Fill Time Research Articles

Balanced Electric-Magnetic Absorber Green’s Function Method for MoM Matrix Thinning and Conditioning

A balanced (Weston-type) absorber, characterized by both electric and magnetic loss mechanisms, can be placed within the null field inside the equivalent surface currents replacing a perfectly conducting or homogeneous scatterer. The absorber, referred to as the filler, substantially reduces the interactions between pairs of opposing basis/testing functions. The resultant moment matrix, formulated with the filler Green’s function (GF), is thinned accordingly. Moreover, most annulled elements need not be computed at all, thereby reducing substantially the matrix fill time. The lossy nature of GF also serves to eliminate spurious internal resonances and thus makes the electric or magnetic field integral equation matrix to be well conditioned without resorting to a combined field integral equation.

Impact of delayed prescription fill on readmission rates for chronic obstructive pulmonary disease and heart failure

ObjectivesIn an effort to reduce reimbursement penalty from the Centers for Medicare & Medicaid Services, hospitals have looked to evaluate the effectiveness of existing programs as well as adopt innovative practices to reduce 30-day readmission rates. The objective of this study was to evaluate the impact of delaying prescription fill on 30-day readmission rates for patients with heart failure (HF) and chronic obstructive pulmonary disease (COPD). Identifying an association between delaying prescription fill and readmission rate would validate programs that provide patients with their medications before discharge. MethodsA retrospective chart review was performed for all patients admitted to Henry County Medical Center with an HF or COPD exacerbation from January to October 2016. Outpatient pharmacies were contacted for each patient to determine time of prescription fill. Time of fill was compared with time of discharge, and patients were separated into 2 subgroups: those who filled within 48 hours of discharge and those who filled after 48 hours. The primary outcome was 30-day readmission rate, and a secondary end point was to identify patient characteristics associated with delayed prescription fills. ResultsA total of 104 patients were included in the study. COPD patients experienced a lower readmission rate when delaying prescription fill at least 48 hours (P = 0.23). HF patients experienced a higher readmission rate when delaying prescription fill at least 48 hours (P = 0.48). No baseline characteristics were associated with a significantly higher rate of delaying prescription fill. ConclusionDelaying discharge prescription fills resulted in a nonsignificant increase in the rate of HF readmission but did not increase the rate of readmission for COPD. Rate of delaying prescription fill was not statistically greater for any of the baseline characteristics.

Influence of structural factors on uniaxial compressive strength of cemented tailings backfill

In this paper, the influence of structural factors on the uniaxial compressive strength (UCS) of cemented tailings backfill (CTB) was experimentally investigated focusing on the filling time (FT), filling interval time (FIT) and filling surface angle (FSA). A number of CTB samples with a diameter × height of 50 mm and height of 100 mm were prepared at different FTs (1, 2, 3, and 4 stages), FITs (12, 24, 36, and 48 h), and FSAs (0, 15, 30, 45, and 60°) and subjected to UCS test to determine their mechanical strength performance. Results show that: (1) The UCS of the CTB samples decreased with the increase in FTs. The polynomial could represent the quantitative relationship between the backfill strength and FT. When the solid density (SD) within the CTB was constant, the value of the strength reduction coefficient k gradually decreased with the increase in FTs. When the SD was 65–75 wt%, the corresponding value of k remained between 0.592 and 0.967. (2) With the extension of the FIT, the UCS values of the CTB samples gradually decreased. The polynomial function could characterize the quantitative relationship between the UCS and FIT. The FIT only slightly influenced the strength performance of the CTB samples. The failure mode of the CTB samples may be tensile failure–transition from tensile failure to the shear failure-tensile shear pattern with the increase in the FIT. (3) The UCS showed a U-type distribution that decreased first and then increased with the increase in the FSAs. When the FSA changed from 0° to 60°, the UCS of the CTB samples first decreased and then increased with the FSA. The results presented in this study contribute to a better understanding of the effect of structural factors on CTB’s mechanical properties.

