Slow Loading Research Articles

Design and research of a novel solid oxide fuel cell with thermal energy storage for load tracking

Solid oxide fuel cell (SOFC) is a promising energy conversion device. However, the severe temperature fluctuations and slow load switching caused by huge thermal inertia during load tracking are urgent issues to be solved. In this paper, a novel SOFC system with thermal energy storage (TES) was proposed and studied. The 1D models of fuel cell stack and TES were established based on electrochemical and thermodynamic laws. The output power switch between full load and half load was explored as an example, and the dynamic response of the proposed system and traditional SOFC was compared, which was achieved by step changes in current. The results indicated that the maximum fluctuations in the inlet gas temperature of traditional SOFC stacks under load step-down and step-up conditions were 169.21 K and 95.24 K, respectively. TES could maintain a constant gas temperature at the entrance of fuel cell stack, thereby avoiding severe temperature fluctuations in the stack. The proposed system would significantly reduce the maximum temperature gradient during load switching and half-load operation. In addition, compared to traditional SOFCs, the dynamic response time of the system with TES had been reduced from thousands of seconds to around 300 s, which meant that the load step-down and step-up processes had been shortened by 93.79 % and 80.52 %, respectively. The response time of load step-down was longer than that of step-up, due to heat generation within the fuel cell stack. The output power of the proposed system during half load operation was 0.21 KW higher than traditional system, which meant an increase of 7.75 % in output power. Finally, the ramp current was adopted to solve the problem of fuel definition in step-up condition, and the response time of the power was 41 s longer than the step current.

Development and in functional study of a bi-specific sustained release drug-loaded nano-liposomes for hepatocellular carcinoma.

Lenvatinib (LEN) is a first-line therapy for patients with hepatocellular carcinoma (HCC), but has a larger adverse effect profile. In this study, we developed a liposome with drug-carrying function and magnetic resonance imaging (MRI) imaging function to investigate the targeted drug-carrying function and MRI tracing ability of liposome for HCC. Magnetic nano-liposomes (MNL) with dual targeting function of epithelial cell adhesion molecule (EpCAM) and vimentin and capable of encapsulating LEN drugs were prepared. The characterization performance, drug loading efficiency and cytotoxicity of EpCAM/vimentin-LEN-MNL were tested, and the dual-targeting slow release drug loading function and MRI tracing ability were investigated in cellular and animal models. EpCAM/vimentin-LEN-MNL has a mean particle size of 218.37 ± 5.13nm and a mean potential of 32.86 ± 4.62mV, and is spherical in shape and can be uniformly dispersed in solution. The encapsulation rate was 92.66 ± 0.73% and the drug loading rate was 9.35 ± 0.16%. It has low cytotoxicity, can effectively inhibit HCC cell proliferation and promote HCC cell apoptosis, and has specific targeting function and MRI tracing ability for HCC cells. In this study, an HCC-specific dual-targeted sustained-release drug delivery liposome with dual-targeted recognition and sensitive MRI tracer was successfully prepared, which provides an important scientific basis for maximizing the multiple effects of nano-carriers in tumor diagnosis and treatment.

Efficient segment-update block LMS-Newton algorithm for active control of road noise

For active control of road noise inside a vehicle, many reference signals are required in adaptive control systems, resulting in slow convergence speeds and heavy computational loads. In this paper, a means of reducing the computational complexity of adaptive control algorithms is investigated based on the fast-converging least-mean-squares Newton (LMS-Newton) algorithm. By analyzing the autocorrelation matrix of reference signals filtered by secondary paths, it is found that the dimensions of the autocorrelation matrix of filtered reference signals do not necessarily have to equal the dimensions of the adaptive control filters, and instead the dimensions can be determined from the correlation between reference signals filtered by secondary paths. Then a computationally efficient segment-update block algorithm is proposed that splits adaptive control filters into several segments and the coefficients of each segment are updated independently. Theoretical analysis shows that the proposed segment-update block algorithm has similar convergence speed and noise-reduction performance as the traditional LMS-Newton algorithm when a segment of appropriate length is chosen, but the computational complexity is reduced dramatically because the inverse autocorrelation matrix is replaced by a smaller matrix. The performance of the proposed algorithm is verified through simulation experiments with different recorded road noises and secondary paths, and the results are compared with those of some typical algorithms. The simulation results showed that the proposed algorithm achieved a similar noise-reduction performance with an approximately 8.9-times reduction of computational complexity compared with the traditional LMS-Newton algorithm.

