Proračun strukturnih dimenzija pramčanog i krmenog dijela broda izloženim valnim udarnim opterećenjima prema pravilima klasifikacijskih društava

Cilj ovog rada je istražiti kako različiti pristupi dvaju klasifikacijskih društava, Det \Norske Veritas i Lloyd's Register, utječu na dimenzije strukturnih elemenata. Kroz uvod i drugo poglavlje je pobliže objašnjena sama pojava udaranja u valove (eng. slamming). U trećem poglavlju su ukratko objašnjene razlike u pristupima tom problemu ovih dvaju klasifikacijskih društava. U četvrtom poglavlju je predstavljena izabrana forma trupa broda te se kroz peto, šesto i sedmo poglavlje proračunavaju glavne veličine potrebne za rješavanje ovog problema. Kroz studiju osjetljivosti u osmom poglavlju se istražuje koliko pojedini parametri utječu na ovu pojavu. U zaključku je konačni komentar dobivenih rezultata i utjecaja ispitivanih parametara

Response and Dynamical Stability of Oscillators with Discontinuous or Steep First Derivative of Restoring Characteristic

Response and dynamical stability of oscillators with discontinuous or steep first derivative of restoring characteristic is considered in this paper. For that purpose, a simple single-degree-offreedom system with piecewise-linear force-displacement relationship subjected to a harmonic force excitation is analysed by the method of piecing the exact solutions (MPES) in the time domain and by the incremental harmonic balance method (IHBM) in the frequency domain. The stability of the periodic solutions obtained in the frequency domain by IHBM is estimated by the Floquet-Lyapunov theorem. Obtained frequency response characteristic is very complex and includes multi-frequency response for a single frequency excitation, jump phenomenon, multi-valued and non-periodic solutions. Determining of frequency response characteristic in the time domain by MPES is exceptionally time consuming, particularly inside the frequency ranges of co-existence of multiple stable solutions. In the frequency domain, IHBM is very efficient and very well suited for obtaining wide range frequency response characteristics, parametric studies and bifurcation analysis. On the other hand, neglecting of very small harmonic terms (which in-significantly influence the r.m.s. values of the response and are very small in comparison to other terms of the spectrum) can cause very large error in evaluation of the eigenvalues of the monodromy matrix, and so they can lead to incorrect prediction of the dynamical stability of the solution. Moreover, frequency ranges are detected inside which the procedure of evaluation of eigenvalues of the monodromy matrix does not converge with increasing the number of harmonics included in the supposed approximate solution

Effect of a carbohydrate and branched-chain amino acid beverage on skill performance in soccer players

The present studies investigated the effect of a carbohydrate and branched-chain amino acid (CHO+BCAA) beverage on cognitive and sport specific skill performance in soccer players. [This is an excerpt from the abstract. For the complete abstract, please see the document.

Response and Dynamical Stability of Oscillators with Discontinuous or Steep First Derivative of Restoring Characteristic

Response and dynamical stability of oscillators with discontinuous or steep first derivative of restoring characteristic is considered in this paper. For that purpose, a simple single-degree-of-freedom system with piecewise-linear force-displacement relationship subjected to a harmonic force excitation is analysed by the method of piecing the exact solutions (MPES) in the time domain and by the incremental harmonic balance method (IHBM) in the frequency domain. The stability of the periodic solutions obtained in the frequency domain by IHBM is estimated by the Floquet-Lyapunov theorem. Obtained frequency response characteristic is very complex and includes multi-frequency response for a single frequency excitation, jump phenomenon, multi-valued and non-periodic solutions. Determining of frequency response characteristic in the time domain by MPES is exceptionally time consuming, particularly inside the frequency ranges of co-existence of multiple stable solutions. In the frequency domain, IHBM is very efficient and very well suited for obtaining wide range frequency response characteristics, parametric studies and bifurcation analysis. On the other hand, neglecting of very small harmonic terms (which in-significantly influence the r.m.s. values of the response and are very small in comparison to other terms of the spectrum) can cause very large error in evaluation of the eigenvalues of the monodromy matrix, and so they can lead to incorrect prediction of the dynamical stability of the solution. Moreover, frequency ranges are detected inside which the procedure of evaluation of eigenvalues of the monodromy matrix does not converge with increasing the number of harmonics included in the supposed approximate solution

