Time Spacing Research Articles

The Effect of Spacing and Weeding Time on growth and production of Bawang Sabrang (Eleutherine Americana Merr.)

The potential of sabrang onions as a medicinal plant for industrial scale is very large because these plants can grow and adapt in all climates and types of soil with a relatively short harvest time (3-4 months). This research aim was to determine the effect of spacing treatment and weeding time as well as their interaction with the growth and production of sabrang onions (Eleutherine americana Merr.). Penelitian ini dilakukan di Fakultas Pertanian, Universitas Sumatera Utara, Medan dengan ketinggian + 32 meter di atas permukaan laut, yang dimulai pada bulan September hingga Desember 2017. The research design used was Factorial Randomized Group Design with two factors. The first factor is the spacing with 3 types, namely: 10 cm x 20 cm; 15 cm x 20 cm; 20 cm x 20 cm and the second factor is the time of weeding with 4 types, namely: Weeds are weeded up to 28 days after planting, then weeds are left to harvest; Weeds are weeded up to 56 days after planting, then weeds are left to harvest; Weeds are weeded up to 84 days after planting, then weeds are left to harvest; Weeds are weeded up to 14 days after planting, then weeds are left until harvest. The observation parameters were plant height, number of leaves per clump, number of tubers per clump, tuber wet weight per clump, tuber dry weight per clump, tuber wet weight per plot, tuber dry weight per plot, and weed wet weight. The research results showed that the treatment of spacing significantly affected the number of leaves at 6 & 7 weeks after planting and the number of tubers. The treatment of weeding time significantly affected the number of tubers and weed wet weight per plot. Interaction treatment between spacing and weeding time did not significantly affect all observed parameters. The best result obtained was at a spacing of 20 cm x 15 cm or weeding time up to 84 days after planting, then weeds are left until harvest.

Multiple Fracture Growth in Modified Zipper Fracturing

Operational parameters, such as multiple-cluster and well spacing, flow rates, and injection time, play a vital role in the deviation and growth of multiple-cluster hydraulic fractures during the implementation of modified zipper fracturing technology. Fundamental analysis of the dynamic zipper fracture growth because of changing flow rates, well spacing, and injection time does not appear to have been studied in the literature, although it is of critical importance for fracturing optimization. In this study, a fully coupled two-dimensional (2D) extended finite-element method (XFEM)–cohesive zone model (CZM) in combination with a phantom-node method (CPNM) was used in ABAQUS to investigate the initiation and propagation of multiple hydraulic fractures with 10 injection clusters that are distributed in two horizontal boreholes. This study aims to assist fracturing design to achieve minimal deviation in multiple fracture propagation and create deeper and much wider fractures between two horizontal boreholes of a modified zipper fracture (MZF) completion pattern. The growth of a hydraulic fracture in an XFEM region were verified by Khristianovic–Geertsma–de Klerk (KGD) zero toughness solution and good agreement with a negligible error of <2.5% was obtained. A series of simulation scenarios was carried out with various flow rates and three well spacings of 40, 60, and 80 m, over a long injection period to identify the optimum injection time in which a fracture grows straight with minimal deviation. The results show that to create smooth and deeper multiple hydraulic fractures in zipper fracturing, an increase in the flow rate is preferred, but the duration of the injection period should be optimized. The results of this study could be used to better address operational difficulties, such as multiple-fracture crossing and closure that is associated with unfavorable injection times, well spacing, and flow rates in MZF operations.

Optimization of the conductivity of microwave components printed by inkjet and aerosol jet on polymeric substrates by IPL and laser sintering

AbstractIn this work, microwave planar resonators are printed with silver nanoparticle inks using two printing technologies, inkjet printing and aerosol jet printing, on polyimide substrates. The microwave resonators used in this paper operate in the frequency band 5–21 GHz. The printing parameters, such as the number of printed layers of silver nanoparticle inks, drop spacing, and sintering time, were optimized to ensure repeatable and conductive test patterns. To improve the electrical conductivity of silver deposits, which are first dried using a hot plate or an oven, two complementary sintering methods are used: intense pulsed light (IPL) and laser sintering. This paper presents the results of different strategies for increasing the final quality factor of printed planar resonators and the trade-offs (sintering time versus final conductivity/unloaded Q) that can be reached. Improvement of the resonator unloaded quality factor (up to +55%) and of the equivalent electrical conductivity (up to 14.94 S/μm) at 14 GHz have been obtained thanks to these nonconventional sintering techniques. The total sintering durations of different combinations of sintering techniques (hot plate, oven, IPL, and laser) range from 960 to 90 min with a final conductivity from 14.94 to 7.1 S/μm at 14 GHz, respectively.

