bluuebunny/crossref_metadata_2025 huggingface dataset:
Analytical Solution and Experimental Study of Effective Young's Modulus of Selective Laser Melting-Fabricated Lattice Structure With Triangular Unit Cells
Authors: Niu Jie , Choo Hui Leng , Sun Wei , Mok Sui Him
Published: July 2018

Research on materials, design, processing, and manufacturability of parts produced by additive manufacturing (AM) has been investigated significantly in the past. However, limited research on tensile behavior of cellular lattice structures by AM was carried out. In this paper, effective tensile Young's modulus, E*, of triangular lattice structures was determined. Firstly, analytical solution was derived based on Euler–Bernoulli beam theory. Then, numerical results of E* were obtained by finite element analysis (FEA) for triangular lattice structures classified by three shape parameters. The effects of side length, L, beam thickness, t, and height, h, on E* were investigated individually. FEA results revealed that there is a relationship between E* and the relative density and shape parameters. Among them, t has the most significant effect on E*. Numerical results were also compared with the results from modified general function for cellular structures and modified formula for triangular honeycomb. The E* predicted by the proposed analytical solution shows the best agreement with the numerical results. Finally, tensile tests were carried out using AlSi10 Mg triangular lattice structures manufactured by selective laser melting (SLM) process. The experimental results show that both analytical and numerical solutions are able to predict E* with good accuracy. In the future, the proposed solution can be used to design lightweight structures with triangular unit cells.
Investigation on the Effect of Surface Wettability on a Two-Phase Flow in a Compressor Cascade
Authors: Neupert Niklas , Harbeck Janneck Christoph , Joos Franz
Published: July 2018

In recent years overspray fogging has become a powerful means for power augmentation of industrial gas turbines. Despite the positive thermodynamic effect on the cycle droplets entering the compressor increase the risk of water droplet erosion. Further deposited water leads to a higher sensitivity toward fouling due to an increased stickiness of the blades. Therefore, erosion resistant hydrophobic coatings are applied to the first stages of compressors. Although some patents claim the use of such coatings the aerodynamic impact of a different wettability is not regarded so far. This issue was addressed in the field of aerodynamic efficiency of wings in heavy rain showing higher penalty for hydrophobic coatings. In this study, the issue of a different blade surface wettability in a linear transonic compressor cascade is addressed. Different coatings are applied resulting in contact angles of 51–95 deg. The inflow Mach number was fixed at design inflow Mach number, and the inflow angle was varied over a broad range. The effect on the water film pattern is analyzed in terms of position of film breakup, rivulet width, and totally wetted surface. The performance of the cascade under two-phase flow was analyzed using laser Doppler anemometry/phase Doppler anemometry measurement technique in terms of loss coefficient based on wake momentum thickness and flow turning. It is shown that the wettability of the surface has significant effects on the film structure leading to a lower fraction of wetted surface with increasing contact angle. The influence on performance is limited to effects in the proximity of the surface and is dependent on operation point. While in design conditions hydrophilic coating show lower losses, the trend is vice-versa for off-design conditions. The data represent first experimental work on the influence of surface wettability in a droplet-laden flow supporting positive features for hydrophobic coatings in gas turbine compressors.
Optimization of an Endoscopic Radiofrequency Ablation Electrode
Authors: Hanks Bradley , Frecker Mary , Moyer Matthew
Published: July 2018

Radiofrequency ablation (RFA) is an increasingly used, minimally invasive, cancer treatment modality for patients who are unwilling or unable to undergo a major resective surgery. There is a need for RFA electrodes that generate thermal ablation zones that closely match the geometry of typical tumors, especially for endoscopic ultrasound-guided (EUS) RFA. In this paper, the procedure for optimization of an RFA electrode is presented. First, a novel compliant electrode design is proposed. Next, a thermal ablation model is developed to predict the ablation zone produced by an RFA electrode in biological tissue. Then, a multi-objective genetic algorithm is used to optimize two cases of the electrode geometry to match the region of destructed tissue to a spherical tumor of a specified diameter. This optimization procedure is then applied to EUS-RFA ablation of pancreatic tissue. For a target 2.5 cm spherical tumor, the optimal design parameters of the compliant electrode design are found for two cases. Cases 1 and 2 optimal solutions filled 70.9% and 87.0% of the target volume as compared to only 25.1% for a standard straight electrode. The results of the optimization demonstrate how computational models combined with optimization can be used for systematic design of ablation electrodes. The optimization procedure may be applied to RFA of various tissue types for systematic design of electrodes for a specific target shape.
Novel Design and Validation of a Micro Instrument in an Ear Grommet Insertion Device
Authors: Ng Cailin , Liang Wenyu , Gan Chee Wee , Lim Hsueh Yee , Tan Kok Kiong
Published: July 2018

