Effective Width Research Articles

Compressive behavior of novel cold-formed steel built-up closed L-shaped section columns

This paper proposes a novel type of cold-formed steel (CFS) built-up closed L-shaped section column (CSBC-L). The CSBC-L is a part of the novel special built-up column prefabricated modularized mid-rise CFS structural system (SPMM-CFS), and it can be used to compose the corner-column modulus. The CSBC-L can install sheathing walls in two crossed directions without any other connecting components, and it exhibits large torsional stiffness and inertia moment. This paper conducted experimental investigations on the compressive behavior of CSBC-L with different configurations. Totally 18 test specimens with different plate thicknesses, web heights and screw spacings were designed and tested. The results show that the ultimate strength of CSBC-L can be effectively improved with increasing the web height and plate thickness. Finite element (FE) models were developed for the test specimens, and the failure modes as well as the nonlinear load‒displacement curves were simulated and validated. Finally, the effective width method (EWM) and direct strength method (DSM) are used to predict the ultimate strength of the CSBC-L specimens in AISI S100-16 and EN 1993-1-3. It is found that the DSM is more accurate to predict the axial compressive ultimate strength, and most of the errors are less than 10%.

Design of birch plywood as gusset plates in timber-timber uniaxial tension connections: Influence of fastener pattern, face grain orientation, and discussions based on the Whitmore effective width theory

This study reveals timber-timber composite joints consisting of glulam pieces and birch plywood plates with three different load-to-face grain angles. Utilizing a similar number of fasteners and arranging the fastener array from narrow to wide, uniaxial tension specimens were manufactured with four different fastener patterns. The thickness of birch plywood was intentionally under-designed so that the failure modes for all connections were net tension failure of birch plywood plates. Thereafter, the influence of the fastener pattern and face grain orientation on the load-bearing capacity and stiffness of the investigated composite joints was studied. The load capacity and nominal strength generally increased when the nail patterns varied from narrow to wide. This observation was associated with the Whitmore effective width theory (load spread angle) in steel gusset plate design. Moreover, to derive valid analytical methods to predict the net-tension capacity of birch plywood plates, the classic spread angle model that assumes rectangular stress blocks and the modified spread angle model that considers the summation of stresses from each fastener row were discussed. Both models were adopted to predict the net tension capacity of investigated specimens at 0°. In addition, the stiffness of joints was measured and compared with slip modulus formulas in Eurocode 5. The measured local stiffness values were found to be independent of the fastener pattern and load-face grain angles. The analytical slip modulus assuming the case without predrilling exhibited a satisfactory prediction, while formulas assuming the case with predrilling tend to give overestimations.

Identification of the tip mass parameters in a beam-tip mass system using response surface methodology

Abstract In this study, a response surface based approach is introduced to determine the physical parameters of the tip mass of a beam – tip mass system, such as mass, mass moment of inertia and coordinates of the centre of gravity with respect to the beam end point. To this end, first, a difference function was formulated based on the differences between the peak frequencies and peak amplitudes of the experimental and analytical frequency response functions. Later, observation points were established in the design space using orthogonal arrays, and a response surface was developed using the difference function values at these points. Next, the tip mass parameters were determined by minimizing the response surface with genetic algorithm and particle swarm optimization as well as fmincon, a gradient-based solver of the Matlab program. For comparison purposes, those parameters were obtained by also direct minimization of the difference function with the same algorithms. It was concluded that the tip mass parameters were successfully determined within reasonable error limits by the response surface method with less computational burden. Finally, the effect of design space width on the response surface quality is demonstrated numerically.

A Case Study on the Evacuation of People during a Fire in the Workshop of a Large Factory

A workshop, as a crowded place, is quite easy to cause serious casualties and economic losses once there is a fire. In this paper, Pathfinder software was used to simulate fire emergency evacuation in a workshop of a large factory with building structural symmetry. According to the simulation results, several obstacles to the evacuation were discovered and further analyzed. The results showed that the main factors affecting the evacuation were the width of exits, the distribution of occupants and the effective evacuation width of stairs. Among them, only changing the width of exits had little influence on shortening evacuation time. While changing the effective evacuation width of stairs could greatly relieve the evacuation pressure, every increase of 0.5 m in the width of the staircase could shorten the evacuation time by 30.0 s. Meanwhile, the larger the number of people in high-rise buildings, the longer the evacuation time was. Therefore, the means of restricting people from entering the high-rise buildings in batches could be used to prevent personnel from being evacuated in time when a fire incident occurs.

