would never be my strong suit. This was summer 1970 and I'd just escaped from high school. We'd ridden a bus all night to someplace in the Smokies...

Study on the Low and High Strain Rate Behavior of Fumed Nano Silica Dispersions

Shear Thickening Fluids (STFs) are a special class of field responsive non-Newtonian fluids which exhibit transition from low viscosity to high viscosity state when they are subjected to shearing deformation above the critical shear rate (CSR). Due to this unique characteristic of STFs, these have found application in ballistics, especially in the development of special class of body armors called Liquid Body Armors (LBAs) which are lighter in weight and more flexible as compared to conventional heavy armours. Fumed silica (FS) is a rheologically significant material as it is a well known viscosity modifier owing to its fractal structure, and is generally used in paints, coatings, sealants, printing inks etc. In this study, two different grades of FS (A-130 and A-150) were used for the synthesis of STFs. The low strain rate studies were conducted on cone and plate rheometer and high strain rate experiments were accomplished on split Hopkinson pressure bar (SHPB) set up. The colloidal dispersions in PPG-400 (Poly Propylene Glycol 400) were synthesized using ultrasonic homogenization technique. From the experiments it was observed that A-150 fumed silica dispersion exhibited higher severity in shear thickening in the low strain rate domain, whereas A-130 fumed silica dispersion exhibited higher specimen stress and compressional strain rate under high strain rate dynamic compressive loading. Thus, it can be inferred that the same material may exhibit different behaviors in the low and high strain rate regimes. Therefore, both the studies play a vital role to completely characterize the material, especially when the material has to be subjected to ballistic applications.

Global rigidity of triangulations with braces

A.L. Cauchy proved that if the vertex-edge graphs of two convex polyhedra are isomorphic and corresponding faces are congruent then the two polyhedra are the same. This result implies that a convex polyhedron with triangular faces, as a bar-and-joint framework, is rigid.A framework is said to be globally rigid if the bar lengths uniquely determine all pairwise distances between the joints. Global rigidity implies rigidity. It is well-known that every three-dimensional generic bar-and-joint realisation of the graph of a convex polyhedron with triangular faces (that we call a triangulation) is rigid. It is also known that if the number of vertices is at least five then such a realisation of a triangulation is never globally rigid.In this paper we consider braced triangulations, obtained from triangulations by adding a set of extra bars (bracing edges) connecting pairs of non-adjacent vertices. We show that a braced triangulation is generically globally rigid in three-space if and only if it is 4-connected. The special case, when there is only one bracing edge, verifies a conjecture of W. Whiteley.Our proof is based on a new result on the vertex splitting operation which may be of independent interest. We show that every graph which can be obtained from the complete graph on five vertices by non-trivial vertex splitting operations is generically globally rigid in three-space.

Variable high‐pressure and concentration study of cyclohexane pyrolysis at high temperatures

AbstractA high‐pressure and temperature cyclohexane pyrolysis shock tube study was completed with the goal of extending the experimental cyclohexane pyrolysis data to pressures relevant to current and future combustors and to investigate whether ring contraction products observed in high‐pressure, supercritical phase cyclohexane and cycloalkane pyrolysis experiments can form at matching, and higher, pressures in the gas phase. The experiments in the current work were completed over a range of 950–1650 K and at nominal pressures of 40, 100, and 200 bar. No alkylcyclopentanes, possible ring contraction products, were observed to form under the conditions of the current study. The production of methylenecyclopentane and 1,3‐cyclopentadiene, and the other three cyclic species quantified: cyclohexene, benzene, and toluene, increased significantly with a substantial increase in the initial fuel concentration. Two sets of experimental data obtained at 200 bar were compared with a literature and laboratory‐generated model. Both models had difficulty capturing the propadiene and propyne profiles, and the literature model significantly overestimated the benzene observed in the set of experiments completed with the more dilute fuel mixture. The literature model was able to better predict propadiene, propyne, and benzene product profiles in the 200 bar set of experiments, which used a higher concentration of fuel in the test gas. These results suggest that despite both cyclohexane and benzene being well‐studied and important species in combustion chemistry, their reaction pathways and reaction rates would benefit from further refinement.