High temperature in situ impact testing of hybrid thermoplastic polyether ether ketone laminates

AbstractIn order to evaluate the severity of thermal degradation on the impact response of carbon (C) and glass (G) fibers reinforced polyether ether ketone laminates, low velocity impact tests have been conducted at a temperature higher than the glass transition temperature (150°C). An instrumented Charpy pendulum (CP) equipped with a heating device was specifically designed to estimate its capability to perform low velocity impact tests at high temperature. The first important effect resulting from temperature increase is a reduction of the impact energy required to induce the barely visible impact damage (BVID), whose role is utmost important regarding the damage tolerance. The second effect is that temperature has also a tremendous influence on the internal damage as there is virtually no delamination at high temperature for impact energies. Finally, compared with the impact behaviors observed with the same laminates impacted with a drop tower and quasi‐static indentation, the impact velocity is about 2.5–3 times as low during CP impacts. As a result, slow loading rates are instrumental in increasing both the dissipated energies and the permanent indentation (PI) values (1.6–2 times as high) that are always higher than the BVID. Ultimately, as higher PI is usually correlated to higher impact damage tolerance.

Micromechanics and damage in slide-ring networks.

We explore the mechanics and damage of slide-ring gels by developing a discrete model for the mechanics of chain-ring polymer systems that accounts for both crosslink motion and internal chain sliding. The proposed framework utilizes an extendable Langevin chain model to describe the constitutive behavior of polymer chains undergoing large deformation and includes a rupture criterion to innately capture damage. Similarly, crosslinked rings are described as large molecules that also store enthalpic energy during deformation and thus have their own rupture criterion. Using this formalism, we show that the realized mode of damage in a slide-ring unit is a function of the loading rate, distribution of segments, and inclusion ratio (number of rings per chain). After analyzing an ensemble of representative units under different loading conditions, we find that failure is driven by damage to crosslinked rings at slow loading rates, but polymer chain scission at fast loading rates. Our results indicate that increasing the strength of the crosslinked rings may improve the toughness of the material.

An Experimental and Theoretical Study on the Tailings Dam with Geotextile Bags

The friction performance and compression properties of geotextile bags under different degrees of consolidation are researched through the slope sliding test, direct shear test, and unconfined compression test in this study. The geotextile bags are made up of geotextile and tailings sands obtained from a construction site of a prototype tailings dam in Yunnan Province. The slope sliding test is considered as an easy method to study the friction performance of geotextile bags with different degrees of consolidation. Through the test, the friction coefficients between the bags were obtained. Given the geotextile bags can withstand the vertical load in practical engineering, the direct shear test is also proposed and conducted. The ultimate bearing capacity of the geotextile bags with different consolidation degrees is studied in the unconfined compression test. The test reveals that the ultimate bearing capacity of geotextile bags, although featured with different moisture contents before the test, stays the same under the condition of slow loading. Finally, a stability analysis method based on the limit equilibrium theory is developed to simulate the stability of the tailings dam using geotextile bags (TDGB). According to the test results, the TDGB has demonstrated an improved stability compared with the general tailings dam.

Dynamics of large-scale bubbling fluidized bed combustion plants for heat and power production

Bubbling fluidized bed combustion (BFBC) plants for combined heat and power (CHP) production have traditionally been dispatched under slow load changes. As the amount of variable renewable electricity increases in energy systems worldwide, knowledge regarding the transient capabilities of the gas and water-steam sides of BFBC plants is required. The aim of this work is to investigate the dynamic performance of large-scale BFBC plants when accounting for both the gas and water-steam sides. To do so, this paper presents a dynamic model of BFB-CHP plants that result from connecting a model of the gas side to a process model of the water-steam side. The plant model output is validated by comparisons with operational data measured in a 130-MWth BFBC plant that produces electricity, district heating (DH) water and steam for industrial clients. The validation shows that the model can satisfactorily describe both multi-load steady-state operation and load transients. The simulation results highlight the fact that the water-steam cycle achieves stabilization more rapidly after changes in the DH line and steam delivered to customers, as compared to changes in the combustor load. The timescales of the plant outputs for different changes have been calculated, with stabilization times ranging from 2 to 15 min for the power production versus 2–25 min characterizing the DH production. Compared to the stabilization times of the gas side, the water-steam side is an order of magnitude slower, thereby limiting the transient operation capabilities of BFB-CHP plants.