Kaplan Oscillator Configuration by Means of Bifurcation Diagrams to Generate the P and T Waves, in Addition QRS Complex of the ECG

In this article, we examine the oscillator system developed by Kaplan that generates electrocardiogram signals ECG. The system consists of two sets coupled in a ring. Each set has a Van der Pol oscillator, a differential delay equation and a low-pass half-wave filter. The ECG is composed of the P wave, the QRS complex and the T wave. The Kaplan oscillator generates only the QRS complex, this with two different amplitudes of the R-wave and non-uniform time spacing. The damping parameter of the Van der Pol oscillator, epsilon e and the filter’s T parameter were analysed, by means of bifurcation diagrams, in order to generate the other ECG oscillations. We created a new parameter, called gamma γ, which was included in the mathematical model. This reduces the amplitude of the Van der Pol oscillator signal derivative and consequently affects the filter performance and the differential delay equation. Our new configuration obtained through analysis generates the QRS complex with constant R-wave amplitude and also constant time spacing, in addition to generating the P and T waveforms on ECG. The results are compared numerically with the actual ECG. The work resulted in advances in oscillator models that can generate heart signals.

Dynamic modeling and quantitative diagnosis for dual-impulse behavior of rolling element bearing with a spall on inner race

The dual-impulse behavior, which is produced by the spall located on the surface of the bearing raceway, is closely related to the size of the spall zone. This allows to establish an accurate mechanism of quantitative fault diagnosis and spall size estimation. However, dynamic model of dual-impulse behavior, which couples the nonlinear excitation force and the impact force induced by the interaction between the rolling element and the spall zone, have not been proposed before, especially under the elastohydrodynamic lubrication (EHL) condition. To address this issue, the corresponding dual-impulse excitation mechanism is investigated and explained, and the force produced by the collision of the rolling element with the trailing edge of the spall zone is derived. A coupled nonlinear dynamic model of the rolling element bearing (REB) with a spall on the inner race is proposed in this paper, in which the displacement and excitation force originating from the passing process of the rolling element over the spall zone are modeled as a piecewise function. The transient collision force excited by the strike of the rolling element on the trailing edge of the spall area is introduced, and the contact between the rolling elements and both the bearing races under EHL condition is modeled. To validate the proposed model, the dual-impulse time spacing (DITS) is analysed, and the vibration responses and its corresponding envelope spectra under simulation and experimental conditions are studied theoretically and experimentally. The simulated results agree well with the experimental results.

Experimental Study on The Oxidative Degradation of RO Concentrated Water by Ti/IrO2-RuO2 Electrode

Advanced treatment and reuse of wastewater is an effective way to solve the shortage of water resources in China. The advantages of RO Technology, such as better water quality and lower operating cost, have become the mainstream desalination technology for wastewater reuse. However, RO technology will produce a certain amount of concentrated water, which contains a large number of inorganic salts and soluble refractory organics. The efficient removal of refractory organics in this high salinity system has become the main bottleneck and problem faced by RO technology. In view of the difficulty of further biochemical treatment of the concentrated water in the RO unit of a sewage treatment plant, the electrochemical method is used to treat the concentrated water. The effects of electrode spacing, current density and reaction time on the treatment of RO concentrated water were discussed. The optimal operation parameters for the treatment of 300ml of the wastewater are as follows: plate spacing 1.5cm, current density 300A/m2, reaction time 20min. Under the above conditions, the COD removal rate can reach 95%, and the lower the initial COD value, the higher the degradation efficiency.

Comparing semi-landmarking approaches for analyzing three-dimensional cranial morphology.

