Buckling Properties of Water-Drop-Shaped Pressure Hulls with Various Shape Indices Under Hydrostatic External Pressure

The water-drop-shaped pressure hull has a good streamline,which has good application prospect in the underwater observatory.Therefore,this study conducted analytical,experimental and numerical investigation of the buckling properties of water-drop-shaped pressure hulls under hydrostatic pressure.A water-drop experiment was conducted to design water-drop-shaped pressure hulls with various shape indices.The critical loads for the water-drop-shaped pressure hulls were resolved by using Mushtari’s formula.Several numerical simulations including linear buckling analysis and nonlinear buckling analysis including eigenmode imperfections were performed.The results indicated that the critical loads resolved by Mushtari's formula were in good agreement with the linear buckling loads from the numerical simulations.This formula can be extended to estimate the buckling capacity of water-drop-shaped pressure hulls.In addition,three groups of pressure hulls were fabricated by using stereolithography,a rapid prototyping technique.Subsequently,three groups of the pressure hulls were subjected to ultrasonic measurements,optical scanning,hydrostatic testing and numerical analysis.The experimental results were consistent with the numerical results.The results indicate that the sharp end of the water-drop-shaped pressure hulls exhibited instability compared with the blunt end.This paper provides a new solution to the limitations of experimental studies on the water-drop-shaped pressure hulls as well as a new configuration and evaluation method for underwater observatories.

Co-seismic Water Level and Temperature Responses of Some Wells to Far-Field Strong Earthquakes and Their Mechanisms

The observation of water temperature in deep wells has been carried out for more than 20 years in China.However,study on the mechanism of water temperature response to earthquakes is inadequate.During the study of the co-seismic response characteristics of water level and temperature in 121 wells within the China subsurface fluid monitoring network at the time of the December 26,2004,M-S8.7 Indonesia earthquake,we found regular response characteristics,that is,when the water level in a deep well oscillates,the water temperature in the same well will mostly experience a cycle from dropping to restoration at the same time.The process will continue for dozens of minutes to several hours.In order to confirm the observed phenomenon,we collected the digital water level and temperature observation data for 39 far-field strong earthquakes from the Tangshan well in Hebei Province(with the data set beginning in 2001).The same response characteristics were observed.Based on the analysis of the influencing factors that may cause the water temperature drop,the authors suggest the gas escape mechanism for co-seismic water temperature drop and posit two main factors that influence the water temperature drop during the process of gas escape.Finally,the authors provide a rational explanation of some observed phenomena based on the mechanism.

The corrosive behaviors of GI and IF steel sheets in salt water drops

The corrosive behaviors of hot-dip galvanized steel （G I） sheets and the corresponding interstitial free （IF） steel base sheets for use in automobiles were investigated by the classical salt water drop （SWD） test at room temperature. The corrosive processes and products were observed and analyzed through morphological observation, a scanning electronic microscope （SEM） and an energy dispersive spectrum （EDS）. The results show that the anodic and cathode sites can be distinguished clearly during and after the test. The propagation of rusting, and the color, distribution and composition of the final corrosive products of the two kinds of materials are quite different. The SWD corrosive mechanisms of steel with and without galvanized coating are both discussed in this paper.

Rear-Surface Deformation of a Water Drop in Aero-Breakup of Shear Mode

Deformation of water drops in shock-induced high-speed flows is investigated with a focus to the influence of primitive flow parameters on the rear-surface deformation features. Two typical deformation patterns are discovered through high-speed photography. A simple equation to evaluate the radial acceleration of the drop surface is derived. The combined use of this equation and outer flow simulation makes it possible for us to reconstruct the profiles of the early deformed drops. The results agree well with the experiments. Further analysis shows that the duration of flow establishment with respect to the overall breakup time shapes the rear side profile of the drop. Thereby the ratio of the two times, expressed as the square root of the density ratio, appears to be an effective indicator of the deformation features.