Load Time Optimization on React Website using Incremental Static Regeneration with NextJS

There’s a lot of tools that can be used to build or develop a website. Starting from basic HTML CSS and JavaScript to the use of UI Framework such as React, Angular, Vue JS or Svelte But, the use of UI Framework doesn’t come with no cons. UI Framework like React, use virtual DOM, instead of modifying the DOM directly, so when the first time application load, the framework needs to load library to modify the virtual DOM, before the page can load. This can leads to slow first loading time. This paper research performance improvement when using ISR ( Incremental Static Regeneration ) in NextJS

Influence of Fluids on Earthquakes Based on Numerical Modeling

AbstractThe strength and sliding behavior of faults in the crust is largely controlled by friction and effective stress, which is itself modulated by fluid pressure. Most earthquake models assume a fixed pore fluid pressure despite widespread evidence that is varies strongly in time due to changes in permeability. Here we explore how dynamic changes in pore pressure influence the properties of earthquakes in the upper crust. To study this problem we develop a two dimensional model that incorporates slow tectonic loading and fluid pressure generation during the interseismic period with frictional sliding on a thrust fault whose permeability evolves with slip. We find that the presence of relatively modest fluid overpressures tends to reduce coseismic slip, stress drop, maximum sliding velocity, rupture velocity and the earthquake recurrence time compared to models without fluids. Our model produces a wide range of sliding velocities from rapid to slow earthquakes, which occur due to the presence of high pore pressures prior to rupture. The models also show evidence for aftershocks that are driven by fluid transfer along the fault plane after the mainshock. Overall, this study shows that fluids can exert an important influence on earthquakes in the crust, which is mostly due to modulation of the effective stress and variations in permeability, and to a lesser extent to poro‐elastic coupling.

Experimental test and PFC3D simulation of the effect of a hole on the tensile behavior of concrete: A comparative analysis of four different hole shapes

In this article, the effects of porosity and its geometry on tensile features of concrete were investigated, using the Brazilian test and three dimensions PFC model. In the first step, the PFC sample was calibrated by indirect tensile lab outcomes and uniaxial compression test outputs. In the next step, indirect tensile tests were done on the models consisting of various pore shapes. Cylindrical models consisted of internal pores with different shapes such as rectangular, circular, horizontal notch, and vertical notch. The diameter and or the length of these porosity changes in various values, i.e., 10 mm, 20 mm, and 30 mm. Twelve different configurations of samples were prepared by varying the porosity shapes. The mechanical behavior of samples has been provided in form of stress–strain curves at a constant and slow loading rate of 0.05 mm/min for ensuring the static condition based on Newton’s first law. Concurrent with numerical simulation, an experimental test was done on the concrete slabs containing different pores. The outcomes showed that porosity geometry plays an important role in the fracturing pattern. It was found that the porosity geometry has potent consequences on fracturing process stress and the value of the UCS for rocks. Numerical simulation shows that fracture energy decreased by increasing the dimension of the defect. Crack initiation stress was close to final stress in vertical notch configuration while the difference between the final stress and crack initiation stress has a high value for horizontal notch configuration. The sharper the hole tip, the faster the progressive failure occurred.

Dynamic Freewheeling Control for SIDO Buck Converter With Fast Transient Performance, Minimized Cross-Regulation, and High Efficiency

Slow load transient performance, potential cross-regulation, and low efficiency are the major drawbacks for pseudocontinuous conduction mode single-inductor dual-output (SIDO) dc–dc converters. To overcome these drawbacks, this article proposes a voltage-ripple (VR)-based dynamic freewheeling (DF) control technique for hybrid conduction mode (HCM) SIDO buck converter. With the employment of VR controller, the proposed control technique improves the load transient performance significantly. As the fast recovery during load transition, the cross-regulation is minimized. Additionally, due to the DF controller, the freewheel current value automatically updates in each switching period, which can improve the efficiency of the HCM SIDO buck converter, especially under the light load conditions. Finally, the proposed converter has been verified through experimental results. The transient response time on 0.5 A load change takes only 1–2 switching periods. No observable cross- regulation is found and maximum efficiency of 92.03% is achieved. Finally, the experimental waveforms are presented to verify the theoretical research.

