Constrain Conditions Research Articles

Damaged RC beams strengthened with NSM CFRP rectangular rods under vibration in different constrain conditions

The strengthening of damaged reinforced concrete (RC) beams through near surface mounted (NSM) fiber reinforced polymers (FRPs) has been shown to be a suitable method in practice. Availability of this technique is based on maintaining the adhesion between FRP rods and the concrete surface of grooves, both undamaged and damaged by cracking of beams. Controlling the status of RC beams strengthened with NSM FRP rods may be carried out through non destructive experimental tests measuring dynamic parameters such as frequency values.This paper analyses experimental vibration of four RC beam models without strengthening and strengthened with NSM carbon-FRP rectangular rods after damage due to bending cracking of concrete by static tests. The investigation of vibration was carried out considering RC beams at different static loading damages in different constrain conditions: two beam models were studied assuming free-free end condition and the other two with hinge-hinge end condition. Envelope of Frequency Response Functions (FRFs) obtained through dynamic testing are shown in the paper and changes of frequency values are compared and discussed.Finally, a comparison between experimental and theoretical dynamic values obtained by finite element analysis is developed to verify the control of RC beams strengthened with NSM CFRP rods.

The optimal model of oilfield development investment based on Data Envelopment Analysis

Abstract The investment problem of oilfield development is to trade off the investment exploration investment and development investment. With low return on investment got by using the existing method to solve this problem, we construct an optimal model to improve it based on Data Envelopment Analysis (DEA) method and the relations about investment and proven reserves, investment and output as well as production cost. Data Envelopment Analysis (DEA) method is used to present a method to determine the optimal scale of productivity construction investment in unit production. The relation between total cumulated proven reserves and cumulative exploration investment is denoted as an exponential model. The relation among productions and remaining recoverable reserves as well as production cost may be described as an exponential operational cost function. Based on above two relation models and investment effectiveness coefficients of every block, we establish an optimal model whose objective function is net present value (NPV) profit maximum, whose constrain conditions include investment, reserve/production ratio, production and some equality constraints under the mode of sustainable development. It can be solved by genetic algorithms. The result of case study shows that this optimal investment of oilfield development has multi-stage investment structure under given conditions; the model can provide scientific basic theory for oil companies to make a long-term strategic program and investment plan in oil exploration and development, may decrease the subjective blindness in the investment and bring about a reasonable and orderly exploration and development of oil resources.

High-order rogue wave solutions for the coupled nonlinear Schrödinger equations-II

We study on dynamics of high-order rogue wave in two-component coupled nonlinear Schrödinger equations. Based on the generalized Darboux transformation and formal series method, we obtain the high-order rogue wave solution without the special limitation on the wave vectors. As an application, we exhibit the first, second-order rogue wave solutions and the superposition of them by computer plotting. We find the distribution patterns for vector rogue waves are much more abundant than the ones for scalar rogue waves, and also different from the ones obtained with the constrain conditions on background fields. The results further enrich and deepen our realization on rogue wave excitation dynamics in such diverse fields as Bose-Einstein condensates, nonlinear fibers, and superfluids.

SU‐E‐P‐53: A Plan Quality Comparison for Volumetric‐Modulated Arc Therapy by Different Maximum Delivery Time Setting for Cervical and Upper Thoracic Esophageal Cancer