Novel Computer-Aided Diagnosis System for the Early Detection of Alzheimer’s Disease

Aging is a natural process that leads to debility,disease,and dependency.Alzheimer’s disease(AD)causes degeneration of the brain cells leading to cognitive decline and memory loss,as well as dependence on others to fulfill basic daily needs.AD is the major cause of dementia.Computer-aided diagnosis(CADx)tools aid medical practitioners in accurately identifying diseases such as AD in patients.This study aimed to develop a CADx tool for the early detection of AD using the Intelligent Water Drop(IWD)algorithm and the Random Forest(RF)classifier.The IWD algorithm an efficient feature selection method,was used to identify the most deterministic features of AD in the dataset.RF is an ensemble method that leverages multiple weak learners to classify a patient’s disease as either demented(DN)or cognitively normal(CN).The proposed tool also classifies patients as mild cognitive impairment(MCI)or CN.The dataset on which the performance of the proposed CADx was evaluated was sourced from the Alzheimer’s Disease Neuroimaging Initiative(ADNI).The RF ensemble method achieves 100%accuracy in identifying DN patients from CN patients.The classification accuracy for classifying patients as MCI or CN is 92%.This study emphasizes the significance of pre-processing prior to classification to improve the classification results of the proposed CADx tool.

Failure Prediction for Scientific Workflows Using Nature-Inspired Machine Learning Approach

Scientific workflows have gained the emerging attention in sophisti-cated large-scale scientific problem-solving environments.The pay-per-use model of cloud,its scalability and dynamic deployment enables it suited for executing scientific workflow applications.Since the cloud is not a utopian environment,failures are inevitable that may result in experiencingfluctuations in the delivered performance.Though a single task failure occurs in workflow based applications,due to its task dependency nature,the reliability of the overall system will be affected drastically.Hence rather than reactive fault-tolerant approaches,proactive measures are vital in scientific workflows.This work puts forth an attempt to con-centrate on the exploration issue of structuring a nature inspired metaheuristics-Intelligent Water Drops Algorithm(IWDA)combined with an efficient machine learning approach-Support Vector Regression(SVR)for task failure prognostica-tion which facilitates proactive fault-tolerance in the scheduling of scientific workflow applications.The failure prediction models in this study have been implemented through SVR-based machine learning approaches and the precision accuracy of prediction is optimized by IWDA and several performance metrics were evaluated on various benchmark workflows.The experimental results prove that the proposed proactive fault-tolerant approach performs better compared with the other existing techniques.

Characteristics of Water Infiltration in Layered Water-Repellent Soils

Water-repellent(WR) soil greatly influences infiltration behavior. This research determined the impacts of WR levels of silt loam soil layer during infiltration. Three column scenarios were utilized, including homogeneous wettable silt loam or sand, silt loam over sand(silt loam/sand), and sand over silt loam(sand/silt loam). A 5-cm thick silt loam soil layer was placed either at the soil surface or 5 cm below the soil surface. The silt loam soil used had been treated to produce different WR levels, wettable, slightly WR, strongly WR, and severely WR. As the WR level increased from wettable to severely WR, the cumulative infiltration decreased. Traditional wetting front-related equations did not adequately describe the infiltration rate and time relationships for layered WR soils. The Kostiakov equation provided a good fit for the first infiltration stage. Average infiltration rates for wettable, slightly WR, strongly WR, and severely WR during the 2 nd infiltration stage were 0.126, 0.021, 0.002, and 0.001 mm min^(-1) for the silt loam/sand scenario,respectively, and 0.112, 0.003, 0.002, and 0.000 5 mm min^(-1) for the sand/silt loam scenario, respectively. Pseudo-saturation phenomena occurred when visually examining the wetting fronts and from the apparent changes in water content(?θ_(AP)) at the slightly WR,strongly WR, and severely WR levels for the silt loam/sand scenario. Much larger ?θAPvalues indicated the possible existence of finger flow. Delayed water penetration into the surface soil for the strongly WR level in the silt loam/sand scenario suggested negative water heads with infiltration times longer than 10 min. The silt loam/sand soil layers produced sharp transition zones of water content. The WR level of the silt loam soil layer had greater effects on infiltration than the layer position in the column.

Effects of dynamic deformation of pendant water drops on the electric field between hollow porcelain insulator sheds under extreme rainfall

Hollow porcelain insulators in substations are frequently confronted with rain flashovers under extreme rainfall.This study aims to investigate the spatial and temporal variation of electric fields between hollow porcelain insulator sheds affected by dynamic deformation of pendant water drops and effects of the dimensionless number of fluids,the Weber number(We)and the electric Bond number(BoE),on it for influencing factors'analysis.Flow‐electric field coupling simulations were carried out to compute the magnitude and the position of AC electric fields between the sheds.The results show that the maximum electric field at a point in time(Etmax)increases significantly after the breakup of the pendant water drop,and its position alters accordingly.For low We and BoE,the global maximum electric field(Egmax)increases with increasing We and BoE,respectively.It is much closer to the adjacent sheds and occurs later than Etmax at the breakup of the pendant water drop(Ebmax).By contrast,Egmax decreases in different degrees at high We and BoE,respectively.There is little difference between Egmax and Ebmax in the position and the occurring time.The influence mechanism on the maximum electric field and discharges and the relationship between discharges induced by the pendant water drop and rain flashover are discussed.