Modelling of Synthetic Fibre Rope Mooring for Floating Offshore Wind Turbines

Fibre ropes offer beneficial properties for mooring of floating offshore wind turbines (FOWTs). However, the mooring line’s stiffness is both load-history and load-rate dependent. A quasi-static stiffness is observed for slow loading, with a higher stiffness related to rapid, cyclic loading (dynamic stiffness). Design standards provide different guidelines for how to combine these in the mooring analysis. This paper describes procedures for adapting laboratory test stiffness results to the Syrope and a bi-linear model and investigates the consequence of using the models for load calculations. The Syrope model accounts for the quasi-static and permanent rope elongation, while performing the analyses with the dynamic stiffness. The bi-linear model applies both the quasi-static and dynamic stiffness in the dynamic analyses. Based on fibre rope tests performed by Bridon-Bekaert, a Syrope model and two bi-linear models are adapted to the same fibre rope. Fatigue damage and ultimate loads on the mooring lines of Saitec’s SATH FOWT are calculated. The bi-linear model artificially reduces the tension ranges, particularly if there is a large difference between the quasi-static and dynamic stiffness of the fibre rope. This leads to a longer predicted fatigue lifetime. Differences in the extreme loads are caused by the permanent elongation of the Syrope model. This may be countered if the elongation is known and included in the bi-linear model. Finally, the bi-linear model introduces an amplitude-dependency in the horizontal natural periods.

Preliminary results from push-and-release tests of a base-isolated building in Camerino, Italy

Experimental testing of a two-storey steel braced-frame building structure on a reinforced concrete slab isolated from the foundations resting on a steep slope through a hybrid system (high-damping rubber bearings and low-friction sliding bearings) is presented. The base-isolated building incorporates a permanent push-and-release device capable of displacement amplitudes as those induced by extreme seismic events and allowing the push-and-release tests to be repeated in the future. The tested building as well as its testing set up, whose cost represents a small increment of its construction cost if planned in the early stages of the design process, are presented. Afterwards, preliminary results from quasi-static push tests (slow loading and unloading) and push-and-release dynamic tests (slow loading and subsequent sudden release) are briefly described. Compared to push-and-release tests documented in the past, the activities presented in this article have peculiarities related to the building (typology, size, and foundation geometry), the magnitude of the maximum horizontal displacement achieved (284.6 mm), the possibility to repeat the same tests in the future, producing comprehensive sets of data for the analysis of the behaviour of the hybrid isolation system and superstructure.

Laboratory Simulation of Earthquake-Induced Damage in Lava Dome Rocks

Earthquakes can impart varying degrees of damage and permanent, inelastic strain on materials, potentially resulting in ruptures that may promote hazards such as landslides and other collapse events. However, the accumulation of damage in rocks under the frequency and amplitude of shaking experienced during earthquake events is rarely systematically measured due to technical limitations. Here, we characterize damage evolution during laboratory experiments on a suite of dacitic rocks from Unzen volcano, Japan, to help resolve accumulated damage and landslide susceptibility of lava domes during regional earthquake events. Damage was imparted during slow (time-dependent creep) and fast (stress-oscillation earthquake simulations) uniaxial loading in compression and tension. Damage evolution is approximated from strain during experiments; all samples accumulate strain during earthquake events, but microfracture-dominated samples tend to be more susceptible to damage than vesicle-dominated samples. The orientation of existing fabrics with respect to loading direction dictates the magnitude of strain accumulation under load oscillations. During each “earthquake” experiment of multiple dynamic stress-oscillations, samples accumulate inelastic strain. The strain imparted during each successive event is initially high and then reduces after 5-7 events, except when stressing results in failure. The strain rate during phases of intermittent stressing tends to be higher than prior to them. Understanding the accumulation of damage and the potential for brittle failure of rocks subjected to earthquakes can help define the origin and timing of certain landslides, rockfalls, lava dome collapses, and other failure events.