Purpose:To evaluate and compare the treatment plan quality of volumetric modulated arc therapy (VMAT) plans using different constrain conditions of delivery time for cervical and upper thoracic esophageal cancer.Methods:In this retrospective study, single‐arc VMAT plans were generated with the Oncentra 4.3v system for twenty cervical and upper thoracic esophageal cancer cases. The maximum delivery time were set systematically various as 80s, 110s and 150s. Planning objectives were to deliver 60 Gy in 30 fractions to 95% of PTV, with maximum doses of spinal cord <45 Gy, V5Gy<50%, V10Gy<40%, V20Gy<25% and V30Gy<20% to the lung tissue. All of the three groups of VMAT plans were clinical acceptable. For plan evaluation statistics, PTVDmax, PTVDmin, PTVDmean, PTVD100∼D2, PTVV110∼V90, CordDmax, CordD2, CORDD40, LungDmean, LungV5∼V40 were analyzed and compared by SPSS 20.0.Results:The dose distribution quality of plans generated by different maximum delivery time settings was assessed by anova and non‐parametric tests. No significant differences were found for target and OAR parameters except for the hight dose volume of PTV. The maximum dose (p = 0.034) and D2% (p = 0.030) of PTV in plans with 80s setting were detected significant lower than other plans by anova analysis. And for the maximum dose (p = 0.039) of PTV, it was showed the same results by non‐parametric tests.Conclusion:Considering of the quality of VMAT plans and the treatment time, 80s as the initial parameters of the maximum delivery time would be a better choice than 110s and 150s for cervical and upper esophageal cancer.

A duality of timescales: Short-lived ultrahigh temperature metamorphism preserving a long-lived monazite growth history in the Grenvillian Musgrave–Albany–Fraser Orogen

In situ LA–ICP–MS U–Pb monazite geochronology from the eastern Musgrave Inlier, central Australia, suggests that high-T, suprasolidus conditions were maintained for >70Myr during the Grenvillian (c. 1220–1140Ma). Calculated phase equilibria modelling constrain peak metamorphic conditions to ∼900°C at 6.0–6.5kbar. Collectively, the P–T–t conditions reflect that high-T, low–P metamorphism was contemporaneous with similarly thermally extreme metamorphism in the west and central Musgrave Inlier, and therefore that regionally high geothermal gradients (140–150°C/kbar) prevailed across the entire terrane. However, despite an apparently long-lived history of monazite growth, the results of this study also find evidence for arguably shorter-lived, high-T to ultrahigh temperature metamorphism. Conceivably, the preservation of high-T major element compositions and relict Y+REE growth profiles in small (<500μm) garnet grains suggest that the rocks cooled relatively rapidly to sub-diffusive temperatures. At least initially the peak to retrograde P–T path was also isobaric, or experienced a slight increase in pressure. Grenvillian-aged metamorphism in the eastern Musgrave Inlier accordingly appears to also record the effects of a transient thermal anomaly. This likely developed in response to magmatic-loading and the advection of heat from syn-metamorphic magmatic rocks of the Pitjantjatjara Supersuite, which were emplaced at mid-lower crustal depths, within a longer-lived system characterised by deep-seated, mantle-driven regional metamorphism.

Petrography and composition of Martian regolith breccia meteorite Northwest Africa 7475

AbstractThe Northwest Africa (NWA) 7475 meteorite is one of the several stones of paired regolith breccias from Mars based on petrography, oxygen isotope, mineral compositions, and bulk rock compositions. Its inventory of lithic clasts is dominated by vitrophyre impact melts that were emplaced while they were still molten. Other clast types include crystallized impact melt rocks, evolved plutonic rocks, possible basalts, contact metamorphosed rocks, and siltstones. Impact spherules and vitrophyre shards record airborne transport, and accreted dust rims were sintered on most clasts, presumably during residence in an ejecta plume. The clast assemblage records at least three impact events, one that formed an impact melt sheet on Mars ≤4.4 Ga ago, a second that assembledNWA7475 from impactites associated with the impact melt sheet at 1.7–1.4 Ga, and a third that launchedNWA7475 from Mars ~5 Ma ago. Mildly shocked pyroxene and plagioclase constrain shock metamorphic conditions during launch to &gt;5 and &lt;15 GPa. The mild postshock‐heating that resulted from these shock pressures would have been insufficient to sterilize this water‐bearing lithology during launch. Magnetite, maghemite, and pyrite are likely products of secondary alteration on Mars. Textural relationships suggest that calcium‐carbonate and goethite are probably of terrestrial origin, yet trace element chemistry indicates relatively low terrestrial alteration. Comparison of Mars Odyssey gamma‐ray spectrometer data with the Fe and Th abundances ofNWA7475 points to a provenance in the ancient southern highlands of Mars. Gratteri crater, with an age of ~5 Ma and an apparent diameter of 6.9 km, marks one possible launch site ofNWA7475.

