检索结果-南通市图书馆

The Application of a Smartphone in Ship Stability Experiment

在线全文

学校读者我要写书评

暂无评论

Journal of Marine Science and Application 2015年第4期14卷 406-412页

作者： Mohamed Abdelkader Djebli Benameur Hamoudi oma. imine Lahouari Adjlout Department of Maritime Engineering Faculty of Mechanical EngineeringUniversity of Sciences and Technology of Oran Mohamed Boudiaf BP 1505 E1 'Mnaouer Algeria

The inclining experiment is the only regulatory tool to assess ship stability. This experiment is a time consuming process for both real-life tests and ship model experiments. The difficulty is mainly due to a bias in the measurement of heel angle. Nowadays, digital inclinometers are available, but they are expensive. In this study, the use of a smartphone application is presented for ship inclination and rolling-period tests. The idea consists of using accelerometer and gyroscope sensors built into the current smartphones for the measurements. Therefore, some experiments are carried out on an example trawler model to exhibit the uses and advantages of this method. The obtained results are in good agreement with those provided from the pendulum method and natural roll-period test. This application is new, easy, and more accurately assesses metacentric height during the inclining and rolling-period tests.

关键词： ship stability GM-Meter inclining experiment rolling-period test smartphone accelerometer gyroscopic sensor

Hydrodynamic and Hydroacoustic Computational Prediction of Conventional and Highly Skewed Marine Propellers Operating in Non-uniform Ship Wake

在线全文

学校读者我要写书评

暂无评论

Journal of Marine Science and Application 2020年第1期19卷 28-40页

作者： S.E.Belhenniche O.imine O.K.Kinaci Naval Aero-Hydrodynamic Laboratory Marine Engineering DepartmentUSTO MB31000 OranAlgeria Aeronautics and Propulsion Systems Laboratory Mechanical Engineering DepartmentUSTO MB31000 OranAlgeria Faculty of Naval Architecture and Ocean Engineering Istanbul Technical UniversityAyazaga34349 IstanbulTurkey Department of Naval Architecture and Marine Engineering Istanbul Technical University TRNC CampusFamagusta 99520Northern Cyprus

Despite their high manufacturing cost and structural deficiencies especially in tip regions,highly skewed propellers are preferred in the marine industry,where underwater noise is a significant design ***,hydrodynamic performances should also be considered before a decision to use these propellers is *** study investigates the trade-off between hydrodynamic and hydroacoustic performances by comparing conventional and highly skewed Seiun Maru marine propellers for a noncavitating *** papers in the literature focus solely on hydroacoustic calculations for the open-water ***,propulsive characteristics are significantly different when propeller-hull interactions take *** in propulsion performance also reflect on the hydroacoustic performances of the *** this study,propeller-hull interactions were considered to calculate the noise *** than solving the full case,which is computationally demanding,an indirect approach was adopted;axial velocities from the nominal ship wake were introduced as the inlet condition of the numerical approach.A hybrid method based on the acoustic analogy was used in coupling computational fluid dynamics techniques with acoustic propagation methods,implementing the Ffowcs Williams-Hawkings(FW-H)*** hydrodynamic performances of both propellers were presented as a preliminary ***-hull interactions were included in calculations after observing good accordance between our results,experiments,and quasi-continuous method for the open-water *** the use of the time-dependent flow field data of the propeller behind a nonuniform ship wake as an input,simulation results were used to solve the FW-H equation to extract acoustic pressure and sound pressure levels for several hydrophones located in the near *** spectra results confirm that the highest values of the sound pressure levels are in the low-frequency range and the first harmonics calculated by the pres

关键词： Seiun Maru Moving reference frame Underwater acoustics Underwater noise Sound pressure level Blade passing frequency FW-H equation Hydrophones

Effects of Imposing Import Tariffs on a Country's Economic Growth-a Case Study on Malawi

在线全文

学校读者我要写书评

暂无评论

Effects of Imposing Import Tariffs on a Country's Economic G...

作者： TAPIWA RUTH NG'oma 河北大学

学位级别：硕士

There has been an ongoing debate as to whether there is any relationship betweenimposition of import tariffs and economic growth in developing countries. Thus, this paperaims at empirically and theoretically analysing the effects that imposition of import tariffs haveon economic growth in Malawi over the period of1982–2011. This relationship is examinedusing the Autoregressive Moving Average (ARIMA) model which will test the effect of animplemented import tariff policy on GDP growth.The Autoregressive Moving Average regression results reveal that there is a relationshipbetween imposed import tariffs and economic growth in Malawi, that is, a reduction in theaverage import tariff rate leads to a rise in GDP growth. These results strongly support the role,import trade can play in Malawi’s economic development. This means that by adopting goodimport tariff policies, Malawi will eventually boost domestic production hence the GDPgrowth.