Effects of pulse width and frequency on evoked responses in electrostimulation: comparison between three muscle groups

Effects of pulse width and frequency on evoked responses in electrostimulation: comparison between three muscle groups

Discovery and timing of pulsar J2016+3711 in supernova remnant CTB 87 with FAST

ABSTRACT We report on our discovery of the radio pulsar, PSR J2016+3711, in supernova remnant (SNR) CTB 87, with a ∼10.8σ significance of pulses, which confirms the compact nature of the X-ray point source in CTB 87. It is the first pulsar discovered in SNRs using Five-hundred-meter Aperture Spherical radio Telescope (FAST). Its integrated radio pulse profile can be well described by a single component, with a width at 50 per cent of the peak flux density of about 28.1○ and an effective width of about 32.2○. The mean flux density at 1.25 GHz is estimated to be about 15.5 $\mu$Jy. Combined with the non-detection of the radio pulse at lower frequencies, the radio spectral index of the pulsar is constrained to be ≲2.3. We also present the timing solution based on 28 follow-up FAST observations. Our results reveal a period of 50.81 ms, period derivative of 7.2 × 10−14 s s−1, and dispersion measure of 428 pc cm−3. The strength of the equatorial surface magnetic dipole magnetic field is inferred to be about 1.9 × 1012 G. Using the ephemeris obtained from the radio observations, we searched Fermi-LAT data for gamma-ray pulsations but detected no pulsed signal. We also searched for radio pulses with FAST towards the X-ray counterpart of the gamma-ray binary HESS J1832−093 proximate to SNR G22.7−00.2 but found no signal.

Relationship between chain axial resistance and confining stress for South China Sea carbonate sand: an element test

For mooring systems, the relationship between chain axial resistance and confining stress affects the tension transfer of embedded mooring chain, and an effective width parameter Et was adopted to reflect the complex geometry of the chain. However, the relationship in carbonate sand is fully understood. Designed as an element test, monotonic and cyclic loading tests were conducted to investigate the variation of chain axial resistance with confining stress under different conditions in South China Sea carbonate sand. Peak effective width parameter and secant coefficient were particularly analyzed to describe the gradual mobilization. The results show that the Et value in South China Sea carbonate sand has a mean increase of 15% compared with Pingtan quartz sand, which makes the chain harder to pull into the carbonate sand. The irregular particle shape may contribute to the higher axial resistance. In cyclic tests, the peak post-cyclic Et-m is larger than that of monotonic test under lower confining stress but is smaller under higher stress. This paper provides some references to chain profile prediction in the carbonate sand.

Numerical Study on Effects of Heights and Widths on Airflow and Pollutant Dispersion around a Building

Studying the mechanism of pollutant transport around an isolated building is essential to address the environmental issue of air pollution around buildings and to understand the intricate process of pollutant dispersion in urban environments. In this paper, an effective numerical approach is used to study the effects of building heights and widths on airflow and pollutant dispersion around an isolated building. The source of pollutants is behind the building. The pollutant is confined to the lower areas as a result of small vortices behind the low-rise buildings, and transported to the wake area. Whereas high-rise buildings make the pollutant move to an upper region. At the pedestrian level, the wake area of the lower building stores more pollution. Therefore, the environment around the low-rise buildings may be more hazardous. The concentration of pollutants is greater at higher altitudes around wider buildings. Pollutants are transferred to the sides of wider buildings at the pedestrian level, leading to lower concentrations in the wake-central area. A wider building poses a greater lateral dangerous-area, while a narrower building results in a longer central wake area that is hazardous.

Comparison of edge effects from well pads and industrial roads on mixed upland boreal forest vegetation in Alberta

AbstractThe industrial footprint of oil and gas extraction in Alberta, Canada dissects the landscape in a network of linear and polygonal disturbances such as roads and well pads. The changes to biotic and abiotic factors beyond the boundaries of these disturbances into the adjacent ecosystem are called edge effects. A common assumption is that edge effects are proportional to the width of the disturbance, with wider disturbances leading to deeper effects into the forest. The objective of this study is to compare edge effects on plant composition, seed dispersal distance, seed weight, and microclimate across three disturbance types: narrow (< 20 m) and wide (> 20 m) roads, and well pads (> 100 m; 1.9 ha) in upland boreal forests in the oil sands region of north-eastern Alberta. We sampled 1 m2 plots at six distances (0 m, 10 m, 15 m, 25 m, 50 m, and 75 m) along transects running perpendicular from the disturbance edge into the forest. Edge effects for plant communities were contained at the disturbance edge for all disturbance types considered. Understory species richness was lower at the disturbance edge and was dominated by introduced species and species with lighter seeds and with medium-distance dispersal mechanisms. Disturbance edges were characterized as having higher soil moisture content, higher soil temperature, and a thinner organic matter layer compared to the forest interior (> 10 m). With no effect of disturbance width on width of edge effects, our study does not support the assumption that narrower disturbances will necessarily result in narrower edge effects for vegetation and abiotic metrics.