Comparison of Lowest-Slot and Nearest-Stack Heuristics for Storage Assignment of Steel Bar Sets

Abstract Our research objective is to lower intralogistics costs by minimizing the number of shuffling operations in a steel plant company commercial warehouse. The process of dispatching products consists of retrieving set of steel bar (SSB) from a floor stored stack or a special stacking frame by an overhead crane. To retrieve a targeted merchandise all SSB above targeted must be reshuffled. Proper assignment of storage locations is a key logistics problem for efficient order picking. We are comparing two heuristics, that do not require information of dispatching sequence of any stored products. We simulated the problem at hand with both methods. Our objective is to count the number of reshuffles using each heuristic on randomly generated examples and decide which is better in the long run. Our problem has similarities with storage assignment of steel plates or steel coils for minimization of reshuffling operations. The problem is also comparable to storage assignment of containers in a container yard. In our case we are dealing with a special stacking configuration of products, that demands different approach. We want to demonstrate which heuristic should be used in companies that lack necessary storage information infrastructure.

Academic productivity in surgical oncology: Where is the bar set for those training the next generation?

Promotion and tenure are important milestones for academic surgical oncologists. The aim of this study was to quantify academic metrics associated with rank in surgical oncologists training the next generation. Faculty were identified from accredited surgical oncology fellowships in the United States. Scopus was used to obtain the number of publications/citations and h-index values. The National Institutes of Health (NIH) RePORT website was used to identify funding history. Of the 319 surgeons identified, complete rank information was obtained for 308. The majority of faculty were men (70%) and only 11% of full professors were women. The median h-index values were 7, 17, and 39 for assistant, associate, and full professors, respectively. While 50% of full professors had a history of NIH funding, only 26%had RO1s and 20% had current NIH funding. Using multivariate analysis, years in practice, h-index, and a history of NIH funding were associated with academic rank (P < .05). Objective benchmarks, such as the median h-index and NIH funding, provide additional insights for both junior faculty and leadership into the productivity needed to attain promotion to the next academic rank for surgical oncologists.

Forensic Exploration of the Mechanical Properties of Basalt Grains in Earthenware

The overall goal of this project is to contribute to reconstruct the innovation mechanisms and development of ceramic production using forensic engineering techniques. Instead of optimizing materials as a driver in modern engineering, here we wish to use these methodologies, but aim to solve questions on advancement in the past fabrication process – and thus ultimately understand the key issues of a less or (un)successful design and subsequent improvement. This paper wishes to address the advantages and constraints regarding to use of basalt in ceramic matrices. By utilizing a standardized set of different test bars comprising different amounts of basalt fired at both 800°C and 1000°C, it can be concluded basalt tempered ceramics have a higher fracture toughness when compared to quartz enriched materials. It is there plausible to identify basalt as a good temper material for (ancient) earthenwares in terms of thermal (shock) activities.

Power Quality Performance Analysis of grid tied PV fed Parallel Pumping System under Normal and Vibrating Condition

The aim of this paper is to perform the relative study of power quality problems in a grid tied solar PV system, with and without vibration connected to a parallel pumping system at 1.0 bar set pressure by using two control techniques such as VVC+ & V/f. In case of vibrations, the effect of motor vibration problems on the dynamic performance and electrical power quality of water pumping system will be observed. Vibrations are introduced in the pumping system by loosening the base plate of the pumps. During motor vibrations, the instantaneous flicker values become high which leads to variation in the supply voltage and torque imbalance. The effect of power quality parameters in a solar feeder during normal conditions and vibrating conditions are analysed. In normal condition, the THD increases and the flicker is high only during transient period due to sudden voltage variations. A comparison has been made to observe the appropriate control method for pumping system with and without vibrations in a solar PV-grid connected system.

Quantity discrimination by treefrogs

To make foraging, reproductive and antipredator decisions, animals often have to discriminate discrete and continuous quantities (numbers and sizes of objects, respectively). Few studies have investigated discrete quantity discrimination in amphibians, but this has been done only in the context of prey selection. Using a species with arboreal habits, the Italian treefrog, Hyla intermedia, we investigated whether amphibians discriminate both discrete and continuous quantities when choosing between microhabitats. In field experiments, we showed that newly metamorphosed treefrogs exhibit a preference for microhabitats with abundant and tall grass. In the laboratory, treefrogs presented with the dichotomous choice between two sets comprising different numbers of vertical green bars (simulating grass clumps) showed a preference for the larger set and discriminated between 1 and 2 bars and between 2 and 4 bars, but not between 2 and 3 bars and between 3 and 4 bars. When presented with two bars of different size (i.e. one bar was taller and wider), treefrogs preferred the larger bar up to a 0.25 surface area ratio. Control experiments suggested that treefrogs represent numbers rather than continuous variables to discriminate between sets of bars and that they use the height but not the width of the bars to discriminate sizes. We also found evidence of a possible trade-off between speed and accuracy: individuals that chose more quickly did not display a significant preference for the larger bar/set of bars. These findings suggest that for amphibians, as for other vertebrates, a variety of decision-making processes can rely on quantitative abilities.