An automated surgical device, the ventilator tube applicator (VTA), enables a grommet insertion surgery for patients with otitis media with effusion (OME) to be completed in a short time automatically and precisely, eliminating the use of general anesthesia (GA) typically required in such procedure. However, its current design limits the usefulness of the device as it is restricted by the properties of the tympanic membrane (TM), such as angle, thickness, and strength. Therefore, a novel design was conceptualized and the insertion control algorithm was improved to overcome the current challenges of the VTA. This innovative cover-cutter instrument design allows three-dimensional (3D) motion on an oblique surface using a single axis actuator. Experimental results on mock membranes showed great improvements in terms of robustness and success rate. The new design allowed the procedure to be performed on wider range of TM angles and hence increased the effectiveness of VTA. Grommet insertion force was reduced by an average of 66%, and the overall peak force reduced by an average of 14%. Finite element (FE) analysis on a cadaveric TM model further validated the usefulness of the cover-cutter instrument, and showed some interesting insights in the grommet insertion process.
Creating a Small Anchor to Eliminate Large Knots in Mesh and Tape Suture
Authors: Green Jason L. , Glisson Richard , Hung Jane , Ibrahim Mohamed , Farjat Alfredo , Liu Beiyu , Gall Ken , Levinson Howard
Published: July 2018

Wide mesh or tape sutures are used to close high-tension wounds such as in hernia or tendon repair. However, wide sutures produce large knots that are susceptible to increased palpability, infection, and foreign body response. To prevent such adverse events, we developed a small suture anchor to replace wide suture knots. The suture anchor was iteratively developed using three-dimensional (3D) design software and produced via 3D printing. Anchor prototypes underwent monotonic, cyclic fatigue, and stress-life testing in a benchtop soft tissue suture model. Results were compared to a standard of care knot and alternative suture fixation devices. The final anchor design was selected based on minimal size and mechanical performance. The size of the final anchor (200 mm3) was 33% smaller than a tape suture knot and 68% smaller than a mesh suture knot. Monotonic testing of mesh and tape sutures revealed a significantly greater anchor failure load compared to knot and alternative fixations (p < 0.05). Additionally, all anchors successfully completed cyclic fatigue testing without failure while other fixations, including knot, failed to complete cyclic fatigue testing multiple times. Stress-life testing demonstrated durable anchor fixation under varying tensile stresses. Failure mode analysis revealed anchor fracture and tissue failure as modes of anchor failure, each of which occurred at supraphysiologic forces. We created a small suture anchor that significantly outperforms knot and alternative suture fixations in benchtop testing and addresses concerns of increased palpability, infection, and foreign body response from large suture knots.
Engineering Evaluation of the Performance of an Automatic Peripheral Oxygen Controller Using a Neonatal Respiratory Model
Authors: Faqeeh Akram , Fales Roger , Pardalos John , Amjad Ramak , Zaniletti Isabella , Hou Xuefeng
Published: July 2018

Premature infants often require respiratory support with a varying concentration of the fraction of inspired oxygen FiO2 to keep the arterial oxygen saturation typically measured using a peripheral sensor (SpO2) within the desired range to avoid both hypoxia and hyperoxia. The widespread practice for controlling the fraction of inspired oxygen is by manual adjustment. Automatic control of the oxygen to assist care providers is desired. A novel closed-loop respiratory support device with dynamic adaptability is evaluated nonclinically by using a neonatal respiratory response model. The device demonstrated the ability to improve oxygen saturation control over manual control by increasing the proportion of time where SpO2 is within the desired range while minimizing the episodes and periods where SpO2 of the neonatal respiratory model is out of the target range.
Study of Buoyancy-Driven Flow Effect on Salt Gradient Solar Ponds Performance
Authors: Derakhshan Shahram , Mirazimzadeh Seyedeh Elnaz , Pazireh Syamak
Published: July 2018

Salt gradient solar ponds are the ponds in which due to existence of saline and salt gradient layers, lower layers are denser and avoid the natural convection phenomenon to occur so that solar radiation energy can be stored in the lowest zone. In this study, one-dimensional (1D) and two-dimensional (2D) numerical approaches have been implemented to simulate unsteady buoyancy-driven flow of solar ponds. In 1D method, the pond has been investigated in terms of the layers thicknesses so that the variation of temperature is calculated by energy conservation equation. The formulized radiation term was used as energy source term in energy equation. The results of 1D approach were validated with an experimental study and then optimization was carried out to determine the maximum thermal efficiency for an interval of layers height. Since the stability of the solar pond cannot be determined by 1D simulation, a 2D approach was considered to show the stability for different nonconvective zone (NCZ) heights and different salt gradients. In 2D study, in order to investigate hydrodynamic and thermal behavior of saltwater fluid, a numerical approach was used to simulate temperature gradients throughout the pond. The results of 2D numerical method are validated with an experimental data. The effect of linear and nonlinear salt gradient was considered.
An NOx Sensor-Based Direct Algebraic Approach-Newton Observer for Urea Selective Catalytic Reduction System State Estimations
Authors: Lin Qinghua , Chen Pingen
Published: July 2018