Analysis of interaction between reinforced concrete walls and slabs tested on a shaking table

AbstractAn analysis of the interaction between reinforced concrete walls and slabs tested on the shaking table was performed. The tested structure consisted of four walls connected by three slabs without coupling beams. Although these walls would be typically considered cantilever walls, significant coupling was observed, resulting in considerably different response mechanisms than those observed for typical cantilever walls. As observed in past earthquakes, these unexpected response mechanisms can cause walls' brittle failure. Numerical analyses were performed to study the critical parameters causing the observed response. The response was primarily influenced by the considerable slabs' effective width (EW), significantly affecting the walls' and slabs' strength ratio. Owing to the large EW, the slabs' strength was threefold larger than the standard value typically considered in the design. The slabs provided considerable coupling (CL) of walls, significantly increasing the total stiffness and the total base shear (BS) of the structure compared to standard cantilever walls. Owing to the increased BS and redistribution of the demand between wall piers caused by large CL, the maximum shear forces in the piers were more than doubled than that observed in the cantilever walls. The compression axial forces in piers were also considerably increased, causing the buckling of the longitudinal reinforcement.

Indirect confirmation and theoretical application of plasma shock−cavitation principle of pulsed laser shock

The coupling strengthening principle of the double physical effect of plasma shock−cavitation was proposed, and the rationality of the cavitation effect in pulsed laser shock treatment under liquid−confined conditions needs to be confirmed urgently. The XRD testing method and 304 stainless steel, which is easy to obtain diffraction peaks, were selected to quantitatively detect and characterize the residual stress distribution in the action area of a single pulse laser beam. The test results and literature analysis show that the different process conditions of laser shock processing bring about different strength matching of the two stress effects of plasma shock and cavitation, and the main source of stress effect of femtosecond laser shock without coating is the cavitation effect. The actual effects of the laser pulse width and other process parameters such as the absorption layer and the constraint layer affect or determine the material modification principle of the pulsed laser surface treatment.

PENGGUNAAN WINDOW WIDTH DAN WINDOW LEVEL PADA PEMERIKSAAN COMPUTED TOMOGRAFY SCANNER THORAX DENGAN KLINIS ANEURISMA AORTA DI RUMAH SAKIT AL ISLAM BANDUNG

Setting the parameters of Window Width and Window Level on CT Scan Thorax examination using contrast media can produce a good image of the lungs and aorta. The purpose of this study is to find out the right window setting so as to produce a good image in the case of Aortic Aneurysm. This type of research is descriptive qualitative with a case study approach. 
 The results showed that the effect of window width and Window Level parameter settings on the lung window and mediastinum window provided optimal image quality results of abnormalities in the lungs and surrounding anatomical structures.

Adsorption Characteristics of CO2/CH4/H2S Mixtures in Calcite Nanopores with the Implications for CO2 Sequestration

Summary Injecting CO2 into reservoirs for storage and enhanced oil recovery (EOR) is a practical and cost-effective strategy for reducing carbon emissions. Commonly, CO2-rich industrial waste gas is used as the CO2 source, whereas contaminants such as H2S may severely impact carbon storage and EOR via competitive adsorption. Hence, the adsorption behavior of CH4, CO2, and H2S in calcite (CaCO3) micropores and the impact of H2S on CO2 sequestration and methane recovery are specifically investigated. The Grand Canonical Monte Carlo (GCMC) simulations were applied to study the adsorption characteristics of pure CO2, CH4, and H2S, and their multicomponent mixtures were also investigated in CaCO3 nanopores to reveal the impact of H2S on CO2 storage. The effects of pressure (0–20 MPa), temperature (293.15–383.15 K), pore width, buried depth, and gas mole fraction on the adsorption behaviors are simulated. Molecular dynamics (MD) simulations were performed to explore the diffusion characteristics of the three gases and their mixes. The amount of adsorbed CH4, CO2, and H2S enhances with rising pressure and declines with rising temperature. The order of adsorption quantity in CaCO3 nanopores is H2S > CO2 > CH4 based on the adsorption isotherm. At 10 MPa and 323.15 K, the interaction energies of CaCO3 with CO2, H2S, and CH4 are −2166.40 kcal/mol, −2076.93 kcal/mol, and −174.57 kcal/mol, respectively, which implies that the order of adsorption strength between the three gases and CaCO3 is CO2 > H2S > CH4. The CH4-CaCO3 and H2S-CaCO3 interaction energies are determined by van der Waals energy, whereas electrostatic energy predominates in the CO2-CaCO3 system. The adsorption loading of CH4 and CO2 are lowered by approximately 59.47% and 24.82% when the mole fraction of H2S is 20% at 323.15 K, reflecting the weakening of CH4 and CO2 adsorption by H2S due to competitive adsorption. The diffusivities of three pure gases in CaCO3 nanopore are listed in the following order: CH4 > H2S ≈ CO2. The presence of H2S in the ternary mixtures will limit diffusion and outflow of the system and each single gas, with CH4 being the gas most affected by H2S. Concerning carbon storage in CaCO3 nanopores, the CO2/CH4 binary mixture is suitable for burial in shallower formations (around 1000 m) to maximize the storage amount, while the CO2/CH4/H2S ternary mixture should be buried as deep as possible to minimize the adverse effects of H2S. The effects of H2S on CO2 sequestration and CH4 recovery in CaCO3 nanopores are clarified, which provides theoretical assistance for CO2 storage and EOR projects in carbonate formation.

