Static State Research Articles

Comparing Mechanical Characterization of Carbon, Kevlar, and Hybrid-Fiber-Reinforced Concrete under Quasistatic and Dynamic Loadings

Concrete is a brittle material due to its poor tensile strength; consequently, concrete tends to crack or peel under an applied external load. Previous studies have investigated the effect of incorporating fiber into concrete, which can improve its tensile strength. In this study, the static and dynamic mechanical characteristics of three types of fiber-reinforced concrete (FRC) were examined: carbon-fiber-reinforced concrete (CFRC); Kevlar-fiber-reinforced concrete (KFRC); and a combination of both, known as carbon/Kevlar-hybrid-fiber-reinforced concrete (HFRC). This study created concrete specimens by pneumatically dispersing carbon and Kevlar fibers and mixing them with cement to comprise 1% of the weight. The mixture was then combined with aggregates and water to form the concrete specimens. When compared with the benchmark concrete specimens, it was found that the compressive strength of the CFRC, KFRC, and HFRC specimens increased by about 19% to 50%, the bending strength increase by about 8% to 32%, and the splitting strength increased by about 4% to 36%. Specifically, the HFRC made with the 24 mm carbon and Kevlar fibers displayed the most significant mechanical strength in a static state. Furthermore, the HFRC showed superior resistance to impact compared to the benchmark concrete specimens across various impact energies, with the 24 mm carbon and Kevlar fiber HFRC showing the highest resistance. The inclusion of fibers in the split Hopkinson pressure bar (SHPB) test demonstrated a notable increase in the maximum strength, particularly in the case of the 12 mm carbon fiber combined with the 24 mm Kevlar fiber in the HFRC specimen.

Structural Effects of Fins Inclination Angles on Vented Brake Disc

An automobile brake disc is speed control mechanism used in most vehicles. The component is subjected to high mechanical stress, because it converts the kinetic energy of a moving vehicle into thermal energy. Therefore the component is prone to damages which can leads to brake failure resulting to lost of lives and properties. However, most researchers are more concern with methods to improve the heat dissipation of the vented brake disc, without giving much emphasis to the angle of inclination of the vents which can leads to some structural problem. Therefore, this paper aimed at investigating the effects of the internal fins inclination angles on the vented brake disc. A static state structural analysis was performed using Solidworks Simulation software on three brake disc models, with fins at 90o, 60o, and 30o inclination. The results shows that the model with fins at 90o inclination has the lowest von misses stress (714,044.9N/m2), deformation (1.7x10-4mm) and strain (9.135x10-6)which leads to its high Factor of Safety than the two models. It is hereby recommends that, the length of the fins or vents should be position along R, R1 and R2 in order to reduce stress generation on the brake disc. However, further research work should be done to investigate the thermal performance of these three models. However, another work should be carryout by elongating the length of these fins to be position along R, R1and R2.

Drifting Home: The Quests of Chinese Tourist-Migrants in Tibet

There are heated discussions in tourism studies literature regarding the definition of “home.” This longitudinal ethnography of Chinese tourist-migrants in Tibet finds home to be an ongoing introspective building over time rather than a static state, and it contends that the concept of “home” and “away” should be conceived as different stages and forms in individual life quests for home. Challenging conventional perceptions of home and tourism, the article offers theoretical insights for studies of mobile populations and conceptualizations of home and away based on the author’s non-consecutive fieldwork in Tibet of more than 16 months during a 16-year period. This research also contributes to the field of home studies in tourism mobilities and provides fresh insights into mobility in China’s current society. The search for home suggests new metaphors for understanding the modern urban life and the current mobile society.

