Quasi-Static Flooding Analysis Method of a Damaged Ship Considering Oil Spill and Cargo Load

When a ship is damaged at sea, it is important to predict its behavior as well as whether it is to sink or not. If the ship comes to an equilibrium, the equilibrium position and time should be estimated; otherwise, the time to sink should be estimated. Furthermore, flooding analysis should be carried out not only during the design stage of the ship for preventive reasons, but also after an accident for a better investigation of its causes. In addition, flooding analysis methods that can provide predictions in case of an accident are of particular importance, as there is no time for the required calculations in an emergency. For this purpose, a quasi-static flooding analysis method for the damaged ship in the time domain is proposed in this study. There are a number of studies in which the equilibrium position and time were estimated by flooding analysis. However, most of them have not considered the air pressure effect in fully flooded compartments, and the method of determining the fluid volume in these compartments was not accurate. In the present study, the virtual vent and accumulator method are used to calculate the reference pressure in the fully flooded compartments, and the compartment shape is considered by using polyhedral integration. Also, spilled oil and solid cargo items from the damaged ship are taken into account for realistic flooding analysis. Finally, the damage stability criteria were checked not only in the final state, but also during the entire time of the flooding, as the intermediate states can be more hazardous than the final state. To validate the feasibility of the proposed method, it was applied to a naval ship, which is considerably more stringent for damage stability. As a result, we checked the availability of this study.

DEVICE FOR CHECKING AND CALIBRATING INDICATORS OF THE RESERVE TIME OF CONSCIOUSNESS PRESERVATION BY A PERSON IN CONDITIONS OF HYPOXIA

Для обеспечения надежного функционирования индикаторов резервного времени сохранения сознания человеком в условиях гипоксии разработан специальный прибор для их поверки и калибровки. Прибор включает регулятор давления, табло для индикации эталонного давления, табло для индикации резервного времени сохранения сознания, шланг с разъемом для соединения с датчиком барометрического давления, компрессор, регулятор давления и микропроцессор. Разработанный прибор обеспечивает возможность контроля работоспособности средств коллективного и индивидуального информирования экипажа пассажиров воздушных судов о величине предельного резервного времени сохранения сознания в чрезвычайных ситуациях высотных полетов. To ensure the reliable functioning of the indicators of the reserve time of consciousness preservation by a person in conditions of hypoxia, a special device for their verification and calibration has been developed. The device includes a pressure regulator, a tableau for indicating the reference pressure, a tableau for indicating the standby time of consciousness, a hose with a connector for connecting to the barometric pressure sensor, a compressor, a pressure regulator and a microprocessor. The developed device provides the ability to monitor the performance of the means of collective and individual informing the crew of aircraft passengers about the value of the maximum reserve time for maintaining consciousness in emergency situations of high-altitude flights.

Monitoring of the Operating Membrane Condition Using PZT Based EMI of External Steel Pipe

Membrane systems are increasingly being used for treating water, wastewater, and reused water. However, membrane damage can decrease removal efficiency and hinder downstream applicability. Thus, the operating conditions of the membrane should be monitored. This study monitored the operating conditions of the membrane using lead zirconate titanate (PZT)-based electro-mechanical impedance (EMI) measurements in an external air pipe. Pilot-scale tests were performed to verify the performance of the proposed method. A pressure decay test (PDT) was performed using a PZT-attached air pipe, in which the pressure was measured using PZT, and a pressure gauge was employed to measure the reference pressure. The EMI signals changed according to the variations in the pressure inside the steel air pipe. To index the signal variation, the amplitude of the major peak was extracted and compared with the reference pressure. The amplitude of the major peak was inversely proportional to the pressure change. The pressure estimation equation was derived using a linear regression between the amplitudes of the major peak and the reference pressures. According to the results, the proposed monitoring system that utilizes the EMI of an external steel pipe is a potential solution to improve the sensitivity and speed of the PDT.