Abnormal ventricular repolarization in long QT syndrome carriers is related to short left ventricular filling time and attenuated stroke volume response during exercise.

Long QT syndrome (LQTS) carriers are characterized by abnormal ventricular repolarization, prolonged systole, and mechanical dispersion. Prolonged left ventricular (LV) systole has been shown to result in disproportionate shortening of LV filling in other conditions. The aim of this study was to assess LV filling, diastolic function, and stroke volume (SV) response to dynamic exercise, in a group of LQTS carriers. Forty-seven LQTS carriers (45±15years, 20 symptomatic) and 35 healthy individuals underwent bicycle stress echocardiogram. Electrocardiographic and echocardiographic measurements were obtained at rest, peak exercise, and 4minutes into recovery. Long QT syndrome carriers and controls did not differ in age, gender, heart rate, QRS duration, or LV ejection fraction. At rest, LQTS carriers had longer QTc and shorter filling time (FT). At peak exercise, QTc increased and remained longer than controls at recovery. A negative correlation was found between QTc and FT (r=-.398, P=.001) with greater fall in FT in LQTS carriers than in controls at peak exercise (-23%±10 vs +2%±3, P<.0001). FT correlated with SV (r=+.27, P=.001), which increased more in controls than in LQTS carriers (+32%±4 vs +2%±1, P<.05). These differences were more pronounced in symptomatic LQTS carriers who had shorter FT and smaller SV at peak exercise and during recovery compared to asymptomatics (P<.05). Long QT syndrome carriers have longer QTc, but also shorter FT. These disturbances worsen at peak exercise (particularly in symptomatics) compromising LV filling and SV, hence a potential pathomechanism for adverse events.

From One Medium to the Next: How Comic Books Create Richer Storylines

From One Medium to the Next: How Comic Books Create Richer Storylines

Indocyanine Green Dye Filling Time for Polypoidal Lesions in Polypoidal Choroidal Vasculopathy Affects the Visibility of the Lesions on OCT Angiography

To elucidate the factors that affect the visibility of polypoidal lesions on OCT angiography (OCTA) based on indocyanine green angiography (ICGA) findings in eyes with polypoidal choroidal vasculopathy (PCV). Retrospective, consecutive case series. Thirty-one eyes of 31 patients with PCV diagnosed on ICGA. We compared the numbers of polyps visible on ICGA and on OCTA. The following time points and durations were determined: first appearance of dye in the choroidal arteries, first appearance of dye within a polyp, and the time it took the dye to fill entire lesions. Then we compared visible and invisible polyps on OCTA in these respects. The visibility of polypoidal lessons on OCTA and, in relation to this, the time it took the indocyanine green dye to fill the polypoidal lesions. The total number of polyps detected on ICGA was 62, and 49 of these (79.0%) were imaged on OCTA. The time points determined were not significantly different, but elapsed time from the first appearance of the dye in the choroidal arteries to the first appearance of the dye within a polyp was significantly longer for the polyps that were not detected on OCTA than for those that were (5.15±2.30 seconds vs. 2.08±1.08 seconds; P < 0.001). The visibility of polyps on OCTA decreases when blood flow is slower as manifested by a longer choroid-to-polyp dye infusion time on ICGA.