Nano graphite platelets/Cu (BDC) MOF coating on polyurethane sponge: A superhydrophobic self-extinguishing adsorbent for static and continuous oil/water separation

The discharge of toxic organic solvents and industrial oil into water is one of the major problems that threaten marine ecology and human health. In this work, a flexible superhydrophobic/superoleophilic polyurethane (PU) sponge was modified by decorating Cu-benzene dicarboxylic acid metal-organic framework (Cu (BDC) MOF) as a flame retardant and nano graphite platelets (NGPs) as a superhydrophobic agent. These materials were attached to the sponge skeleton by poly (styrene-co-butyl acrylate). The PU-Cu (BDC)-NGPs sponge showed high thermal, mechanical, and chemical stability. Moreover, this composite possessed excellent oil/water separation efficiency. The prepared composite showed excellent superhydrophobicity with a water contact angle of 154° and possessed self-extinguishing properties with a limiting oxygen index (LOI) of 24.46%. The oil adsorption capacity at a static state and oil separation efficiency at a continuous oil/water separation process for PU-Cu (BDC)-NGPs sponge were 43.5–132 g/g and 96%, respectively. Moreover, PU-Cu (BDC)-NGPs sponge had excellent stability in harsh conditions and exhibited good compressibility and reusability. Overall, the Cu (BDC) MOF-NGPs coated PU sponge can be a highly efficient sorbent with durability and flame retardancy.

Chasing Shadows: Why There Cannot be a “Simple” Science of Literacy

The rhetoric of the reading wars has become more than just an armchair academic debate, but is encoded now in the very laws, house and senate bills, and legislative policies of the majority of the states. In turn, these policies are powered by staggering sums of money such as the 90-million-dollar investment of Fulton County, Georgia in a revamp of the failed No Child Left Behind initiative of two decades ago since, according to district officials, “Some college programs don’t sufficiently prepare future teachers to teach reading.” And Tennessee plans to spend 100 million dollars on their Reading 360—a program which stresses the development of “strong, phonics-based reading skills.” In this address, I contest the narrow perceptions of what has been called the science of reading movement and focus rather upon another contender for the science throne—that of Developmental Science. Using examples from emergent bilingual children's early writing, I attempt to show that any “simple” model of reading not only wastes useful data about children's literacy performances, but conflates the data with static states of being which, in turn, reduce the conceptual complexity of what is happening in terms of literacy development. Developmentally speaking, my contention is that models based upon the science of reading demand a slavish focus on the alphabet and figural convention. However, Developmental Science challenges the literacy field to embrace the complexity of the developmental processes, and as Vygotsky further argued, “bring the child to an internal understanding of writing” in whatever language that may be.

Light-assistance in nitrogen fixation to ammonia by highly dispersed Cs-promoted Ru clusters supported on ZrO2

Light-assisted N2 fixation to NH3 under mild conditions is attracting massive attention to circumvent energy crisis and global warming. Herein, highly dispersed Cs-decorated Ru sub-nanometric clusters supported on ZrO2 NPs have been prepared by means of MOF-templated transformation method. The obtained catalyst exhibited N2 hydrogenation activity of 1.6 mmolNH3 gcat−1 h−1 in the dark (350 °C, 0.1 MPa). Remarkably this value increased by over 300 %, reaching 5.1 mmolNH3 gcat−1 h−1 (204 mmolNH3 gRu−1 h−1) under 1 Sun power illumination (1080 W/m2) The influence of the incident light wavelength has been evaluated, revealing 81 % and 213 % enhancement in the NIR and visible region, respectively. DFT calculations were carried out to understand the static adsorption states of Ru sub-nanoclusters. Mechanistic studies have confirmed the co-existence of a photothermal and a nonthermal-hot electron mechanism. XPS, PXRD and FTIR analysis have determined that the Cs species block surface Zr4+ acidity, increasing the basicity of the ZrO2 support. Moreover, partially reduced Csδ+ (0 <δ < 1) species surrounding the Ru active sites are donating electron density to the adjacent Ru sites, favoring N2 adsorption and subsequent activation. Finally, this photocatalyst has shown an extended stability for 100 h irradiation under continuous flow.

Method of thermal calculation of the locomotive traction engine armature

A verification calculation of traction engines of locomotives is proposed, taking into account the temperature mode. Analytical expressions for the static thermal state of the engine are obtained, reflecting the balance of heat release and heat removal powers. Keywords: locomotive, engine, armature, reliability, electric drive, heating, operation, heat flow, mathematical model. lam75@mail.ru, glazunovdm@yandex.ru, ats@rgups.ru

Determination of the Static Thermoelastic State of Layered Thermosensitive Plate, Cylinder, and Sphere

Determination of the Static Thermoelastic State of Layered Thermosensitive Plate, Cylinder, and Sphere

Liquidity and Stillness: The Sea and Shore and the Furo in Kore-eda Hirokazu’s Cinema