Production of Agricultural Biogas with the Use of a Hydrodynamic Mixing System of a Polydisperse Substrate in a Reactor with an Adhesive Bed

The properties, types, and physical and chemical aspects of pig slurry used in the fermentation process were presented. Characterization of the pig slurry microflora for a controlled biogas production process was performed. A pilot biogas treatment installation was presented on the example of a farm with 1100 Dan Bred fatteners kept in a grate system. The research was carried out to measure the biogas flow rate resulting from the reference pressure in the fermentor. An independent assessment of the amount of biogas and the pressure drop in the skeletal deposit was carried out. The basis for assessing the hydrodynamics of gas flow through the adhesive bed is the flow characteristic, which results from the pressure that forces this flow. In each case, the determination of this characteristic consists in determining the influence of the biogas stream on the value of this overpressure, equivalent to the pressure drop (it is tantamount to determining the total biogas flow resistance through the adhesive bed). The results of the measurements indicate the practical application of pig slurry-a substrate in a polydisperse system for the production of agricultural biogas in the context of renewable energies. The article indicates that the ferment was periodically mixed during the day, together with the fermentation of the ferment with fresh substrate. The tests were conducted for 49 days, thus demonstrating that it is more advantageous to mix the ferment hydrodynamically, obtaining a CH4 level of about 80%.

Evaluating the Impact of IMU Sensor Location and Walking Task on Accuracy of Gait Event Detection Algorithms

There are several algorithms that use the 3D acceleration and/or rotational velocity vectors from IMU sensors to identify gait events (i.e., toe-off and heel-strike). However, a clear understanding of how sensor location and the type of walking task effect the accuracy of gait event detection algorithms is lacking. To address this knowledge gap, seven participants were recruited (4M/3F; 26.0 ± 4.0 y/o) to complete a straight walking task and obstacle navigation task while data were collected from IMUs placed on the foot and shin. Five different commonly used algorithms to identify the toe-off and heel-strike gait events were applied to each sensor location on a given participant. Gait metrics were calculated for each sensor/algorithm combination using IMUs and a reference pressure sensing walkway. Results show algorithms using medial-lateral rotational velocity and anterior-posterior acceleration are fairly robust against different sensor locations and walking tasks. Certain algorithms applied to heel and lower lateral shank sensor locations will result in degraded algorithm performance when calculating gait metrics for curved walking compared to straight overground walking. Understanding how certain types of algorithms perform for given sensor locations and tasks can inform robust clinical protocol development using wearable technology to characterize gait in both laboratory and real-world settings.

Turbomachinery Loss Analysis: The Relationship Between Mechanical Work Potential and Entropy Analyses

Physics-based loss analysis methods have been developed to interpret the detailed three-dimensional and time-dependent predictions of turbomachinery CFD simulations. This paper contrasts two analysis methods for assessing loss: entropy loss analysis (Zhao & Sandberg, GT2019-90126) and mechanical work potential analysis (Miller, GT2013-95488). The two individual analyses are applied to high-fidelity simulation data for linear high-pressure compressor and high-pressure turbine cascades. The results show each analysis captures the loss generating processes in different ways, corresponding to different terms in their equations. The key loss generation processes are shown to be turbulent and mean viscous dissipation in the mechanical work potential analysis, and mean viscous dissipation and turbulence production in the entropy loss analysis. A relationship between the two approaches is derived rigorously, providing a means to convert between the results of the two approaches, enabling designers to assess individual stage performance using the entropy-based analysis and multiple stages in terms of mechanical work potential, by using the same reference pressure.

Numerical analysis of inter-panel pillars in the bump prone conditionals of the Alardinskaya mine