INVESTIGATING THE USE OF PHASE-CHANGE MATERIALS FOR TEMPERATURE CONTROL DURING FAST FILLING OF HYDROGEN CYLINDERS

This paper explores the use of phase-change materials in the process of fast filling of hydrogen cylinders in order to limit the rise in the gas temperature by enhancing heat transfer from the gas. It is necessary to limit the temperature rise because the structural performance of the cylinder materials can be degraded at higher temperatures. Initially, two computational approaches for modeling the fast filling of hydrogen cylinders are presented and validated; the first is an axisymmetric computational fluid dynamics simulation and the second is a single-zone approach with one-dimensional conjugate heat transfer through the cylinder walls. The models are applied to study fast filling of a hydrogen-powered passenger car. The predictions show that the minimum safe fill time for Type III cylinders with aluminum liners is generally shorter than for Type IV cylinders with plastic liners, for given ambient and precooling temperatures. Alternatively, Type III cylinders require less precooling for a given fill time. Introduction of a phase-change material heat sink is assessed as a means of reducing the fill time for Type IV cylinders. Paraffin-based phase-change materials are considered. The predictions show that the use of pure paraffin wax does not help in reducing the gas temperature due to its low thermal conductivity, however materials with improved thermal conductivity, for example, mixtures of paraffin wax and graphite, can facilitate reduced fill times. Without use of phase-change material it is not possible to reduce the fill time of Type IV cylinders below three minutes unless the gas supply is precooled. While the fill time can be reduced by precooling the gas supply, the phase-change material reduces the degree of precooling required for a given fill time by 10–20 K, and reduces the minimum theoretical power consumption of the cooler by 50–100%, depending on the ambient temperature.

Uncertainty in geometry of fibre preforms manufactured with Automated Dry Fibre Placement and its effects on permeability

Resin transfer moulding is one of several processes available for manufacturing fibre-reinforced composites from dry fibre reinforcement. Recently, dry reinforcements made with Automated Dry Fibre Placement have been introduced into the aerospace industry. Typically, the permeability of the reinforcement is assumed to be constant throughout the dry preform geometry, whereas in reality, it possesses inevitable uncertainty due to variability in geometry. This uncertainty propagates to the uncertainty of the mould filling and the fill time, one of the important variables in resin injection. It makes characterisation of the permeability and its variability an important task for design of the resin transfer moulding process. In this study, variability of the geometry of a reinforcement manufactured using Automated Dry Fibre Placement is studied. Permeability of the manufactured preforms is measured experimentally and compared to stochastic simulations based on an analytical model and a stochastic geometry model. The simulations showed that difference between the actual geometry and the designed geometry can result in 50% reduction of the permeability. The stochastic geometry model predicts results within 20% of the experimental values.

Effects of Process Related Variations on Fillablity Simulation of Thin-Walled IN718 Structures

Simulation tools have improved significantly and are now capable of accurately predicting mould filling behavior. The quality of prediction is highly dependent on material properties and set-up of boundary conditions for the simulation. In this work material properties were measured and casting conditions were analyzed to accurately replicate the casting process in simulation. The sensitivity of the predictions to minor process variations commonly found in foundries was evaluated by comparing simulation and cast samples. The observed discrepancies between simulation and cast samples were evaluated and discussed in terms of their dependency on process variations. It was concluded that the simulation set-up was capable of reasonable predictions and could replicate the asymmetry of the filling however did not accurately predict the absolute value of the unfilled area. It was discovered that asymmetric flow due to variations in the orientation of the casting mould during filling could have greater influence on the predictions than the actual variation in fill time. The quality of simulation is dependent on equipment and techniques used in the foundry as well as the metallurgical model to simulate the process.

Retraction] 사출 형체력에 따른 플라스틱 렌즈의 치수편차 특성

In this paper, it is analyzed the characteristics of plastic lens dimensional deviation according to injection mold clamping force. The influences of fill time, mold clamping force, injection pressure, shear rate, etc., are examined. It was found that mold clamping forces which increased 100, 200, 300, 400, 500 kN can affect the thickness deviation of the lens. Dimensional deviation of the lens derived by injection molding was found to be 2.9% at 100 kN and 0.7% at 500 kN, the smallest observed deviation throughout the study. This indicates that mold clamping force and dimensional deviation of lens thickness were inversely proportional to each other. A prediction of filling time was 1.87 sec performed by injection molding analysis, however, filling time was observed at 1.72 sec in the actual experiment, which is 8.0% shorter than expected. This can be attributed to packing pressure.