This paper focuses on two recurring cinematic spaces of water: the sea and shore and the furo (Japanese bathroom) in the films of the contemporary Japanese auteur Kore-eda Hirokazu. 1 To develop a somatechnical perspective to address the dynamics between water, bodies and technologies, I deploy the notion of ‘the domestication of water’ ( Macauley 2005 ), denoting the process of how humans make a constant effort to maintain water in a state between liquidity and stillness. This lived interaction between humans and water can illuminate the leitmotif of kinship through the two cinematic spaces. In so doing, I firstly focus on the final shots of the sea and shore from Maborosi (1995) and Our Little Sister (2015). The mise-en-scène of the sea and the shore can create a vision of stillness on the surface but also a sense of liquidity underneath, illustrating that kinship is an ongoing process which can never be shaped but is constantly being re-shaped. Following the flow of water, I then observe the space of the furo in Still Walking (2008) and Like Father, Like Son (2013). By examining two bath routines, co-bathing with children and bathing-in-turn, I argue that the water in furo is by no means in a still state but rather is always circulating between different bodies. The circulation can not only help nurture the parent-child intimacy through co-bathing, but it also enables a theatrical stage on which to convey conflicts of kinship via bathing-in-turn. In conclusion, by further linking the representation of water and kinship in Kore-eda’s cinema, I propose the idea of liquid kinship: a lived process of making rather than a static state of being. The domestication of water between stillness and liquidity epitomises this liquid form of kinship.

Relay-Switching-Based Fixed-Time Tracking Controller for Nonholonomic State-Constrained Systems: Design and Experiment

Dear Editor, This paper investigates the fixed-time trajectory tracking controller design for nonholonomic chained systems with static state constraints. Firstly, a fixed-time tracking control law is given to carry out relay switching, which divides the controller development process into two stages. For the goal of designing fixed-time tracking controller in the second stage and avoiding the explosion of complexity, fixed-time filters are introduced. Under these preparations, a fixed-time tracking controller is elaborated by applying barrier-Lyapunov-function-based backstepping. In addition, a new tracking controller is also proposed to guarantee that the tracking error system is bounded before switching. It has been proved that the resulting closed-loop tracking error system states converge to a small neighborhood around zero within a fixed time and output states are kept in the predefined constrained regions.

Experimental study and prediction of two-phase flow pattern distribution diagrams in multi-channel cylinder dryer

The multi-channel cylinder dryer (MCD) is designed to improve heat transfer. Although there are numerous research studies on the pressure drop, heat transfer characteristics, and flow pattern in static state of MCD, there is little research on the flow pattern in the rotating state. In this paper, the distribution of flow pattern in MCD under different rotating speeds and steam mass flow rates is studied. Furthermore, the logistic regression method (LR) is used to predict the flow pattern diagrams. The results show that in the front section of the flow channel, the flow pattern is basically annular flow, which is not affected by mass flow rate and rotating speed. On the other hand, wavy flow, vortex flow, slug flow, and bubble flow can be observed when the fluid enters the middle and the end section. The higher the rotating speed and the steam mass flow rate, the more the flow pattern tends to be an annular and wavy flow. At the end of the passage, the flow pattern is mainly slug flow. The predicted flow pattern diagrams are in good agreement with the experimental result, and to obtain an effective flow pattern in the middle and the end section of the flow channel, the influence of increasing rotating speed is greater than that of increasing steam mass flow rate. However, the specific rotating speed, steam mass flow rate, and other parameters should still be set by combining with the actual situation. This work can provide some references for the further study of MCD flow characteristics.

CMB power spectrum for emergent scenario and slow expansion in scalar–tensor theory of gravity

We analyze the stability of the Einstein static universe in scalar-tensor theory of gravity, and find it can be stable against both scalar and tensor perturbations under certain conditions. By assuming the emergent scenario originating from an Einstein static state, followed by an instantaneous transition to an inflationary phase, we study and obtain the analytical approximations of the primordial power spectrum for the emergent scenario. Then, we plot the primordial power spectrum and CMB TT-spectrum of the emergent scenario and the slow expansion scenario. These figures show that both of these spectra for the slow expansion scenario are the same as that for $\Lambda$CDM, and the spectra of the emergent scenario are lower than that for $\Lambda$CDM at large scales.