Design and Reuse of Freeform Features on Mesh Surface

To solve the difficulty of reusing complex freeform features on mesh surface,a detail-preserving method is proposed. By means of differential geometry information contained in Laplacian coordinates,such as curvature,normal and so on,put forward a new method to parameterize the boundary loop of features,which is based on differential coordinates. The method of parameterization based on differential coordinates can preserve the length,curvature and the shape of features' boundary curve,which can reduce the deformation of the boundary curve mapped onto the target mesh. The target mesh is parameterized by Geodesic Polar Coordinates method. The boundary curve of features is mapped onto target mesh by the principle of common parameter coordinates. Thus the boundary constraint conditions including position constraint conditions and normal constrain conditions,which are used as the constrain conditions of mesh deformation; can get from the mapped boundary loop. Finally,the feature is deformed to match the target mesh using Laplacian deformation which combines with linear rotation-invariant coordinates. The algorithm avoids parameterizing the reuse features directly,which makes it easy to work with the complex features,and unrelated with the number of feature genus. The results show that the proposed method is robust,effective and can be used to clone the complex features.

Variable crustal thickness beneath Thwaites Glacier revealed from airborne gravimetry, possible implications for geothermal heat flux in West Antarctica

Thwaites Glacier has one of the largest glacial catchments in West Antarctica. The future stability of Thwaites Glacier's catchment is of great concern, as this part of the West Antarctic Ice Sheet has recently been hypothesized to already be en route towards collapse. Although an oceanic trigger is thought to be responsible for current change at the grounding line of Thwaites Glacier, in order to determine the effects of this coastal change further in the interior of the West Antarctic Ice Sheet it is essential to also better constrain basal conditions that control the dynamics of fast glacial flow within the catchment itself. One major contributor to fast glacial flow is the presence of subglacial water, the production of which is a result of both glaciological shear heating and geothermal heat flux. The primary goal of our study is to investigate the crustal thickness beneath Thwaites Glacier, which is an important contributor to regional-scale geothermal heat flux patterns. Crustal structure is an indicator of past tectonic events and hence provides a geophysical proxy for the thermal status of the crust and mantle. Terrain-corrected Bouguer gravity disturbances are used here to estimate depths to the Moho and mid-crustal boundary. The thin continental crust we reveal beneath Thwaites Glacier supports the hypothesis that the West Antarctic Rift System underlies the region and is expressed topographically as the Byrd Subglacial Basin. This rifted crust is of similar thickness to that calculated from airborne gravity data beneath neighboring Pine Island Glacier, and is more extended than crust in the adjacent Siple Coast sector of the Ross Sea Embayment. A zone of thinner crust is also identified near the area's subaerial volcanoes lending support to a recent interpretation predicting that this part of Marie Byrd Land is a major volcanic dome, likely within the West Antarctic Rift System itself. Near-zero Bouguer gravity disturbances for the subglacial highlands and subaerial volcanoes indicate the absence of supporting crustal roots, suggesting either (1) thermal support from a warm lithosphere or alternatively, and arguably less likely; (2) flexural support of the topography by a cool and rigid lithosphere, or (3) Pratt-like compensation. Although forward modeling of gravity data is non-unique in respect to these alternative possibilities, we prefer the hypothesis that Marie Byrd Land volcanoes are thermally-supported by warmer upper mantle. The presence of such inferred warm upper mantle also suggests regionally elevated geothermal heat flux in this sector of the West Antarctic Rift System and consequently the potential for enhanced meltwater production beneath parts of Thwaites Glacier itself. Our new crustal thickness estimates and geothermal heat flux inferences in the Thwaites Glacier region are significant both for studies of the structure of the broader West Antarctic Rift System and for assessments of geological influences on West Antarctic Ice Sheet dynamics and glacial isostatic adjustment models.

