Optimal Estimation of Thermal Diffusivity in a Thermal Energy Transfer Problem with Heat Generation, Convection Dissipation and Lateral Heat Flow

This work focuses on determining the coefficient of thermal diffusivity in a one-dimensional heat transfer process along a homogeneous and isotropic bar, embedded in a moving fluid with heat generation. A first type (Dirichlet) condition is imposed on one boundary and a third type (Robin) condition is considered at the other one. The parameter is estimated by minimizing the squared errors where noisy observations are numerically simulated at different positions and instants. The results are evaluated by means of the relative errors for different levels of noise. In order to enhance the estimation performance, an optimal design technique is chosen to select the most informative data. Finally, the improvement of the estimate is discussed when an optimal design is used.

Open-Source FPGA Coprocessor for the Doppler Emulation of Moving Fluids

Embedded systems are nowadays employed in a wide range of application, and their capability to implement calculation-intensive algorithms is growing quickly and constantly. This result is obtained by the exploitation of powerful embedded processors that are often connected to coprocessors optimized for a particular application. This work presents an open-source coprocessor dedicated to the real-time generation of a synthetic signal that mimics the echoes produced by a moving fluid when investigated by ultrasounds. The coprocessor is implemented in a Field Programmable Gate Array (FPGA) device and integrated in an embedded system. The system can replace the complex and inaccurate flow-rigs employed in laboratorial tests of Doppler ultrasound systems and methods. This paper details the coprocessor and its standard interfaces, and shows how it can be integrated in the wider architecture of an embedded system. Experiments showed its capability to emulate a fluid flowing in a pipe when investigated by an echographic Doppler system.

Numerical visualization of drop and opening process for parachute-payload system adopting fluid–solid coupling simulation

In order to study the fluid–solid coupling dynamic characteristics of parachute-payload system during drop process and analyze the unsteady aerodynamic characteristics under finite mass opening conditions, an adaptive moving fluid mesh method is developed on the basis of the existing arbitrary Lagrangian–Eulerian (ALE) fluid–solid coupling method. The calculation results of open force and drop velocity on the C-9 parachute demonstrate the effectiveness of this method. On this basis, the effect of canopies with three different permeability on parachute-payload system motion characteristic including opening property, steady descent property and stability is studied. Comparative analysis is conducted for structures and characteristics of vortex with different canopy materials, and interference mechanism of unsteady flow for parachute-payload system in unsteady oscillation is revealed. The results show that the adaptive moving fluid mesh method can effectively eliminate restrictions of existing simulation methods for parachute-payload system and significantly reduce calculation time. For the lightweight parachute, permeability has significant effect on kinetic characteristic of parachute-payload system. Canopy with large permeability has small opening load and structural stress in opening stage. After opening, there are mainly small vortexes distributed evenly behind the canopy with good stability. However, canopy with small permeability has obvious breath behavior and oscillation in opening stage. The main vortexes periodically shed off after opening. With the change of permeability from small to large, Parachute-payload system eventually presents three steady descent modes: conical descent, gliding descent and stable vertical descent. Graphical abstract

Numerical investigation of flow field around T-shaped spur dyke in a reverse-meandering channel

In this paper the flow characteristics near around T-shape spur dyke situated in reverse meandering channel having rigid bed is simulated using Renormalization Group (RNG) turbulence model with an ANSYS 2018 Fluent software. To solve the model in 3D ways we used Navier-Stroke's equation based on principle of conservation of mass and momentum within a moving fluid. For studying the flow characteristics, Computational Fluid Dynamics ware applied with all geometric parameter and the turbulence was simulated using (RNG) equations of model. In this simulation the structured meshes are used with different diameter and diameter of meshes is high at exit channel for obtaining accuracy in result. In this study we mainly focus on effect of Froude number on flow pattern and several other characteristics like velocity distribution, flow separation, bed shear stress distribution. The final result of this research work is compare with the condition when no structure is present in the channel.

Multi-Directional Universal Energy Harvesting Ball

This paper discusses the development of a multi-directional, universal, electromagnetic energy harvester. The device is a ball consisting of two parts: a rigid spherical core with internal tubes, coils and magnets, and a flexible silicone-based shell holding a carrier fluid. The multi-directional aspect of the design comes from the device’s spherical shape. The harvester generates energy when subject to compressive force, by moving fluid through a tube, pushing a permanently magnetized ball through a coil wound around the tube. A combination of 3-D printed PLA plastic and molded silicone was used to produce a prototype. The energy harvester can be utilized in applications where there is an oscillating compression and it is not limited to certain applications due to its universal ball shape. It was tested at five different frequencies between 4–15 Hz on its four different outer sides producing electricity at a range of 17 to 44 mV.

Analysis of The Theory of Embryo Formation from Male Sperm and Lack of Attention to Female Sperm in Quranic Verses

The creation of man, especially the stages of his development in the fetus, is one of the complex issues and wonders of creation in the world. Before Islam and even years later, various views were expressed about how the fetus was originated. Based on the science of embryology, it has been proven that both man and woman are involved in the formation of the fetus. It is claimed that the phrase "a leaping drop" in the verse "He is created from a leaping drop" means a jumping water and refers to the sperm of man. Therefor the female sperm has not mentioned in fetus formation. In response, it can be said: Contrary to popular belief, one of the meanings of the phrase is "fast and moving fluid" and the word "dāfiq" (i.e. leaping) as a subject refers to the intrinsic motion of human creation material and it is considered as one of the secrets of the Qur'an. In other verses of the Holy Qur'an, the creation of man from the "a mingled sperm" is also specified, which refers to the mixing of the sperm of man and woman.