Pedestrian level of service for sidewalks in Tangier City

The pedestrian level of service (PLOS) is a measure that quantifies walkway comfort levels. PLOS defined into six categories (A, B, C, D, E, and F) each level defines the range of values, for example, a good level (best traffic condition) is defined with the letter A until reaching the worst level, F (high congestion). This article aims to define the PLOS on sidewalks considering walking conditions in Tangier City (Morocco). Sidewalks are analyzed using video recording in the urban center of Tangier City. The collected data are pedestrian flow and effective sidewalk width. Each level contains a range of values that corresponds to the pedestrian flow that defines the level of service. Clustering techniques are used to identify the threshold of each level using a self-organizing map (SOM). The results are different from those obtained with other methods because pedestrian traffic differs from country to country.

Wave absorbing properties of Ni Nanoparticle/CNT composite film fabricated by AAO/CNTs electrode

An effective wave absorbing Nano-Ni/carbon nanotubes (CNTs) composite film was developed by electrodeposition using an anodic aluminum oxide (AAO)/CNTs electrode. Scanning electron microscopy images confirmed the uniform dispersion of Ni nano-particles within the CNTs, and the particle diameter increasing from 20 nm to 100 nm as the deposition time increased. XRD test results revealed that the crystal phase of the Ni nano-particles remained unchanged during different deposition time, exhibiting a Face Center Cubic (fcc) structure. The microwave electromagnetic properties of the film were evaluated using a vector network analyzer, and the return loss curve demonstrated that the Ni nano-particles/CNTs composite exhibited exceptional wave absorption capabilities. The composite film showed an effective absorption width of 13 GHz (4–17 GHz) and achieved a minimum reflection loss (RL) of −17 dB at 14 GHz.

Leaky-wave antenna on substrate-integrated waveguide with radiation pattern controlled by DC voltage

Abstract This paper presents the application of a substrate-integrated waveguide (SIW) for the design of a leaky-wave antenna (LWA). The antenna radiates through a wide slot in the top wall of the SIW structure in the forward direction. The effective width of the slot is varied by changing capacitances of two arrays of varactors connected between slot edges and inserted conducting strips. The radiation pattern of the antenna is by this way controlled by DC bias, which sets the capacitances of varactors. The maximum radiation direction in elevation can be varied within 35° by changing the DC bias from 2 to 12 V. This elevation angle is measured from the broad side direction perpendicular to the antenna substrate. The measured antenna characteristics are in accord with those predicted by simulation. The antenna can be simply fabricated by a planar circuit board technology.

Study on the impact of the resonant cavity and lateral acoustic edge reflector for AlSc0.095N-based S0 mode Lamb-wave resonators

In this paper, the impact of the resonant cavity and lateral acoustic edge reflector on the performance of the S0 mode Lamb-wave resonators based on Aluminum nitride film doped with scandium concentration of 9.5 % (AlSc0.095N) were systematically studied. Through the theoretical analysis and experimental verification, we found that the Q value of the resonator can be improved by defining a miniaturized resonant cavity due to the enhanced acoustic reflection effect at the anchor boundary. The effect of lateral reflection boundary width on the spurious modes, Q values, and electromechanical coupling coefficient (k2eff) of the resonators was analyzed. In addition, the k2eff and Q values of the interdigitated transducer (IDT)-IDT resonators are higher than those of the IDT-Floating resonators, due to the larger electromechanical conversion efficiency and smaller interface loss. The experimental results show that the Q and k2eff values of the optimized IDT-Floating and IDT-IDT resonators reach 853, 1.70 % and 1362, 2.69 %, respectively, meanwhile, they have clean spectrums.