Modeling Approach for Fiber Placement Routes on Complex Surface

According to the characteristics of a curve on the surface, the correlation between the placement feasibility for fiber tow and the surface shape of a composite component, width of the fiber tows is analyzed. The placement process route under the condition of fiber tow ultimate deformation is calculated. In addition, based on fiber loading orientation in the designed placement layers, the best mechanical route is calculated. Through the given proportionality coefficient of geodesic arc radii under the constrain conditions of the mechanics and fiber tow deformability on the present route point, a simple modeling approach is proposed to obtain the actual model of the route with the goal of satisfying the best mechanical route orientation . Take the placement of a free form surface as an example to verify the approach, with the result of indicating its reasonableness.

应用遗传算法优化设计机翼复合材料蜂窝夹层结构蒙皮

To improve the strength of composite wing skin of a Unmanned Aerial Vehicle(UAV), the stacking sequence of honeycomb sandwich structure wing skin was designed optimally by a genetic algorithm. According to the design variables' discrete characteristics of the composite, the genetic algorithm based on an integral code strategy was presented. In consideration of the Tsai-Wu criterion, the fitness function was proposed and the constrain conditions were given by the stacking sequence principle of composite laminate layout. Then, the optimized stacking sequence scheme for skin composite structure was obtained by optimization design. Finally, the rationality of the composite laminate layout was verified by finite element analysis and static experiments. The experimental results show that the maximum deformations of the left and right wing tips are 116.02 mm and 105.36 mm, respectively, which meet the requirements that the best deformation is less than 180 mm. Ultrasonic inspection was performed and no damage is detected, which means that the wing structure meets the demands of engineering applications. An UAV with the composite wing skin was flown out successfully, and it verifies the feasibility of proposed design.

Optimized Analysis of the Hollow Floor Based on the Niche Genetic Algorithms

Nowadays, the hollow floor is widely used due to its excellent mechanical property and economic benefit.However, its related specification is absence of evaluation in geometric parameters. The optimized analysis aimed at the hollow floor under vertical load, the total cost of the hollow floor is considered as a objective function, the maximum deflection and the threshold value of the geometric parameters are considered as constrain conditions. The program, which introduces the section design and compiled by the python script, based on the niche genetic algorithms is used to analyze the optimization of a hollow floor. Comparing to the global optimal solution, the program achieves good results. It indicates that the niche genetic algorithms is efficient and suited for the optimization analysis of hollow floor. The above mentioned conclusions will be conducive to engineering design and further research in this field.

Effect of Slenderness Ratio on Inelastic Buckling and Residual Strength of H-Section Steel Column Member

This study presents the effect of slenderness ratio on inelastic buckling behavior and residual strength of H-section steel column member under axial compression loading. Both end pinned H-section steel column constraining rotation on the weak and strong axis was studied. When column members subjected to unexpected compression load (other than design load) will buckle if the applied load exceeds the critical load that induces buckling. To evaluate the effect of slenderness ratio and the influence of constraining rotation in different axis on the structural behavior of H-section steel column member, explicit nonlinear FEM analysis were carried out with reasonable accuracy. To verify the nonlinear finite element analysis, compression test was conducted and both inelastic deformation and the relationship between load-displacement curves were compared. The cumulative energy curve calculated from the load-displacement relationship curve has also been compared and satisfactory result was obtained. From the analysis result the part total energy (the total energy absorbed by the flanges and web) for the two constrain conditions was presented. Furthermore, based on the deflection theory, the relationship between load and displacement was also proposed.