Increased use of three-dimensional (3D) imaging data has led to a need for methods capable of capturing rich shape descriptions. Semi-landmarks have been demonstrated to increase shape information but placement in 3D can be time consuming, computationally expensive, or may introduce artifacts. This study implements and compares three strategies to more densely sample a 3D image surface. Three dense sampling strategies: patch, patch-thin-plate spline (TPS), and pseudo-landmark sampling, are implemented to analyze skulls from three species of great apes. To evaluate the shape information added by each strategy, the semi or pseudo-landmarks are used to estimate a transform between an individual and the population average template. The average mean root squared error between the transformed mesh and the template is used to quantify the success of the transform. The landmark sets generated by each method result in estimates of the template that on average were comparable or exceeded the accuracy of using manual landmarks alone. The patch method demonstrates the most sensitivity to noise and missing data, resulting in outliers with large deviations in the mean shape estimates. Patch-TPS and pseudo-landmarking provide more robust performance in the presence of noise and variability in the dataset. Each landmarking strategy was capable of producing shape estimations of the population average templates that were generally comparable to manual landmarks alone while greatly increasing the density of the shape information. This study highlights the potential trade-offs between correspondence of the semi-landmark points, consistent point spacing, sample coverage, repeatability, and computational time.

A Novel Graph and Safety Potential Field Theory-Based Vehicle Platoon Formation and Optimization Method

Platooning is considered to be a very effective method for improving traffic efficiency, traffic safety and fuel economy under the connected and automated environment. The prerequisite for realizing these advantages is how to form a platoon without any collisions and how to maintain and optimize the car-following behavior after platoon formation. However, most of the existing studies focus on the platoon configuration and information transmission method, while only a few attempt to address the issue of platoon formation and optimization methods. To this end, this study proposes a novel platoon formation and optimization model combining graph theory and safety potential field (G-SPF) theory for connected and automated vehicles (CAVs) under different vehicle distributions. Compared to previous studies, we innovatively incorporate the concept of the safety potential field to better describe the actual driving risk of vehicles and ensure their absolute safety. A four-step platoon formation and optimization strategy is developed to achieve platoon preliminary formation and platoon driving optimization control. Three traffic scenarios with different CAVs distributions are designed to verify the effectiveness of our proposed platoon formation method based on G-SPF theory, and the simulation results indicate that a collision-free platoon can be formed in a short time. Additionally, the G-SPF-based platoon driving optimization control method is demonstrated by comparing it with two typical control strategies. Compared with the constant spacing and constant time headway control strategies, the simulation results show that our proposed method can improve the traffic capacity by approximately 48.8% and 26.6%, respectively.

Study on the Correlation between Community Construction Planning Factors and the Spatial Distribution of COVID-19 Outbreak: Case Study of Main Urban Area of Wuhan

In the context of the global outbreak of COVID-19, this study took Wuhan as an example, using mathematical statistics and spatial analysis, and other methods to explore the distribution characteristics and distribution of COVID-19 in residential spaces in the main city of Wuhan. Based on the above analysis, this study summarized the influencing factors and revealed their internal connection with the spread of the epidemic, and finally proposed corresponding prevention and control strategies. The results show that: 1) The epidemic in Wuhan has significant spatial aggregation characteristics, with epidemic communities concentrated in urban areas with high population density and dense commercial areas along the Changjiang River more likely to be infected; 2) The construction planning factors of epidemic communities are closely related to epidemic density. The results indicated traffic convenience, business services and the accessibility of hospitals are significantly related to the spread of the virus. The epidemic density is highly negatively correlated with community’s land area, base area, number of households, building height, building spacing, and completion time, and may negatively correlated with the number of buildings, greening rate. But it positively correlated with community’s building density. Therefore, the epidemic prevention and control of urban residential spaces should start with improving the built environment of the community. It means, by creating a rich and diverse community flexible space, the community can effectively prevent the epidemic, and then realize the city’s comprehensive anti-epidemic and development growth.