Aerothermal performance of cavity tip with flow structure effects in a transonic high-pressure turbine blade

Understanding the mechanisms of leakage flow control and heat load distribution is important in optimizing the structure of cavity tips in gas turbines. This paper investigates the aerothermal performance of cavity tip in a transonic high-pressure turbine stage. By analyzing flow structure, the effects of squealer height, squealer width and gap height on aerothermal performance are explained. It has been found that both the leakage flow and heat load distribution are influenced by the structure of vortices in the cavity. The leakage flow is controlled by the suction-side cavity vortex and the scraping vortex. The heat load distribution relates to the “M-shaped” leakage flow induced by the scraping vortex. The geometric parameters can affect the structure of vortices, which then impacts the aerothermal performance of cavity tip. As the squealer height is 2.5τ0, both the leakage flow rate and average heat transfer coefficient decrease by 0.64 % and 6.6 %, respectively. A multi-objective optimization with a feedforward neural network prediction is conducted to determine the distribution characteristics of optimal design parameters. The optimal values are approximately 2.34 for the expansion ratio, 0.5τ0 for the squealer width and 0.5τ0 for the gap height. The optimal squealer height ranges from 1.5τ0 to 2.5τ0.

On-Chip Modification of Titanium Electrothermal Characteristics by Joule Heating: Application to Terahertz Microbolometer.

This study demonstrates the conversion of metallic titanium (Ti) to titanium oxide just by conducting electrical current through Ti thin film in vacuum and increasing the temperature by Joule heating. This led to the improvement of electrical and thermal properties of a microbolometer. A microbolometer with an integrated Ti thermistor and heater width of 2.7 µm and a length of 50 µm was fabricated for the current study. Constant-voltage stresses were applied to the thermistor wire to observe the effect of the Joule heating on its properties. Thermistor resistance ~14 times the initial resistance was observed owing to the heating. A negative large temperature coefficient of resistance (TCR) of -0.32%/K was also observed owing to the treatment, leading to an improved responsivity of ~4.5 times from devices with untreated Ti thermistors. However, this does not improve the noise equivalent power (NEP), due to the increased flicker noise. Microstructural analyses with transmission electron microscopy (TEM), transmission electron diffraction (TED) and energy dispersive X-ray (EDX) confirm the formation of a titanium oxide (TiOx) semiconducting phase on the Ti phase (~85% purity) deposited initially, further to the heating. Formation of TiOx during annealing could minimize the narrow width effect, which we reported previously in thin metal wires, leading to enhancement of responsivity.

Nonlinear bond-slip model for fiber-reinforced polymer laminates externally bonded to thermally damaged concrete

This paper presents a novel nonlinear local bond-slip model for fiber-reinforced polymer (FRP) laminates externally bonded to thermally damaged concrete substrates. The proposed model is an extension of an existing two-parameter bond-slip model and incorporates two key parameters including interfacial fracture energy ([Formula: see text]) and interfacial brittleness index ([Formula: see text]). To study the variations of [Formula: see text] and [Formula: see text] with different thermal damage levels of the concrete substrate, an extensive experimental database of shear tests on FRP-to-thermally damaged concrete bonded joints was collected from the existing literature. The [Formula: see text] values were calculated from the peak pull loads with proper consideration of the bond length and width effects, while the [Formula: see text] values were obtained by least-squares regression analysis using experimental load-displacement curves or measured strain distributions in the FRP laminates. The results have indicated that the [Formula: see text] values initially exhibit a slight increase accompanied by mild thermal damage of the concrete substrate after exposure to moderately high temperatures; however, these values significantly decrease when the exposure temperature exceeds 300°C. The [Formula: see text] values initially decrease with high-temperature exposure and stabilize at around 50% of the initial values when the temperatures reach around 400°C. Despite the inherent variability in the test database, the proposed temperature-dependent bond-slip model has demonstrated its accuracy, as demonstrated by the comparisons between the theoretical predictions generated by the model and the corresponding shear test results. This interfacial bond-slip model is expected to serve as a constitutive law to characterize the bond behavior between externally bonded FRP laminates and thermally damaged concrete substrate, thus facilitating the practical application of high-performance FRP composites in the repair and strengthening of thermally or fire-damaged RC members.