Topology Optimization in Support of Spaceborne Device Based on Variable Density Method

Support is not load bearing components, but also carrier of other component. To reduce the valid load, mass of the support should be low down under the condition of enough stiffness and strength. Topology optimization is employed here to solve the problem. The finite model must be built up according to the basic structure of analysis object in topology optimization. The supports are typical box-style part with thin-wall. Thus, solid model is adopted in ANSYS, and the element shell93 is employed here. Definition of optimization function based on linear-static analysis was employed here. Take maximum flexibility as the constrain conditions of the structure. And the optimality criterion (OC) method was adapted to the problem due to it is suitable for the problem which target is volume. Define the base plate, face and back of the support as the topology area separately. Main part of support is optimization with the variable density method. The results before and after the optimization are compared. When the topology form is unknown, the best topology relation of the structure in the initiate design stage of the whole product has very important meanings.

Optimization analysis on parameters of multi-dimensional earthquake isolation and mitigation device based on genetic algorithm

Parameter optimization analysis on the multi-dimensional earthquake isolation and mitigation device (MEIMD) installed in reticulated structures is carried out in this study. First, optimization parameters and constrain conditions are determined in accordance with the characteristics of MEIMD, and an object function is derived from the energy equation. Then, the genetic algorithm is used to realize parameter optimization of the MEIMD added in a cylindrical reticulated shell. Finally, in order to verify the effectiveness of the proposed optimization method, dynamic responses of structures without devices, with devices possessing random and optimal parameters are compared, and the sensitivity to the earthquake excitations of the optimization method is studied. It can be concluded that dynamic responses of the structure decrease obviously when adding the MEIMD, and a better seismic reduction effect can be reached when the MEIMD is designed optimally in accordance with the optimization method, and different earthquake excitations have slight influence on the optimization results.

NOVEL IN-LINE MICROSTRIP COUPLED-LINE BANDSTOP FILTER WITH SHARP SKIRT SELECTIVITY

This paper presents a novel design approach to design in- line microstrip bandstop fllter with accurate design theory and sharp skirt selectivity. This kind of bandstop fllter is based on a simple coupled-line structure, indicating compact and ∞exible circuit layout for microstrip implementation. For a single-section bandstop fllter, the scattering parameters and their constrain conditions are achieved, which provides an efiective design guide for multi-section bandstop fllters. Theoretical analysis indicates that the even-mode and odd- mode characteristic impedances can be easily used to determine the desired bandstop performance while the total circuit layout keeps very compact. For demonstration, seven numerical examples are designed, calculated, and compared. Finally, both experimental and simulation results of a two-section two-cell microstrip bandstop fllter operating at 1GHz are presented to verify the theoretical predications.

Design on Ultra Wide Band Pulse Waveform

Abstract It is found that design on Pulse signal waveform plays an important role in the Ultra Wide Band (UWB) communication system. Since design on ordinary pulse waveform can not take into account the constrain conditions of UWB both in time domain and frequency domain, there is poor application in practice. Therefore, UWB pulse transmitting circuit is designed based on analysis of ordinary Gaussian pulse circuit. Firstly, ordinary Gaussian pulse circuit is improved by adding attenuation network and high-pass filter; then main parameters of pulse transmitting circuit are optimized by using particle swarm optimization (PSO) algorithm so that output waveform can meet standard of UWB waveform design. Simulation experiment and interference test show that various performance indexes of pulse waveform meet technical requirements of UWB system.