关键词： Import tariffs Economic growth and Malawi Revenue Authority

OFDM-WDM LR-PON with ultra-bendable fiber for last-mile distribution of quintuple-play service

同方学位论文库评论

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

Chinese Optics Letters 2013年第8期11卷 18-23页

作者： Tiago M. F. Alves Rakesh Sambaraju Adolfo V. T. Cartaxo Anthony Ng'oma Instituto de Telecomunicao es Department of Electrical and Computer Engineering Instituto Superior Tcnico Technical University of Lisbon1049-001 Lisbon Portugal Science and Technology Department Corning Incorporated One Riverfront PlazaCorning NY 14831 USA

The provision of quintuple-play services along wavelength division multiplexed （WDM） long-reach passive optical networks （LR-PONs） employing an ultra-bendable fiber in last-mile distribution is demonstrated experimentally. Particularly, the simultaneous transmission of three 100-GHz-spaced optical channels for the provision of double sideband orthogonal frequency-division multiplexing （OFDM） wireless and wired quintuple-play services to the premises of users located at 75, 85, and 100 km away from the central office is demonstrated. The OFDM-WDM LR-PON is tested considering the last-mile fiber distribution suffering from severe bending conditions without optical dispersion compensation. The experiments are performed for a worst last-mile fiber bending case emulated by considering a Corning ClearCurve fiber experiencing 20 bends and a bend radius of 7.5 mm. All the OFDM signals received at the premises of users present error vector magnitude （EVM） levels compliant with the EVM thresholds of the corresponding standards. An EVM degradation in the OFDM signals received by each user not exceeding 0.8 dB due to the last-mile distribution fiber is achieved.

关键词： WDM PON OFDM-WDM LR-PON with ultra-bendable fiber for last-mile distribution of quintuple-play service LR

同方期刊数据库

Liver dysfunction and SARS-CoV-2 infection

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2021年第26期27卷 3951-3970页

作者： Abraham Edgar Gracia-Ramos Joel oma. Jaquez-Quintana Raúl Contreras-oma.a Moises Auron Department of Internal Medicine General HospitalNational Medical Center"La Raza"Instituto Mexicano del Seguro SocialMexico City 02990Mexico Gastroenterology Service and Department of Internal Medicine Faculty of MedicineUniversity Hospital"Dr.JoséE.González"Universidad Autónoma de Nuevo LeónMonterrey 64460Mexico Centro de Estudio e Investigación en Enfermedades Hepáticas y Toxicológicas(CEIHET) Pachuca 42184Mexico Departments of Hospital Medicine and Pediatric Hospital Medicine Cleveland ClinicClevelandOH 44195United States

Severe acute respiratory syndrome coronavirus 2 infection is the cause of coronavirus disease 2019(COVID-19),which predominantly affects the respiratory system;it also causes systemic and multi-organic *** damage is among the main extrapulmonary ***-19-associated liver injury is defined as any liver damage occurring during the disease course and treatment of COVID-19 in patients with or without pre-existing liver disease,and occurs in approximately one in five *** liver test results have been associated with a more severe course of COVID-19 and other complications,including *** linking COVID-19 to liver injury are *** consideration should be made for patients with pre-existing liver disease,such as metabolic dysfunction-associated fatty liver disease,chronic liver disease due to viral or autoimmune disease,liver transplant carriers,or cirrhosis,given the risk for more severe *** manuscript summarizes the current lines of evidence on COVID-19-associated liver injury regarding pathophysiology,clinical significance,and management in both patients with or without preexisting liver disease,to facilitate clinicians’access to updated information and patient ***,we mention the ideas and recommendations to be considered for future research.

关键词： SARS-CoV-2 Coronavirus COVID-19 Liver Liver diseases Liver failure Liver injury Cirrhosis

Numerical Simulation of the Flow around Marine Propeller Series

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Physical Science and Application 2016年第3期6卷 55-61页

作者： Djahida Boucetta and oma. imine Department of Marine Engineering Faculty of Mechanical Engineering University of Sciences and Technology of Oran B.P 1505USTO Oran Algeria

The objective of marine propeller design optimization study is to obtain a propeller with minimum power absorption, maximum efficiency and good materials resistance. In this study, results of numerical simulation carried out on the flow around a conventional marine propeller are presented. The investigation focused on the aspects related to the influence of skew magnitude, thickness and blade number on the propeller performances. First, open water performances of a conventional propeller model DTMB 4148 was estimated using RANS （Reynolds Averaged Navier-Stokes） method. The flow around rotating propeller model was analyzed in the steady state using RANS approach of the commercial CFD （computational fluid dynamics） code fluent. The results provide good agreement with literature data. Numerical results show that the number of blades has an influence on the open water performances of marine propellers. It＇s noticed that the best propeller has four or five blades from only the hydrodynamic aspect. The thickness blade effect has been studied for the same propeller model and compared to the blade with three different thickness values. Results of the calculation show that the blade thickness increases moderately the propeller efficiency. Finally, numerical simulation is performed to study the magnitude skew effect on the propeller blade performance, so three different models were generated. The results of the simulation show that the skew distribution has a positive effect on the open water performances of the marine propellers.