Evaluation of Sequencing Batch Reactor Performance for Petrochemical Wastewater Treatment

Sequencing batch reactor (SBR) technology has found many applications in industrial wastewater treatment in recent years. The aim of this study was to determine the optimal time for a cycle of the sequencing batch reactor (SBR) and evaluate the performance of a SBR for petrochemical wastewater treatment in that cycle time. The reactor was operated with a suspended biomass configuration under aerobic conditions. Carbon removal and operating parameters such as pH, temperature and dissolved oxygen (DO) were monitored during the wastewater treatment. The SBR was run at different cycle times and amongst the cycle times tested, the best performance was obtained with a 7 h cycle time composed of a fill time of 15min, reaction of 6 h, settling of 30 min, and withdrawal of 15 min. The SBR with the determined cycle time was used to study the treatment of wastewater with various organic loading rates (12.88 gr COD/L.d, 18.02 gr COD/L.d and 31.39 gr COD/L.d). The SBR performance was evaluated by chemical oxygen demand (COD), total solids (TS) total suspended solids (TSS) removal efficiencies. During the shock loading tests, the maximum COD, TS and TSS removal efficiencies were 84%, 67% and 92%, respectively.

Multimode time-dependent gyrotron equations for different time scales

Development of gyrotrons requires careful understanding of different regimes of gyrotron oscillations. For a long time, the gyrotron theory was developed assuming that the transit time of electrons through the interaction space is much shorter than the cavity fill time. Correspondingly, it was assumed that during this transit time, the amplitude of microwave oscillations remains constant. However, there are situations when this assumption is not fulfilled, or is marginally fulfilled. In such cases, a different mathematical formalism has to be used. The present paper generalizes the new formalism to the multi mode case. The particular example considered indicates that in some cases the results obtained by means of the old and the new formalism differ significantly.

Inkwells for on-demand deposition rate measurement in aerosol-jet based 3D printing

Aerosol-jet printing (AJP) is an important direct-write printing technology based on additive manufacturing methods. Numerous research groups have utilized AJP for the fabrication of electronic circuits and devices. However, there has not been any real-time or even any on-demand method for quantitatively measuring and/or setting the deposition rate of an AJ ink stream. In this paper, we present a method for measuring the deposition rate of an AJ ink stream by printing into an array of inkwells that were fabricated using photolithography and were characterized using x-ray tomography and optical profilometry. These inkwell arrays were then used to establish a set of deposition rates namely 0.0011, 0.0024, 0.0035, 0.0046 and 0.0059 mm3 s−1 that were subsequently compared with independently-measured deposition rates obtained by printing the ink stream into a weighing pan for a specified time and calculating the resulting deposition rate from the weight of the printed sample. From this comparison, it is observed that, for a human operator, the error in setting a specific deposition rate is less for inkwell fill times greater than 3 s and greater for fill times less than 3 s. This observation indicates that the average volume of an inkwell array should be at least three times the desired deposition rate (Vinkwell > 3R). It was also observed that when the diameter of the inkwell was only slightly larger than the ink stream diameter, the ink uniformly wets the sidewall of the inkwell and results in a well filled inkwell for which the point at which it is just fully filled is easily observable. Finally, the interactions of the ink with both ‘philic’ and ‘phobic’ inkwells were studied illustrating the ability to use inkwells of various materials for setting the desired deposition rates for a variety of AJ printable inks.

Precision Ocular Drug Delivery Via Aerosol Ring Vortices.