3D Ag(I) coordination polymer sandwiched by water-muconate anionic layers: Synthesis, structure, Hirshfeld surface analysis, binding with BSA, and photocatalytic activity

The sonochemical reaction between silver salt, 1,3-bis(4-pyridylpropane (bpp) and trans,trans-muconic acid (H2muc) formed an Ag(I) coordination polymer with a 3D supramolecular sandwich architecture, {[Ag8(bpp)8(H2O)3].(muc)4.29(H2O)}n, (1) consisting of the silver-bpp cationic host that alternates with 2D water–muc guest anionic layers. The latter is formed by H-bonded water molecules-anions comprising hexagonal (H2O)6 clusters. The Hirshfeld surface and fingerprint plots have been used to quantify the weak intermolecular interactions in the crystal packing arrangement. The study showed that intermolecular hydrogen bonds are the most critical in constructing the titled supramolecular complex, accounting for 51.2% of the total Hirshfeld surface. Several spectrofluorimetric methods have been employed to investigate the binding interaction between Bovine Serum Albumin (BSA) and the titled complex. The complex induced significant fluorescence quenching of BSA, indicating a strong binding affinity for the protein. Static or ground state complex formation was envisaged as the primary quenching mechanism when the complex interacts with BSA. In addition, the Ag compound also offers photocatalytic properties by degrading the toxic organic methylene blue dye.

Removal effect of typical pollutants from stormwater runoff in ecological ditches.

Ecological ditches are a typical ecological facility for controlling road stormwater runoff pollution; they mainly remove harmful pollutants from runoff through plant absorption, retention and sedimentation, ecological adsorption, and microbial action. In this paper, according to the transport form of rainwater in the ditches, the removal effects of two different types of ditches on nitrogen, phosphorus, heavy metals, and other pollutants were simulated under three conditions of rainfall, slow flow, and still water, respectively, and their operating characteristics were analyzed. The results showed that the removal rate of TN in the two ecological ditches under slow flow conditions showed a downward trend as a whole with the increase of hydraulic load, and the suitable hydraulic load for TN removal should be selected as 0.3 m3/(m2 day). Under the simulated rainfall conditions, the TN removal rates of no. 1 and no. 2 ditches were 26.1-37.2% and 24.9 ~ 52.5%, respectively, and the TP removal rates were 44.6 ~ 63.3% and 36.1 ~ 62.1%. After 19.4h and 22.1h in the static state, the TP concentration in no. 1 ditch and no. 2 ditch reached the surface V water standard, and the average removal rate of TP was 74.7% and 53.7%, respectively. This paper provides a reference for selecting suitable parameters and optimizing the operational performance of ecological ditches to reduce runoff pollutants more effectively.

Study on dynamic strength and liquefaction mechanism of silt soil in Castor earthquake prone areas under different consolidation ratios

Under the Castor earthquake, there is a risk of liquefaction instability of saturated tailings, and the evolution of dynamic pore pressure can indirectly reflect its instability process. Before applying dynamic loads, the static stress state of soil is one of the main factors affecting the development of soil dynamic strength and dynamic pore pressure, and there are significant differences in soil dynamic strength under different consolidation ratios. This paper conducted dynamic triaxial tests on saturated tailings silt with different consolidation ratios, and analyzed the dynamic strength variation and liquefaction mechanism of the samples using the discrete element method (PFC3D). The results showed that 1) as the Kc′ gradually increased, and there was a critical consolidation ratio Kc′ during the development of the dynamic strength of the sample. The specific value of Kc′ was related to the properties and stress state of saturated sand. The Kc′ in this research was about 1.9. When Kc &amp;lt; 1.9, dynamic strength was increased with the increase in Kc; when Kc &amp;gt; 1.9, dynamic strength was decreased with the Kc. 2) Under the impact of cyclic load, when samples were normally consolidated (Kc =1), the pore water pressure would tend to be equal to the confining pressure to cause soil liquefaction. In the case of eccentric consolidation (Kc &amp;gt; 1), the pore water pressure would be less than the confining pressure, thus, the soil liquefaction would not be induced, and the pore pressure value would decrease with the increase of consolidation ratio. This paper provides engineering guidance value for the study of dynamic strength and liquefaction mechanism of tailings sand and silt in Castor earthquake prone areas under different consolidation ratios.