Impact of the High‐Energy Dynamic Compaction by Multiple Compactors on the Surrounding Environment

Dynamic compaction machine (DCM) is a widely adopted ground reinforcement technology. However, dynamic compaction energy has a very significant impact on the surrounding environment. At present, the research on the impact of dynamic compaction mainly focuses on the effect of the tamping behavior of a single compactor in the working state, whereas the research on the impact of multiple compactors working jointly is rare. To study the impact of the dynamic compaction energy of multiple compactors working jointly on the surrounding environment, the dynamic response model for multiple compactors working in the same field was established based on the explicit dynamic analysis module in ABAQUS. The validity of the model was verified by comparison with the measured data. Based on this, the impact of the dynamic compaction energy of multiple compactors with different working conditions in terms of the arrangement, spacing, and working time interval was analyzed. The results showed that the arrangement and spacing of the compactors had a remarkable influence on the distribution of the dynamic compaction energy in the surrounding environment. Under the condition of multiple compactors working with a time interval of less than 10 s, the impact of the superimposed dynamic compaction energy due to the interaction of multiple compactors had to be considered.

Analysis on cracking of structure layer of cement stabilized graded macadam

Because of its strong bearing capacity, good stability and easy control of construction technology, cement stabilized graded macadam was widely used in highway pavement structure. In order to solve its characteristics of easy cracking, relevant researchers have carried out systematic studies on it, but such studies did not involve the large volume and large scope of the structural layer, and only carried out research on the specimen and small scope. Based on engineering project, the influence of dust content and cement content on the cracking was studied by adjusting the parameters and paving the test section during the production process. At the same time, the cracks in the project were counted, and the influences of exposure time, structural level, traffic load and construction level on the cracks in the cement stabilized graded macadam were analyzed. The relationship between crack spacing and exposure time is established, and through comparative analysis, it is found that construction level is the most important factor affecting crack spacing.

Biological traits of six sterile oat biotypes in response to planting time

AbstractSterile oat (Avena ludoviciana Durieu) is a problematic weed in winter crops of Australia. Biotypes of sterile oat adapted to the local environment may vary in environmental plasticity, which could increase their invasiveness. A 2‐yr (winter growing seasons of 2018 and 2019) study in Australia investigated the influence of planting date (early, mid‐, and late season) on the growth and reproduction potential of six biotypes (AL2/17, AL3/17, AL4/17, AL5/17, AL6/17, and AL9/17) of sterile oat. Averaged across biotypes, the seed production of sterile oat was reduced by 21 and 84% for mid‐ and late planting, respectively, compared with early planting (2,660 seeds plant−1). Seed production was highly correlated with the first panicle emergence for early planting. However, for mid‐ and late‐season planting, seed production was correlated with panicle number and plant biomass. For mid‐season planting, taller plants had more seed number plant−1 than shorter plants. The results of this study imply that biotypes of sterile oat differ in environmental plasticity and that they can complete their life cycle under a wide range of temperatures in the winter season and contribute to its reinfestation. Results also suggest that early and mid‐season cohorts are prolific in seed production; however, late cohorts can also produce sufficient seeds for reinfestation. Therefore, integrated weed management strategies must be focussed on those tactics (manipulation of sowing time and row spacing) that could create a competitive crop environment and to suppress the growth of early cohorts of sterile oat to reduce their seed production.

Minimizing echo and repetition times in magnetic resonance imaging using a double half-echo k-space acquisition and low-rank reconstruction.

Sampling k-space asymmetrically (ie, partial Fourier sampling) in the readout direction is a common way to reduce the echo time (TE) during magnetic resonance image acquisitions. This technique requires overlap around the center of k-space to provide a calibration region for reconstruction, which limits the minimum fractional echo to ~60% before artifacts are observed. The present study describes a method for reconstructing images from exact half echoes using two separate acquisitions with reversed readout polarity, effectively providing a full line of k-space without additional data around central k-space. This approach can benefit sequences or applications that prioritize short TE, short inter-echo spacing or short repetition time. An example of the latter is demonstrated to reduce banding artifacts in balanced steady-state free precession.