Despite being the most prominent dosage form for topical ocular delivery, eye-drops have several well-recognized drawbacks. Addressing these limitations, in this work we introduce a novel method to accurately deliver ophthalmic medications to the surface of the eye at relatively low volume and low velocity. By aerosolizing a medicament and dispensing it in the form of a toroidal vortex, commonly known as a "smoke ring", several major drawbacks associated with topical drug delivery can be avoided. A device capable of emitting a toroidal vortex was developed such that actuation force and aerosol loading could be modulated. Different solution formulations were tested for deposited dose on an in vitro eye. It was found that the dose delivered to the surface of an in vitro eye was directly proportional to the velocity and the size of the droplets emitted from the device. With a dilute solution formulation (0.05% fluorescein sodium), doses could be reproducibly deposited by actuating the device at different velocities (from ~5ng to ~18ng per actuation). While a more concentrated solution of 0.5% fluorescein sodium, between 20ng and 160ng could be deposited depending on selected actuation velocity. And with the highest concentration, 5% fluorescein sodium, 1.15 +/- 0.075μg was deposited. It was also shown that the amount of drug deposited onto the eye surface could be modulated by modulating the chamber fill time. Precise toroidal vortex based aerosol delivery may facilitate optimized administration of medicines to the surface of the eye.

Analytical and numerical study on the fast refill of compressed natural gas with active heat removal

Heavy-duty vehicles powered by compressed natural gas (CNG) store the fuel in large onboard cylinders. Fast fill of depleted CNG cylinders is a common refueling method because it achieves refueling time comparable to liquid fuels. However, under-filling of CNG cylinders occurs during fast fill due to the recompression work of CNG in the cylinder that heats the fuel during the fill. The heated fuel has a lower density at the rated pressure, and thus less mass of CNG can be stored than if it was at ambient temperature. To increase the mass of dispensed CNG during fast fill, an active heat removal method is proposed. In this study, analytical and numerical models of the filling process of CNG into a Type-III cylinder with and without active heat removal are developed. In the analytical study, mass and energy conservation equations are coupled with an ideal-gas equation of state and orifice flow equations to predict the heat generation rates during fast fill. The influence of heat removal via a cooling coil inserted into the cylinder during fill on the dispensed mass and fill time is quantified. The analytical study is compared to numerical simulations employing a two-dimensional axisymmetric computational fluid dynamics (CFD) model for unsteady, compressible turbulent flow in a Type-III cylinder with and without active heat removal. Dynamic average temperature, pressure and mass curves as well as the local temperature distribution in the cylinder are obtained at different time instances during the fill. The effect of the location of the heat removal coils is also investigated. The results of the analytical/numerical study illustrate the benefit of heat removal from the cylinder as a means of improving fast-fill efficiency in natural gas fueled heavy-duty vehicles.

Reinforcement Effect of Polyacrylamide on Dredger Fill Improved by Vacuum Preloading

A series of laboratory tests were carried out to evaluate the effectiveness of polyacrylamide (PAM) on dredger fill combined with the vacuum preloading method. Five groups of vacuum preloading model tests were conducted, and the groups were mixed with 0, 15, 30, 60, or 90 mg/L PAM. The test results indicated that the optimal dosage of PAM is 30mg/L for the Tianjin Binhai dredger fill with a water content of approximately 300%. The optimal dosage of PAM can not only considerably shorten the consolidation time of the dredger fill but can also notably increase the rate of dissipation of excess pore pressure. An approximately 70% increase in the vane shear strength was also observed. Mercury intrusion porosimetry was performed to analyze the pore characteristic parameters of the soil samples after vacuum preloading combined with PAM, and the results revealed that an excessive dosage of PAM can lead to relatively bigger pore diameter in the soil samples.

An Efficient Broadband Adaptive Beamforming Algorithm Based on Frequency–Space Cascade Processing

In this paper, the performance loss caused by the aperture fill phenomena and heavy computational burden in broadband adaptive beamforming (ADBF) is analyzed, and an efficient approach based on frequency–space cascade processing is presented. First, a digital compensation method is applied to compensate for the aperture fill time of the broadband phased array in the range-frequency domain, removing the dependence of the wideband array steering vector on the instantaneous frequency. Second, a subband adaptive beamforming scheme using range-compressed data is implemented, reducing the degrees of freedom of wideband jamming and avoiding signal cancelation in the ADBF covariance matrix estimation. Moreover, the conjugate gradient algorithm is used to iteratively calculate the ADBF weight vector to reduce the computational complexity. Finally, wideband ADBF can be achieved by subband synthesis. Theoretical analysis and simulation results are provided to demonstrate that the proposed approach can suppress jamming sufficiently with a rapid convergence rate, making this approach feasible for engineering implementation.