ON THE ICE NUCLEATION BY CONTACT ON THE INNER AND OUTER LAYER OF A WATER DROP

Nucleation of ice by contact takes place when an aerosol particle collides with asurface of supercooled water drop.Aerosol particle may either bounce off the watersurface or be captured on it.McCully et al.(1956) and Rosinski et al.(1963) have shownthat capture of hydrophilic particles was four times larger than of hydrophobic ones.Hydrophobic aerosol particles will nucleate ice preferentially during the brief time ofcontact when they bounce off the surface.Patricles that become captured on the surfacewill float and produce clusters that may nucleate ice at some later time (delayed on surface

UNIFIED MODEL FOR SPLASH DROPLETS AND SUSPENDED MIST OF ATOMIZED FLOW

In this article, the unified mathematical model for splash droplets and suspended mist of atomized flow was established, which classifies the atomized sources into the splash source and the suspended source. For the splash source, the Lagrangian method was used to simulate the random motion of splash water droplets, and for the suspended source the theory of air-water two-phase flow was used to simulate the mist flow moving in particle clouds. The rainfall intensity of the atomized flow was obtained by summarizing the rainfall intensities relative to the above two types of atomized sources. Both experimental data and prototype observation data were used for the verification of the mathematical model. For both the distribution of rainfall intensity, and the outer edge of the atomized flow, the simulation results are in agreement with the experimental data or prototype observation data.

Reclamation of oil-induced soil hydrophobicity in the hyper-arid Evrona Nature Reserve,southern Israel

Two oil spills occurred in the Evrona Nature Reserve(southern Israel),in 1975 and 2014.This oil contamination induced highly persistent soil hydrophobicity.The objective of this study was to investigate the decrease in oil-induced soil hydrophobicity under different environmental conditions and to assess the relationship between the hydrophobicity and hydrocarbon content.A laboratory incubation experiment was conducted over 1.5 years to monitor the soil hydrophobicity and total hydrocarbon concentration under different environmental conditions.We hypothesized that the addition of water(20% or 50% saturation),nutrients,and biosurfactants can accelerate the reduction in hydrophobicity and decomposition of hydrocarbons.Water drop penetration time and molarity of ethanol droplet tests were used to assess soil hydrophobicity.In parallel,alkane composition and total petroleum hydrocarbons were evaluated to indicate oil attenuation.The addition of water,nutrients,and biosurfactants resulted in a concomitant reduction in hydrophobicity and hydrocarbon concentration of varying degrees,exhibiting enhanced degradation and hydrophobicity reduction observed in treatments to which nutrients and biosurfactants were added.At the end of the incubation,however,soil hydrophobicity in all treatments remained severe,even though total petroleum hydrocarbon removal was fairly high and reached 40%–80%in the treatments to which water with or without nutrients and/or surfactants was added.

Improved offline multi-objective routing and wavelength assignment in optical networks

Optical networks act as a backbone for coming generation high speed applications.These applications demand a very high bandwidth which can be exploited with the use of wavelength division multiplexing(WDM)technology.The issue of setting light paths for the traffic demands is routing and wavelength assignment(RWA)problem.Based on the type of traffic patterns,it can be categorized as offline or online RWA.In this paper,an effective solution to offline(static)routing and wavelength assignment is presented considering multiple objectives simultaneously.Initially,the flower pollination(FP)technique is utilized.Then the problem is extended with the parallel hybrid technique with flower pollination and intelligent water drop algorithm(FPIWDA).Further,FPIWD is hybrid in parallel with simulated annealing(SA)algorithm to propose a parallel hybrid algorithm FPIWDSA.The results obtained through extensive simulation show the superiority of FPIWD as compared to FP.Moreover,the results in terms of blocking probability with respect to wavelengths and load of FPIWDSA are more propitious than FP and FPIWD.