Monitoring and control airblast overpressures in an open pit coal mine

Besides ground vibrations, air transmitted vibrations or airblast overpressures (AOp), are also generated during blasting operations. Mae Moh coal mine, Thailand, has been concerned about both ground and air vibrations because the residents nearby are located less than 2 km to the southeast of the mine. Most previous studies mainly focused on the air blast prediction by using from basic generalized equations to the sophisticated Artificial Intelligence (AI) techniques. In addition, many controllable and uncontrollable parameters that affect AOp were extensively studies. Blasting operation unit at the mine uses a sequential blasting machine to detonate electrical detonators with a variety of delay time between rows and blasting directions. The wavefront reinforcement model was selected to test its theory that the levels of AOp will increase at the locations where wavefronts are reinforced and, at the same time, to recommend an appropriate delay time between rows and blasting directions that may reduce AOp. The wavefront reinforcement model accounts for input burden, spacing, and sequential delay time from blastholes to generate air wavefronts transmitted out in all directions. The overall 54 blasts were conducted and recorded AOp in dB(L) unit to test the model. Only 37 blasts that had one seismograph placed at the wavefront reinforcement area and another one placed at the non-reinforcement area could be compared. The results indicated that AOp levels were higher in areas of wavefront reinforcement compared to non-reinforcement in 29 (78.4%) of all valid blasts. Most air wavefront reinforcement occurred at in front and to the back of the blasting direction. The blasting patterns of the mine were studies and indicated that the delay time between rows or circuits should be nearly 200 ms to minimize the wavefront reinforcement areas. Graphs of cube root scaled distance were provided to illustrate the effect of blast direction on the increasing of AOp.

Simulation comparison of SSE and TDOA methods for UHF direction finding of partial discharge in substation area

Partial discharge (PD) is not only the main cause of insulation fault for power equipment, but also an important sign of insulation defects. Using the PD detection system based on ultra-high frequency (UHF) antenna array, the PD localization can be realized in air-insulation substation. At present, the methods commonly used in PD detection system localization include time difference of arrival (TDOA) method and spatial spectrum estimation (SSE) method. This paper introduced the principles of these two methods, and proposed a simulation system for PD direction finding. Using this system, the direction finding performance of the TDOA method and the SSE method under different signal-to-noise ratio, incident azimuth angle, rising edge time and array element spacing are compared. The conclusion shows that when the SNR is less than 0 dB or the element spacing is less than 0.23 m, the SSE system has better direction finding performance. When the element spacing is greater than 0.23 m, the SSE system will be fuzzy in direction finding. At this time, the TDOA algorithm can achieve higher direction finding accuracy.

Costas‐code‐based radar waveform design using adaptive weights with target scattering coefficients and optimal variable time spacing with improved ambiguity function

Costas signals are widely used in modern radar systems as frequency coded. The Costas-code-based waveform can achieve a nearly thumbtack shape of the ambiguity function (AF). However, the highest AF's sidelobe levels (SLLs) of Costas waveform equals just 1/ N times of its main lobe level height, where N is the length of the Costas code. In this study, the authors suggest a generalised Costas waveform as a ‘burst’ of weighted pulses having variable time spacing between them, calling it as weighted variable time spacing Costas (WVTSC). They computed the AF analytical formulas of the designed WVTSC. They developed an adaptation model to adapt the WVTSC to target scattering coefficients, using the interior-point algorithm. The adaptive WVTSC yields much better Doppler cut and improved delay cut in the main lobe area of the AF, in the sense of SLL reduction. Moreover, they constructed an optimisation model resulting in optimal variable time spacing between the sub-pulses. The optimised WVTSC also yields considerable improvement in the AF's recurrent SLLs, using the genetic algorithm. The adapted optimised WVTSC design is proven, through simulation, to have better sidelobe performance than that of the initial waveform, without influencing the original delay-Doppler resolution, and without need to increase N .

Influence of droplet velocity, spacing, and inter-arrival time on line formation and saturation in binder jet additive manufacturing

Binder Jetting (BJ) is a low-cost Additive Manufacturing (AM) process that uses inkjet technology to selectively bind particles in a powder bed. BJ relies on the ability to control, not only the placement of binder on the surface but also its imbibition into the powder bed. This is a complex process in which picoliter-sized droplets impact powder beds at velocities of 1–10 m/s. However, the effects of printing parameters such as droplet velocity, size, spacing, and inter-arrival time on saturation level (fraction of pore space filled with binder) and line formation (merging of droplets to form a line) are unknown. Prior attempts to predict saturation levels with simple measurements of droplet primitives and capillary pressure assume that droplet/powder interactions are dominated by static equilibrium and neglect the impact of printing parameters. This study analyzes the influence of these parameters on the effective saturation level and conditions for line formation when printing single lines into powder beds of varied materials (316 stainless steel, 420 stainless steel, and alumina) and varied particle size (d50=10–47 µm). Results show that increasing droplet velocity or droplet spacing decreases effective saturation while droplet spacing, velocity, and inter-arrival time affect line formation. At constant printing velocity, the conditions for successful line printing are shown to be a function of droplet spacing and square root of the droplet inter-arrival time analogous to the Washburn model for infiltration into a porous media. The results have implications to maximizing build rates and improving quality of small features in BJ.