关键词： Marine propeller CFD simulation blade number blade thickness skew magnitude open water performances.

Dynamics of Nerve Pulse Propagation in a Weakly Dissipative Myelinated Axon

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Modern Physics 2016年第10期7卷 1166-1180页

作者： Nkeh oma.Nfor Mebu Tatason Mokoli Complex Systems and Theoretical Biology Group Laboratory of Research on Advanced Materials and Nonlinear Science(LaRAMaNS) Department of Physics Faculty of ScienceUniversity of Buea Buea Cameroon Laboratory of Research on Advanced Materials and Nonlinear Science (LaRAMaNS) Department of Physics Faculty of Science University of Buea Buea Cameroon

We analytically derived the complex Ginzburg-Landau equation from the Liénard form of the discrete FitzHugh Nagumo model by employing the multiple scale expansions in the semidiscrete approximation. The complex Ginzburg-Landau equation now governs the dynamics of a pulse propagation along a myelinated nerve fiber where the wave dispersion relation is used to explain the famous phenomena of propagation failure and saltatory conduction. Stability analysis of the pulse soliton solution that mimics the action potential fulfills the Benjamin-Feir criteria for plane wave solutions. Finally, results from our numerical simulations show that as the dissipation along the myelinated axon increases, the nerve impulse broadens and finally degenerates to front solutions.

关键词： Ginzburg-Landau Equation Liénard Form Fitz Hugh Nagumo Model Semidiscrete Approximation Saltatory Conduction Benjamin-Feir Criteria Dissipation

Localized nonlinear waves in a myelinated nerve fiber with self-excitable membrane

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2023年第2期32卷 150-162页

作者： Nkeh oma.Nfor Patrick Guemkam Ghomsi Francois Marie Moukam Kakmeni Department of Physics HTTC BambiliUniversity of BamendaP.P.Box 39 BambiliCameroon Complex Systems and Theoretical Biology Group Laboratory of Research on Advanced Materials and Nonlinear Science(LaRAMaNS)Department of PhysicsFaculty of ScienceUniversity of BueaP.O.Box 63 BueaCameroon

We systematically study the evolution of modulated nerve impulses in a myelinated nerve fiber, where both the ionic current and membrane capacitance provide the necessary nonlinear feedbacks. This is achieved by using a perturbation technique, in which the Liénard form of the modified discrete Fitzhugh–Nagumo equation is reduced to the complex Ginzburg–Landau amplitude equation. Three distinct values of the capacitive feedback parameter are considered. At the critical value of the capacitive feedback parameter, it is shown that the dynamics of the system is governed by the dissipative nonlinear Schr?dinger equation. Linear stability analysis of the system depicts the instability of plane waves,which is manifested as burst of modulated nerve impulses that fulfills the Benjamin–Feir criteria. Variations of the capacitive feedback parameter generally influences the plane wave stability and hence the type of wave profile identified in the neural network. Results of numerical simulations mainly confirm the propagation, collision, and annihilation of nerve impulses in the myelinated axon.

关键词： myelinated nerve Fitzhugh–Nagumo capacitive feedback parameter Ginzburg–Landau collision annihilation

Letter to the Editor concerning:Gallbladder perforation:A single-center experience in north India and a step-up approach for management

在线全文

学校读者我要写书评

暂无评论

Hepatobiliary & Pancreatic Diseases International 2022年第6期21卷 617-618页

作者： Hermilo Jeptef Angeles-Mar Mariano Garcia-Camp RodrigoEnrique Elizondo-oma.a Santos Guzmán-López Javier Humberto Martinez-Garza Alejandro Quiroga-Garza Universidad Autonoma.de Nuevo Leon School of MedicineHuman Anatomy DepartmentMonterreyNuevo León CP 64460México Universidad Autonoma.de Nuevo Leon School of MedicinePlataforma INVEST-KER Unito Mayo Clinic(KER Unit Mexico)MonterreyNuevo LeónMéxico General Surgery Division Instituto Mexicano del Seguro SocialMonterreyNuevo LeónMéxico

To the Editor:We sincerely applaud the work done by Gupta et al.,in which they analyzed a single-center experience regarding gallbladder per-foration(GBP)management[1].Currently,there is a lack of cohort studies to adequately describe the approach strategies and man-agement for this pathology,with international guidelines making ambiguous recommendations[2,3].Their study stratified GBP types and provided details regarding clinical presentation,comorbidities,preoperative diagnosis,etiology,imaging techniques,and surgical *** study reported a high conversion rate when a la-paroscopic approach was attempted for cholecystectomy.

关键词： diagnosis concerning approach