Optimisation of filter design and operation for wastewater treatment sludge

Abstract Wastewater treatment (WWT) produces a biomass or sludge that must be dewatered in order to reduce its volume and subsequent disposal costs. Although WWT sludges can be compressed to high solids concentrations under enough force, they are also highly impermeable such that it takes a long time to remove the water. This leads to low throughputs for dewatering devices such as filters and centrifuges, which means that dewatering contributes a significant proportion of the overall cost of WWT. Improvements to throughput at a given final solids concentration or higher solids concentrations at a given throughput can represent substantial cost savings to the WWT industry. Recent developments in understanding the highly compressible nature of WWT sludges have led to a fundamentally rigorous description of their dewaterability. In addition, methods have been developed for measuring their compressibility and permeability over a broad range of solids concentrations, which allows the prediction of their behaviour using models of dewatering devices. In this work, the dewatering properties of an Australian WWT sludge are used in a validated model of flexible-membrane or diaphragm plate-and-frame filtration. The model is used to optimise the filtration time to give the maximum throughput for various values of cavity width and handling time. Flexible-membrane filtration is versatile in that there is a given squeeze time to reach a certain solids concentration for each fill time, but there is only one combination of fill and squeeze that maximises the throughput. This work shows that, due to the highly impermeable nature of WWT sludges, the maximum throughput is when the fill time is the shortest such that filter presses for WWT sludges are optimally operated by loading enough sludge to fill the press and then immediately squeezing. For slow-filtering materials such as WWT sludges, the maximum throughput varies inversely with cavity width such that small cavity widths, within the constraints of cake release, are preferable.

Design and evaluation of an enhanced constrained rod casting mould for experimental characterisation of hot tearing in aluminium casting alloys

The most popular mould configuration for hot tearing evaluation of aluminium alloys, the Constrained Rod Casting (CRC) design, was evaluated via computer modelling. Filling patterns, heat flows, and shrinkage areas were assessed using the existing published design, and improvements in the design were generated. A mould of the improved design or Enhanced Constrained Rod Casting (ECRC) was fabricated and successfully used to evaluate the hot tearing tendencies of A206.2 and A380 die casting alloys. The ECRC mould reduced fill time and increased uniform filling of the constrained rods, which resulted in more uniform solidification rates for all the constrained rods. The ECRC mould and novel measurement technique predicted hot tearing in real time of A206.2 and A380 die casting alloys at initial pouring temperatures of 700, 760, and 800 °C. The A206.2 alloy exhibited hot tearing characteristics at the measurement rod while A380 did not show any hot cracking defects.

Computer-Aided Design and Engineering for M16 Handguard Manufacturing

This work presents a computer-aided design and engineering CAD/CAE for design and optimization of M16 handguard manufacturing. A new design of handguard was developed in term of various combinations of supporting ribs inside the component. Finite Element Analysis (FEA) was used to simulate the stress distribution as well as the evaluation of supporting ribs in the component. The injection molding was used for production of the hand guard; therefore, the CAE was used to simulate the effect of gate location and gate type on the weld lines. The excessive-flash technique, which extends the fill time and continues the melt lines to flow after the melt recombination, has been introduced in order to reduce the weld lines. The simulation results indicated that the stress concentration in the loading and vent holes regions had the potential to cause the handguard to fracture. However, the combinations of vertical and horizontal ribs can reduce the stress concentration in the component. The weld lines located near the vent hole, in which the melt fronts came in contact with each other. The type and location of gates did not affect the weld line while the weld lines were observed to be strongly influenced by the excessive flash.