Research on Lightweighting and Rendering Optimization Techniques for Building Information Models

Traditional Building Information Modeling (BIM) services, using a client-server (C/S) architecture, struggle to adapt to the new demands and changes in the field of architectural informatization. The development of a comprehensive BIM visualization system, which is web-based, requires no installation or downloading, is cross-platform, and facilitates easy sharing, has become a new pathway for BIM advancement. However, when rendering the vast amount of data in BIM three-dimensional scenes on the web, several issues persist, including low transmission efficiency, slow loading speed, laggy screen display, and low rendering frame rates, particularly on mobile devices and terminals with limited hardware performance. Therefore, this paper proposes BIM lightweighting techniques based on geometric data and texture information, as well as a web-based rendering optimization method for three-dimensional models. In terms of BIM lightweighting, more efficient methods and algorithms are employed to simultaneously lighten the geometric data and texture information of the models. For rendering optimization, an efficient view frustum culling algorithm is introduced, along with a design for an adaptive rendering strategy to enhance rendering performance.Through testing the loading efficiency of different scale BIM models before and after optimization was tested on the web. Results show that, while maintaining display accuracy, the average loading time of the optimized models was reduced by 40% compared to the unoptimized models. The average data compression rate reached 45%, and the average memory usage decreased by 32.55%. After stable rendering, the frame rate was close to 60fps.

How does lithospheric viscosity control the temporal patterns of seismicity during an earthquake cycle?

The temporal patterns of regional seismicity, such as acceleration and deceleration patterns of seismic moment release, Benioff strain release, or number of earthquakes over time before a big earthquake or between two big earthquakes, have been observed in various regions. However, the mechanisms or controlling factors to cause these temporal patterns of seismicity have not been fully clarified. In this study, we collect, summarize, and analyze temporal patterns of regional seismicity (acceleration and deceleration patterns) in the world and observe a statistical relation between them and regional lithospheric viscosity values. We also develop and use a three-dimensional viscoelastoplastic finite-element model and an analytical model, to investigate and explain the importance of lithospheric viscosity on temporal patterns of seismicity during an earthquake cycle. We find that viscosity in lower crust and upper mantle can control seismicity acceleration and deceleration patterns during an earthquake cycle: low viscosity tends to cause deceleration pattern because fast postseismic stress accumulation within upper crust due to fast stress relaxation in viscoelastic layers following an earthquake induces frequent occurrence of regional earthquakes at early stage of an earthquake cycle, but on the contrary, high viscosity encourages acceleration pattern with frequent occurrence of regional earthquakes at late stage of an earthquake cycle. Between the low and high viscosity, a transitional viscosity zone roughly ranging from ∼1 × 1019 to ∼1 × 1020 Pa s exists. When average viscosity in lower crust and upper mantle stays in this range, regional seismicity acceleration and deceleration patterns can coexist at similar percentages and it is statistically hard to distinguish which pattern dominates in the region. Regional tectonic loading velocity also has an impact on temporal patterns of seismicity during an earthquake cycle: slow tectonic loading velocity tends to induce seismicity deceleration pattern, but fast tectonic loading velocity encourages seismicity acceleration pattern.

In vitro characterization of immune modulating drug-eluting immunobeads towards transarterial embolization in cancer

Hepatocellular carcinoma (HCC) is an aggressive liver cancer with limited effective treatment options. In this study, we selected TLR agonists imiquimod (IMQ), gardiquimod (GARD), GS-9620 and DSR 6434, and a small molecule checkpoint inhibitor, BMS-202, for characterization of drug loading and release from radiopaque embolic beads (DC Bead LUMI) for potential use in image-guided transarterial embolization (TACE) of HCC. The maximum drug loading capacity and amount of drug released over time were determined by high performance liquid chromatography and compared with the commonly used anthracycline, doxorubicin hydrochloride (Dox). Maximum drug loading was 204.54 ± 3.87, 65.97 ± 1.54, 65.95 ± 6.96, 65.28 ± 3.09, and 148.05 ± 2.24 mg of drug per milliliter of DC Bead LUMI for Dox, GARD, DSR 6434, IMQ, and BMS-202, respectively. Fast loading and subsequent rapid release in saline were observed for IMQ, GARD, and DSR 6434. These drugs could also be partially removed from the beads by repeated washing with de-ionized water suggesting weak interaction with the beads. Aggregation of IMQ was observed in water and saline. GS-9620 partially decomposed in the solubilizing solution, so loading and release were not characterized. Compared to TLR agonists, slower loading and release were observed for Dox and BMS-202. Potential factors influencing drug loading into and release from DC Bead LUMI including steric hinderance, hydrophobicity, drug pKa, and the electrostatic nature of the beads are discussed. The maximum loading capacity of BMS-202 and Dox in DC Bead LUMI exceeded the maximum theoretical loading capacity of the beads expected from ionic interaction alone suggesting additional drug-bead or drug-drug interactions may play a role. Slightly more release was observed for BMS-202 at early time points followed by a slower release compared to Dox. Further study of these drug-bead combinations is warranted in search of new tools for locoregional delivery of immune-modulating agents for treatment of HCC via drug-eluting bead chemoembolization.