Dynamic Characteristics Analysis for Fluid-Solid Coupling of Vertical Lifting Pipe in Transporting Coarse Particles

Fluid-solid coupling dynamic characteristics analysis of vertical cantilever lifting pipe in transporting coarse solid particles was conducted by adopting ADINA. Firstly, finite element models of pipe and fluid were built, which was solved by using ADINA/FSI module. Secondly dynamic characteristics of pipe vibration for different run-time, constrain conditions, volume concentration and transporting velocities were studied. Thirdly the stress and displacement characteristics were discussed under above conditions. The results were shown that stress and displacement will increase with transporting concentration and velocity rising; the shorter run-up time is, the bigger stress and displacement will be; stress and displacement of lifting pipe supportive anchor in weak constrain were greater than that in fixed connect condition. Analysis results have certain directive significance in future structure design, check, reducing vibration study for lifting pipeline in the ocean mining.

The FOPS Design of Wheel Loader Cabin Based on Topology Optimization

Abstract. It is difficult to seek an optimization design for the falling object protective structure (FOPS) of wheel loader cab. Focusing on this problem, we discuss the topology optimization with SIMP theory under impact condition and the designing parameters, response function and constrain conditions are confirmed. The proposed method is applied to wheel loader cab to get a topology structure. The numerical analysis indicate that the optimized design of wheel loader cab has light weight and can provide sufficient protect for the operator.

Improved Genetic Algorithm of Vehicle Routing Problems with Time Window for Military Logistic Distribution

By changing the constrain conditions of delivery time windows and vehicle capacities to objective function, A vehicle scheduling model was built up based on minimum length of total transportation distance, which included penalty function terms of time window and vehicle capacity constrains, and the model characteristics and application prospects was analyzed. A improved Genetic Algorithm program was put forward to solve the model, in which a chromosome coding suitable to describe delivery routes was designed, a suitable-degree function was proposed, and a reproduction operator, a crossover operator and a mutation operator were constructed. An example was given to demonstrate feasibility of the algorithm. The study indicates that the Algorithm has higher algorithm efficiency and can effectively solve vehicle scheduling problems of military distribution centers.

The Presence of Carbonic-Dominant Volatiles during the Crystallization of Sulfide-Bearing Mafic Pegmatites in the North Roby Zone, Lac des Iles Complex, Ontario

Mafic pegmatites in the platinum-group element (PGE)-mineralized Roby zone, Lac des Iles Complex, northwest Ontario, Canada, comprise dikes, veins, and irregular pods of coarse-grained magnesiohornblende, pyroxene, and labradorite-andesine with minor biotite, apatite, Fe-Ti oxides and intercumulus quartz that grades into massive quartz or graphic quartz-base metal sulfide-vysotskite [Pd, Ni(S)] intergrowth at their cores. Quartz, apatite, and magnesiohornblende host primary and secondary assemblages of one- or two-phase carbonic fluid (CO 2 ± up to ~10% CH 4 ± minor H 2 O, N 2 ) inclusions that contain ore metals (Ni, Cu, Pd, Bi, Te, Fe). Rare trails of late-stage, high-salinity, aqueous fluid inclusions are secondary in origin and, therefore, unrelated to the crystallization of the pegmatites. Assemblages of primary carbonic fluid inclusions show considerable variation in mode and temperature of homogenization, reflecting large fluctuations in confining pressure at the time of quartz crystallization of as much as ~1 kbar (in single quartz crystals) and ~2.8 kbars (all data). Independent thermobarometric methods constrain conditions for the following two stages of pegmatite formation (and carbonic fluid entrapment): (1) the crystallization of magnesiohornblende-plagioclase intergrowth at T ~650° to 850°C, and P ~1 to 3 kbars; and (2) the crystallization of quartz at T ~535° to 650°C, and P ~0.4 to 3.2 kbars, setting the maximum depth of emplacement of the Lac des Iles Complex North Roby zone magma at 10 to 12 km. The results indicate that aqueous-dominant volatile phases were absent during the crystallization of pegmatitic gabbroic rocks at the Lac des Iles Complex and that water-poor, carbonic fluid entrapment persisted to well below solidus conditions. A role played by carbonic fluid as a potential transport medium for ligands involved in the precipitation and remobilization of the PGE and base metals is strongly suggested and warrants further investigation.