The purpose of the paper is to substantiate the width of the barrier and yield pillars for the application of a new seam development scheme in the conditions of the Alardinskaya mine (Russia). The Alardinskaya mine develops gas-bearing coal seams that are prone to spontaneous combustion and are hazardous due to rock bumps, which leads to frequent accidents. The analysis of the world experience of mining seams being hazardous to rock bumps showed that safe mining with longwalls can be provided by a system of inter-panel pillars: very wide barrier pillar and two yield pillars. Numerical modeling using the finite element method was carried out to assess the possibility of reducing the barrier pillar width in order to decrease the volume of coal losses in the subsoil. The model of rock massif was created in Ansys mechanical software. Numerical modeling of the longwall panel development with longwalls was carried out at various widths of broad and yield pillars. The analysis outcomes of the vertical stresses diagrams in the seams are presented for different parts of the longwall panel. The rational parameters of the pillar system, ensuring the minimization of the reference pressure influence from the previously worked-out column and the reference pressure of the operating longwall, are determined as a result of numerical analysis. The conclusion is made about the expediency of the technological scheme application proposed by the authors in the conditions of the Alardinskaya mine to reduce the endogenous fire hazard and the danger of rock bumps.

Detection of Na in WASP-21b’s lower and upper atmosphere

Optical transmission spectroscopy provides crucial constraints on the reference pressure levels and scattering properties for the atmospheres of hot Jupiters. For certain planets, where alkali atoms are detected in the atmosphere, their line profiles could serve as a good probe to link upper and lower atmospheric layers. The planet WASP-21b is a Saturn-mass hot Jupiter orbiting a thick-disk star, with a low density and an equilibrium temperature of 1333 K, which makes it a good target for transmission spectroscopy. Here, we present a low-resolution transmission spectrum for WASP-21b based on one transit observed by the OSIRIS spectrograph at the 10.4 m Gran Telescopio Canarias (GTC), and a high-resolution transmission spectrum based on three transits observed by HARPS-N at Telescopio Nazinale Galileo (TNG) and HARPS at the ESO 3.6 m telescope. We performed spectral retrieval analysis on GTC’s low-resolution transmission spectrum and report the detection of Na at a confidence level of >3.5-σ. The Na line exhibits a broad line profile that can be attributed to pressure broadening, indicating a mostly clear planetary atmosphere. The spectrum shows a tentative excess absorption at the K D1 line. Using HARPS-N and HARPS, we spectrally resolved the Na doublet transmission spectrum. An excess absorption at the Na doublet is detected during the transit, and shows a radial velocity shift consistent with the planet orbital motion. We proposed a metric to quantitatively distinguish hot Jupiters with relatively clear atmospheres from others, and WASP-21b has the largest metric value among all the characterized hot Jupiters. The detection of Na both in the lower and upper atmospheres of WASP-21b reveals that it is an ideal target for future follow-up observations, providing the opportunity to understand the nature of its atmosphere across a wide range of pressure levels.

Embedded Sensing Capabilities in an FDM Printed Object

The objective of this paper is to demonstrate the flexure properties of ABS plastic in a 3D printed object as a process to enable embedded pressure sensing capabilities. Developing the potential for non-static 3D parts broadens the scope of the fused deposition modeling (FDM) process to include printing ‘smart’ objects that utilize intrinsic material properties to act as microphones, load sensors, accelerometers, etc. In order to demonstrate a strain-based pressure transducer, strain gauges were embedded either directly on top or in the middle of a flexible ABS diaphragm. Securing a strain gage directly on top of the diaphragm traced a reference pressure more closely than diaphragms with the strain gage embedded halfway into the diaphragm. To prevent temperature-related drift, an additional strain gage was suspended above the secured gage, inside the 3D printed cavity. The additional gage allowed for a half-bridge circuit in lieu of a quarter-bridge circuit, which minimized drift due to temperature change. The ABS diaphragm showed no significant signs of elastic hysteresis or nonlinear buckling. When sealed with 100% acetone, the diaphragm leaked ∼50x slower than as-printed sensors. After pressurizing and depressurizing the devices multiple times, they output pressure readouts that were consistent and repeatable for any given pressure within the operational range of 0 to 7psi. The repeatability of each of the final generation sensors indicates that ‘smart’ objects printed using an FDM process could be individually calibrated to make repeatable recordings. This work demonstrates a concept overlooked previous to now — FDM printed objects are not limited to static models, which lack dynamic motion of the part as an element of design. Altering FDM’s bottom-up process can allow for easily embedding sensing elements that result in printed objects which are functional on the mesoscale.