Numeričke simulacije dinamike slijetanja zrakoplova

Numerical simulation procedures for landing dynamics of large transport aircraft are briefly presented. Developed numerical procedures allow for determination of dynamic response of landing aircraft for different flight and touch-down parameters. A non-linear dynamic model of landing aircraft, which serves as a basis for computational procedures, is synthesised by modelling of aircraft structural subsystems using a multibody dynamics approach. A dynamic model with variable kinematical structures includes discontinuous dynamics of landing gear oleo-pneumatic shock-absorber with friction and hydraulic/thermodynamic processes. Non-linear tire contact dynamics and unilateral dynamics of nose gear elastic leg assembly is modelled as well. The longitudinal and lateral aerodynamic loads are estimated by considering various aircraft system configurations (landing gears in “up’’ and “down’’ position, different control surfaces in active/inactive modes). A mathematical model is derived as a differential- algebraic (DAE) system. The developed numerical tools are modularly shaped and efficient numerical integration methods as well as original procedures for MBS constraint stabilization are applied for dynamic response determination. On the basis of the presented model, dynamic simulations of landing cases of large transport aircraft were performed for different initial descent velocities with focus on determination of dynamical loading of main landing gear assembly.U ovom radu ukratko su opisane numeričke simulacijske procedure za dinamiku slijetanja velikog transportnog zrakoplova. Razvijene numeričke procedure omogućavaju određivanje dinamičkog odziva zrakoplova prilikom slijetanja i to za različite parametre leta i slijetanja. Nelinearni dinamički model zrakoplova pri slijetanju, kao osnova računalnih procedura, dobiven je sintezom modela konstrukcijskih podsustava zrakoplova primjenom mehaničkih i matematičkih algoritama dinamike konstrukcijskih sustava. Dinamički model zrakoplova s varijabilnom kinematičkom topologijom obuhvaća diskontinuiranu dinamiku oleo-pneumatske elastične noge glavnog podvozja s uključenim termodinamičkim/hidrauličnim procesima, kontaktnu dinamiku gume te nelinearnu unilateralnu dinamiku elastične noge nosnog kotača. Uzdužna i bočna aerodinamička opterećenja procijenjena su za različite konfiguracije letjelice (uvučeno/izvučeno podvozje, izvučena/uvučena zakrilca te otkloni ostalih upravljačkih površina). Matematički model izveden je kao sustav diferencijalno-algebarskih jednadžbi (DAE). Razvijeni računalni alati oblikovani su modularno te su za potrebe određivanja dinamičkog odziva primijenjene efikasne metode numeričke integracije, kao i originalne procedure stabilizacije dinamičkih odziva konstrukcijskih sustava sa složenim kinematičkim ograničenjima. Temeljem izloženog modela provedene su dinamičke simulacije slijetanja velikog transportnog zrakoplova i to za različite brzine spuštanja s fokusom na određivanje dinamičkog opterećenja glavnog podvozja

Decreased periferal blood dendritic cells in multiple Myeloma: The potential role of IL-6 and Beta-2-Microglobulin

Introduction: Several studies demonstrate the presence of quantitative and functional abnormalities in the dendritic cell (DC) subsets in patients with multiple myeloma (MM). The inhibitory effect of IL-6, TGF-!, IL-10 and beta-2-microglobuline (beta-2-MG) is highly suspected.Purpose: The aim of the study was to evaluate the myeloid and plasmacytoid dendritic cells (MDC and PDC) in newly diagnosed patients with MM in correlation with various biological markers.Materials and Methods: Thirty patients with newly diagnosed MM were included in the study. All the laboratory parameters were obtained at the time of diagnosis. Three colour flow cytometry with ILT3/lin/CD11c was used for the detection of the two peripheral blood dendritic cell (PBDC) subsets. The plasma level of IL6 was detected by ELISA (Standard Curve Range: 2-200pg/ml); the beta-2-MG- by the immunoturbidimetric test.Results: The median age of patients was 61.5 years (36-89). The mean M-protein concentration was 46.5±16.2 g/l. IgG kappa was detected in 15 patients, IgG lambda-in 4, IgA kappa-in 7, IgA lambda-in 3. The mean level of beta-2-MG was 7.0±5.7mg/l (1.82-22.49 mg/l ); beta-2-MG was used to determine the stage according to the ISS. The mean level of IL6 was 27.73±21.47pg/ml (4.6-72.5 pg/ml). The percentage of MDC and PDC was significantly lower in the periferal blood of patients with MM in comparison to healthy subjects (0.08%±0.09% vs 0.21%±0.02% and 0.04%±0.03% vs 0.16%±0.01%, respectively). A statistically significant difference was found between the percentage of MDC and PDC in the different stages. There was a negative correlation between MDC and PDC and the levels of beta-2-MG (p=0.02 and p=0.02), as well as between MDC and the IL6 levels (p=0.04). No correlation was found between MDC, PDC, levels of M-protein and the type of paraprotein.Conclusion: Our results demonstrate the relationship between peripheral blood DC, IL6 and beta-2-MG and confirm the published data for the inhibitory effect of the two factors on DC differentiation and maturation in vitro. The monitoring of beta-2-MG and IL6 may have clinical implication as a predictor of the immune system status as well as for the yield of harvested DCs for vaccination

mFrame: An Application Framework for Mobile Resource-constrained Computing Environments

The component and architectural design reuse value of application frameworks enables higher productivity, faster turn-around time, and reduced cost when compared with the traditional development approaches. Because of the constrained nature of mobile devices, the application frameworks for such a computing environment have to provide a simple and lightweight implementation while still maintaining their flexibility and reusability value. This paper presents mobile Framework (mFrame) application framework that can be used for deploying software applications to compact mobile devices such as cellular phones, personal digital assistants (PDA), global positioning systems (GPS) etc. It introduces a queuing and service layer architecture that provides simple data exchange mechanism between the presentation components and local and remote business services. Compact mobile devices using this architecture will be able to handle network disconnections, because the requests will be saved; and information will be exchanged with the remote services upon reconnection

Simple dynamic model of wind turbine tower with experimental verification

The main goal in designing the wind turbine is ensuring structural safety and optimal operational performance. Key aspects to be addressed are: long design life, sensitivity of structure to vibration and resonance, non-deterministic wind loads with significant time variations and micro-location dependence. In order to achieve these goals, a simple dynamic lumped-mass model of a conic tubular steel wind turbine tower has been developed in this paper. The tower stiffness matrix is determined by considering the stiffness of a cantilever beam with variable cross-section, and lumped masses for each conical segment are determined in such a way that the centres of gravity of conical segments match their actual position in the structure. There is a very good agreement between the measured field data and the results obtained by the developed simple numerical model