Postures of the Head, Upper, and Lower Neck in Forward Head Posture: Static and Quasi-static Analyses

Background: Abnormal head and neck postures play a significant role in developing cervical spine dysfunction. Forward head posture (FHP) is one of the most common findings in individuals who experience head and neck disorders. Objectives: This study used a photographic method to analyze the head, upper neck, and lower neck postures in forward head posture in both static and quasi-static states. Since timely diagnosis and appropriate treatment are important in preventing further complications of this kinematic chain disorder, the postural variables of the head and neck were evaluated by focusing on their separate parts in both static and quasi-static states. Methods: This observational-analytical case-control study included 175 individuals with no history of neck pain in the past 6 months, 138 with FHP, and 37 with non-FHP. The postural angles, including the upper cervical, lower cervical, craniovertebral, head posture, and head tilt angles, were measured through photography in both the static state (with the head and neck in a neutral position) and the quasi-static state (while moving the head and neck in the sagittal plane) in a sitting position. The measurements were taken in two groups (FHP and non-FHP). Results: In a static state, the upper cervical angle was higher in the FHP group than in the non-FHP group. The lower cervical measurements were higher in the non-FHP group than in the FHP group. In the quasi-static state, significant differences existed in the changes of the upper cervical, lower cervical, craniovertebral, head postural, and head tilt angles between the two groups (P-value &lt; 0.05). Conclusions: During full flexion to full extension of the neck, subjects with FHP exhibited reduced mobility in the cervical spine, particularly in the lower cervical region. Additionally, the position of the head relative to the neck remained unchanged in this group.

Removal of AM-FM harmonics using VMD technology for operational modal analysis of milling robot

The dynamics of a milling robot have a significant impact on machining efficiency and quality. Traditional experimental modal analysis (EMA) is used to study the dynamics of milling robots in the static state. However, the dynamic properties of milling robots change when they are in the operational state. To investigate the dynamics of milling robots during cutting, operational modal analysis (OMA) is used. During normal cutting, milling robots are primarily excited by cutting forces that are dominated by amplitude and frequency-modulated (AM-FM) harmonic components that are caused by the fluctuation of cutting loads and spindle speeds. Such cutting forces make the dynamic parameters identified by OMA inaccurate. To address this issue, the variational mode decomposition-OMA (VMD-OMA) method is proposed herein, which involves removing AM-FM harmonic components from the response signal using the VMD technology and subsequently using the stochastic subspace identification (SSI) algorithm to identify dynamic parameters. To verify the effectiveness of this method, simulations and experimental research have been conducted. The simulation results demonstrate that the dynamic parameters identified by VMD-OMA are generally closer to the theoretical values. Experimental research conducted on a milling robot named TriMule shows that VMD-OMA can effectively eliminate AM-FM harmonics in response signals and identify the dynamic parameters of TriMule during cutting.

Optimizing Icon Sizes on In-Vehicle Panels to Minimize Perception Time and Prevent Driving Crashes

Distracted driving increases the risk of driving errors and accidents, and it has become the main factor leading to accidents. Currently, a large amount of information is displayed on in-vehicle panels, which possibly distract drivers’ attention, diverting their gaze from the road. To minimize the negative impact of distracted driving, this study sought to optimize the design of icons presented on vehicle screens. We investigated the effect of icon size, icon position, driving state, and age on drivers’ perception time, driving performance, and subjective evaluations. A total of 42 drivers (26 men and 20 women) between the ages of 22 and 70 years participated in the study, completing a simulated driving task and a secondary visual task. The results demonstrated significant main effects of icon size, driving state, icon position, and interaction effects. Participants spent a longer time perceiving smaller icons on the center control panel in the driving state. As the icon size increases, perception time decreases at a reduced speed. During the static state, perception time leveled out from 44′ while during the driving state, perception time leveled out from 80′. On the instrument panel, perception time leveled out from 60′ while on the center control panel, perception time leveled out from 80′. Subjective evaluations supported behavioral data on the effect of icon size. Our results indicated the importance of strategic design for icons on vehicle screens, which could reduce the visual workload, then reduce the risk of traffic accidents. According to the results, enterprises or designers could target the design of icon size according to different types of in-vehicle panels or screens.

