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Space Exploration - - Bog - Nova Science Publishers Inc - Plusbog.dk

Space Exploration - - Bog - Nova Science Publishers Inc - Plusbog.dk

Human spaceflight at NASA began in the 1960s with the Mercury and Gemini programs leading up to the Apollo moon landings. After the last lunar landing, Apollo 17, in 1972, NASA shifted its attention to low earth orbit operations with human spaceflight efforts that included the Space Shuttle and International Space Station programs through the remainder of the 20th century. Exploration of our solar system has brought great knowledge to our Nations scientific and engineering community over the past several decades. As we expand our visions to explore new, more challenging destinations, we must also expand our technology base to support these new missions. NASAs Space Technology Mission Directorate is tasked with developing these technologies for future mission infusion and continues to seek answers to many existing technology gaps.

DKK 718.00
1

Thiols - - Bog - Nova Science Publishers Inc - Plusbog.dk

Thiols - - Bog - Nova Science Publishers Inc - Plusbog.dk

The thiol (-SH) is an essential functional group in the biological system. The -SH groups play a catalytic and structural role in enzymes and proteins that participate in the defense against reactive oxygen species, detoxification, signal transduction, energy production, apoptosis, and other biological functions. In this compilation, the authors begin by exploring how the inorganic and organic forms of mercury interact with these macromolecules. In the following study, thiol-methacrylate networks based on a tetrafunctional thiol and dimethacrylate monomers were prepared by both photopolymerization and amine-catalyzed Michael addition reaction. The progress of the polymerization reaction was monitored by FTIR and Raman spectroscopy. The cured materials were characterized by measuring the glass transition temperature, the flexural modulus, and the compressive strength. In the closing study, a novel and efficient protocol is presented which has been developed for the synthesis of symmetrical disulfides from thiols using thionyl chloride as the sole oxidizing agent at ambient conditions. Also, a tentative mechanism has been reported for the reaction.

DKK 624.00
1

Numerical Modeling, Prediction of Ship Maneuvering and Hydrodynamics during Inland Waterway Transport - Peng Du - Bog - Nova Science Publishers Inc -

Numerical Modeling, Prediction of Ship Maneuvering and Hydrodynamics during Inland Waterway Transport - Peng Du - Bog - Nova Science Publishers Inc -

In this work, ship hydrodynamics during inland waterway transport and ship manoeuvring are investigated using CFD (Computational Fluid Dynamics) based on OpenFoam. Validation and verification studies are carried out for the mesh convergence, time step convergence, sensitivity to turbulence models and dynamic mesh techniques. A quaternion-based 6DoF motion solver is implemented for the trim and sinkage predictions. Environmental effects on several inland vessels (convoy 1, convoy 2, tanker) are studied using the validated numerical models. Three important aspects, the confinement effect of the waterway, head-on encounter, and ship-bridge pile interaction are simulated. The testing conditions cover a wide range, including various channel dimensions, water depths, ship draughts and speeds. The ship resistance, wave pattern, Kelvin angle and wave elevation at specific positions are investigated as functions of these parameters. Ship manoeuvring is investigated using virtual captive model tests based on the MMG (Mathematical Maneuvering Group) model. An actuator disk is implemented to replace the real propeller. Open water test, rudder force test, OTT (Oblique Towing Tank test) and CMT (Circular Motion Test) of a KVLCC2 model are carried out to obtain the hydrodynamic coefficients of the propeller, rudder and ship hull. Using the obtained coefficients, system-based manoeuvring simulations are carried out and validated using the free running test data. These studies reproduce real ship tests and thus prove the validity of our numerical models. As a result, the numerical solver is promising in ship hydrodynamics and marine engineering simulations.

DKK 718.00
1

Understanding Quaternions - - Bog - Nova Science Publishers Inc - Plusbog.dk

Understanding Quaternions - - Bog - Nova Science Publishers Inc - Plusbog.dk

Quaternions are members of a noncommutative division algebra first invented by William Rowan Hamilton. They form an interesting algebra where each object contains 4 scalar variables, instead of Euler angles, which is useful to overcome the gimbal lock phenomenon when treating the rotation of objects. This book is about the mathematical basics and applications of quaternions. The first four chapters mainly concerns the mathematical theories, while the latter three chapters are related with three application aspects. It is expected to provide useful clues for researchers and engineers in the related area. In detail, this book is organized as follows: In Chapter 1, mathematical basics including the quaternion algebra and operations with quaternions, as well as the relationships of quaternions with other mathematical parameters and representations are demonstrated. In Chapter 2, how quaternions are formulated in Clifford Algebra, how it is used in explaining rotation group in symplectic vector space and parallel transformation in holonomic dynamics are presented. In Chapter 3, the wave equation for a spin 3/2 particle, described by 16-component vector-bispinor, is investigated in spherical coordinates. In Chapter 4, hyperbolic Lobachevsky and spherical Riemann models, parameterized coordinates with spherical and cylindric symmetry are studied. In Chapter 5, ship hydrodynamics with allowance of trim and sinkage is investigated and validated with experiments. In Chapter 6, the ballast flying phenomenon based on Discrete Discontinuous Analysis is presented. In Chapter 7, a numerical study is proposed to analyze the effect of the caisson sliding subjected to a hydrodynamic loading in the stability of the rear side of the rubble mound breakwater.

DKK 718.00
1