A new method for hosting and sharing MATLAB Web App

Currently, using MATLAB Web App Server to deploy MATLAB Web applications for hosting and sharing interactive Web applications involves the following problems: slow loading of applications, incompatibility with some browser versions, and various shortcomings of deployment tools, such as poor scalability and difficulty in optimizing black boxes. These problems adversely affect the user experience. To address this situation, we propose the use of front-end technology to design application layouts and build an application hosting platform with front-end and back-end separation using Nginx and Python. This method is shown to be simple and efficient, and it can successfully overcome the aforementioned problems while providing new ideas for hosting and sharing.

On the time of well transition to industrial production mode

The purpose of the article wasanalysis of the reasons for the different velocity of transition of the "well-reservoir" system from one thermodynamic state to another based on experimental data on time and main energy parameters for the conditions of gas and oil and gas fields. The methods. Experimental determination of the transition time of wells to industrial production mode; and analysis of experimental data. Findings. The transition time of the "well-reservoir" system from one thermodynamic state to another is determined by the internal energy of the reservoir and depends on the energy of external influence and the determining parameters: reservoir pressure and temperature. For traditional reservoirs - collectors, including for reservoirs with low reservoir pressures, it is 104 - 107 s. For formations with high formation pressures, the forecast time for the transition of the well to the mode of industrial production or emergency release of formation fluid is 100 - 103 s. Theoriginality. The work shows that in the case of low-energy impact, structural changes in rocks in reservoir conditions occur under sublimit slow loads at the level of approximately 40...70% of the limit value of the dynamic strength of the reservoir rock. It is experimentally shown that the transition of the "well-reservoir" system from one thermodynamic state to another flows for a time that depends on the internal energy of the reservoir and it decreases from t=104 – 107 s to t=100 – 103 and from ln t = 9.3...14.8 to ln t = 0...6.9 in the case of an increase in the energy of external influence, or reservoir parameters - pressure and temperature. Practicalimplementation. The transition time of the "well-reservoir" system from one thermodynamic state to another is determined by the internal energy of the reservoir and depends on the energy of external influence and the determining parameters: reservoir pressure and temperature, as well as the energy of elastic or elastoplastic deformation of the rock. The practical value is the ability to determine the type of oil and gas deposit based on this parameter and choose equipment.

Experimental study on the behavior of a new post-grouted micropile in a tropical soil

This work aims to analyze the behavior of a new post-grouted micropile setup developed in tropical soil. Its main innovation is the use of high mechanical resistance steel pipes (N80 class) for drilling and as a structural component of the micropiles. The pipes have special manchette valves uniformly spaced to allow neat cement grout injection into the soil. Two instrumented micropiles with 0.3 m diameter (after injection) and lengths of 19.4 m and 21 m were installed at Experimental Site III of the University of Campinas (Unicamp). The geological profile of this site presents a sandy clay surface layer (porous and collapsible) followed by a layer of sandy silt (diabase residual soil). The piles were subjected to compressive slow maintained loading tests and were instrumented along their depth with strain gages. No geotechnical failure was observed during the load test. The maximum load achieved by the MC1 and MC2 micropiles were 2.210 kN and 2.470 kN, respectively. The load test data were extrapolated to estimate the ultimate geotechnical pile capacity. The extrapolated geotechnical failure load was above 2.500 kN for both micropiles and similar to those estimated by the Federal Highway Administration FHWA (2005) load capacity method. It was verified that (1) the pile material undergoes creep under stress above 25 MPa on the transversal section of the pile and (2) the debonding effect during the loading process. The micropiles showed higher values of skin friction compared with other piles installed in the same geological-geotechnical context (tropical soil).