Evaluation the injectability of injectable microparticle delivery systems on the basis of injection force and discharged rate

BackgroundSubcutaneous injection of biopharmaceutical agents or microparticles is challenging due to issues with low injection efficiency and high residual amounts. ObjectiveThis study aimed to determine the important factors affecting the injectability of microparticle delivery systems, establish a suitable injection system with lower injection force and higher discharge rate, and eventually develop a reliable injectability evaluation system for injectable microparticle delivery systems in vitro and in vivo. MethodsThe effects of various parameters, including particle size, injection speed, concentration of microspheres suspension, vehicle viscosity, needle length and gauge were evaluated by measuring the injection force and discharge rate. The characteristics of microparticles and rheological measurement of the suspension systems were studied. A design of experiment approach was utilized to evaluate the interaction between the microsphere suspension, vehicle viscosity and needle gauges. Both in vitro sieve tests and in vivo tests in rats were conducted to evaluate injectability. ResultsThe in vitro test results showed that the vehicle viscosity and injection speed have varying effects on discharge rate and injection force, respectively. Particle size and needle gauge have substantial influence on injectability, larger particle size and smaller needle gauges resulting in poor injectability, while the needle gauge was found to have the greatest influence on injectability. Levonorgestrel (LNG) microsphere and glass bead were relatively uniform spherical, the glass bead had extremely smooth surface; while mesoporous silica had irregular shape. The settling rate of glass bead was the fastest, which was about 18 times faster than the LNG microsphere. The CMC-Na had a poor interaction with the LNG microspheres, glass bead and mesoporous silica and showed basically Newtonian behavior in the shear rate range of 0.1 s−1–100 s−1. When shear rate increased to more than 100 s−1, no obvious shear thinning behavior was observed. CMC-Na formed a nodule structure with whether LNG microspheres or the glass beads, which were much lower than that with the mesoporous silica in static state, among which the glass beads were the weakest. The viscosity of the suspension increased with the rising of the volume fraction of particles. Fundamentals of hydrodynamics in capillaries were referenced, such as Navier-Stokes Law equation, Krieger-Dougherty (K-D) equation, Hagen-Poiseuille equation. The best results achieved was using a suspension concentration of 120–240 mg /mL and a viscosity of 60 cP at 20 °C with 23-gauge needles. The optimized conditions were verified in vivo tests. It was proven that the LNG microsphere suspension had a good injectability when injected into subcutaneous tissue of rats. ConclusionThe injection system of injectable microparticle delivery system with lower injection force and higher discharge rate was established and the evaluation method was suitable for the injectability evaluation both in vivo and in vitro. Improved injectability would promote the clinical translation of microparticle delivery systems.

A Novel UAV-Assisted Multi-Mobility Channel Model for Urban Transportation Emergency Communications

With the increasing requirements for unmanned aerial vehicle (UAV) communication in various application scenarios, the UAV-assisted emergency communication in urban transportation scenario has received great attention. In this paper, a novel UAV-assisted UAV-to-vehicle (U2V) geometry-based stochastic model (GBSM) for the urban traffic communication scenario is proposed. The three-dimensional (3D) multi-mobilities of the transmitter (Tx), receiver (Rx), and clusters are considered by introducing the time-variant acceleration and velocity correspondingly. The velocity variation of the clusters is used to simulate the motion of vehicles around the Rx. Moreover, to describe the vehicles’ moving states, Markov chain is adopted to analyze the changes in cluster motion states, including survival, death, dynamic, and static states. By adjusting the scenario-specific parameters, such as the vehicle density (ρ) and dynamic–static ratio (Ω), the model can support various urban traffic scenarios. Based on the proposed model, several key statistical properties, namely the root mean square (RMS) delay spread, temporal autocorrelation function (ACF), level-crossing rate (LCR), power delay profile (PDP), and stationary interval, under different clusters and antenna accelerations are obtained and analyzed. The accuracy of the proposed model is verified by the measured data. The results demonstrate the usability of our model, which can be provided as a reference for the design, evaluation, and optimization of future communication networks between UAV and vehicles in urban transportation emergency communications.