Optimization of Electrocoagulation Process for the TSS and Turbidity Removal in Al-Qadisiyah Water Treatment Plant in Baghdad City by Response Surface Methodology

Electrocoagulation process was employed for the treatment of river water flows in Iraq. In this study, a batch Electrocoagulation process was used to treat river water taken from Al - Qadisiyah water treatment plant. electrolysis time, voltage and inter-electrode spacing were the most important parameters to study . A statistical model was developed using the RSM model. The optimum condition after studying the parameter effect the process was 1 cm separating, 30 volts . The RSM model shows the ideal condition of removal for both the TSS and turbidity at 1 cm, 20 volts and 55 min.

Fabrication and Characterization of Ag-Sr-Substituted Hydroxyapatite/Chitosan Coatings Deposited via Electrophoretic Deposition: A Design of Experiment Study.

In this study, silver–strontium-doped hydroxyapatite (AgSr-HA)/chitosan composite coatings were deposited on a 316L stainless steel (SS) substrate via electrophoretic deposition (EPD). The Taguchi design of experiment (DoE) approach was used to optimize the EPD parameters such as the applied voltage, interelectrode spacing, and deposition time. Furthermore, the concentration of AgSr-HA particles in the suspension was also optimized via the DoE approach. DoE results demonstrated that the “homogeneous” coatings were obtained at the deposition time of 7 min, deposition voltage of 20 V, and at a concentration of 5 g/L AgSr-HA particles in the suspension. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), antibacterial studies, contact angle, and roughness measurements were performed to characterize the optimized coatings. SEM images confirmed the deposition of chitosan/AgSr-HA on the SS substrate. The wettability studies indicated the hydrophilic nature of the chitosan/AgSr-HA composite coatings, which confirmed that the developed coatings are suitable for biomedical applications, e.g., orthopedics. The average surface roughness of the chitosan/AgSr-HA composite coatings was in a suitable range used to attach the bone marrow stromal cells. Chitosan/AgSr-HA composite coatings showed an effective antibacterial effect against Gram-positive and Gram-negative bacteria. Moreover, the coatings developed apatite crystals on their surface upon immersion in simulated body fluid.

A simple and novel effective strategy using mechanical treatment to improve the oxygen uptake/release rate of YBaCo4O7+δ for thermochemical cycles

In recent years, oxygen storage materials (OSMs) have been widely used in many fields. It would be particularly important for researchers to design high-oxygen-uptake/release-rate materials. In this study, various synthesis processes were used to successfully synthesize YBaCo4O7+δ and comprehensively investigate their potential applications. Compared with traditional solid-state reaction method and co-precipitation method, the results demonstrated that the utilization of mechanical ball milling treatment on co-precipitated precursors could lead to samples with reversible oxygen uptake/release under an oxidative atmosphere at low temperatures. The resultant materials exhibited fast oxygen absorption/desorption rate that could uptake/release oxygen directly to the equilibrium state within 9 min and 20 min, respectively. The mechanochemically ball-milled sample possessed outstanding oxygen storage performance, which could be attributed to their small particle size, the active outer surface of particles, large specific surface area, and relatively low activation energy. Moreover, the ball-milled sample also exhibited excellent cycling stability during relatively short time spacing. TG results also demonstrated that the ball-milled samples could reversibly uptake/release 2.90 wt.% of excess oxygen (while only 0.70 wt.% for solid-state samples) by adjusting the ambient temperature under pure O2 atmosphere, which would make them promising candidates in various applications. This research demonstrated that mechanical treatment could be an effective strategy to tune the properties and oxygen storage capacity(OSC) performances of YBaCo4O7+δ.