NOx sensor-based state estimations for urea-based selective catalytic reduction (SCR) systems have attracted much attention in the past several years because of their significant importance in achieving high NOx conversion efficiency and low ammonia slip at low operation cost. Most of the existing SCR state estimation techniques require sophisticated design processes and significant tuning efforts, which may prevent them from widespread applications to production urea-SCR systems. In addition, the existing SCR state observers may not be able to achieve fast and accurate estimations due to the corresponding slow estimation error dynamics. The purpose of this study was to design a straightforward and effective NOx sensor-based SCR state estimation algorithm for decoupling post-SCR NOx sensor signals (NOx concentration, ammonia concentration), and for estimating ammonia coverage ratio of the urea-SCR systems. A singular-perturbation-based approach was applied to attain the reduced-order SCR model by decoupling the fast NO and NH3 concentration dynamic models from the slow ammonia coverage ratio dynamics model. Based on the reduced-order model, a direct algebraic approach (DAA)-Newton observer was proposed for estimating ammonia coverage ratio. The achieved ammonia coverage ratio estimation was applied to estimate the post-SCR NOx and NH3 concentrations. Simulation verification results under US06 cycle proved the effectiveness of the proposed method in accurately estimating the aforementioned key SCR states. The proposed observer can potentially be popularly applied to the production SCR systems for the advanced SCR control systems and on-board diagnostics.
Optimal Design of Double-Mass Dynamic Vibration Absorbers Minimizing the Mobility Transfer Function
Authors: Asami Toshihiko , Mizukawa Yoshito , Ise Tomohiko
Published: July 2018

Although the vibration suppression effects of precisely adjusted dynamic vibration absorbers (DVAs) are well known, multimass DVAs have recently been studied with the aim of further improving their performance and avoiding performance deterioration due to changes in their system parameters. One of the present authors has previously reported a solution that provides the optimal tuning and damping conditions of the double-mass DVA and has demonstrated that it achieves better performance than the conventional single-mass DVA. The evaluation index of the performance used in that study was the minimization of the compliance transfer function. This evaluation function has the objective of minimizing the absolute displacement response of the primary system. However, it is important to suppress the absolute velocity response of the primary system to reduce the noise generated by the machine or structure. Therefore, in the present study, the optimal solutions for DVAs were obtained by minimizing the mobility transfer function rather than the compliance transfer function. As in previous investigations, three optimization criteria were tested: the H∞ optimization, H2 optimization, and stability maximization criteria. In this study, an exact algebraic solution to the H∞ optimization of the series-type double-mass DVA was successfully derived. In addition, it was demonstrated that the optimal solution obtained by minimizing the mobility transfer function differs significantly at some points from that minimizing the compliance transfer function published in the previous report.
Statistical Characterization of Human Brain Deformation During Mild Angular Acceleration Measured In Vivo by Tagged Magnetic Resonance Imaging
Authors: Chan Deva D. , Knutsen Andrew K. , Lu Yuan-Chiao , Yang Sarah H. , Magrath Elizabeth , Wang Wen-Tung , Bayly Philip V. , Butman John A. , Pham Dzung L.
Published: July 2018

Understanding of in vivo brain biomechanical behavior is critical in the study of traumatic brain injury (TBI) mechanisms and prevention. Using tagged magnetic resonance imaging, we measured spatiotemporal brain deformations in 34 healthy human volunteers under mild angular accelerations of the head. Two-dimensional (2D) Lagrangian strains were examined throughout the brain in each subject. Strain metrics peaked shortly after contact with a padded stop, corresponding to the inertial response of the brain after head deceleration. Maximum shear strain of at least 3% was experienced at peak deformation by an area fraction (median±standard error) of 23.5±1.8% of cortical gray matter, 15.9±1.4% of white matter, and 4.0±1.5% of deep gray matter. Cortical gray matter strains were greater in the temporal cortex on the side of the initial contact with the padded stop and also in the contralateral temporal, frontal, and parietal cortex. These tissue-level deformations from a population of healthy volunteers provide the first in vivo measurements of full-volume brain deformation in response to known kinematics. Although strains differed in different tissue type and cortical lobes, no significant differences between male and female head accelerations or strain metrics were found. These cumulative results highlight important kinematic features of the brain's mechanical response and can be used to facilitate the evaluation of computational simulations of TBI.
Load Mitigation Using Slotted Flaps in Offshore Wind Turbines
Authors: Thakur Shilpa , Abhinav K. A. , Saha Nilanjan
Published: July 2018

This paper focuses on load mitigation by implementing controllable trailing-edge slotted flaps on the blades of an offshore wind turbine (OWT). The benchmark NREL 5 MW horizontal axis OWT is subjected to coupled stochastic aerodynamic-hydrodynamic analysis for obtaining the responses. The OWT is supported on three different fixed-bottom structures situated in various water depths. Blade element momentum (BEM) theory and Morison's equation are used to compute the aerodynamic and hydrodynamic loads, respectively. Presently, the load reduction obtained by means of the slotted flaps is regulated using an external dynamic link library considering the proportional-integral-derivative (PID) controller. BEM theory is presently modified to account for unsteady effects of flaps along the blade span. The present analysis results show reduction up to 20% in blade and tower loads for the turbine with different support structures on implementing controllable trailing edge flaps (TEFs). This study can form the basis for evaluating the performance of large-scale fixed OWT rotors.
Risk-Based Approach to Evaluate Casing Integrity in Upstream Wells
Authors: Al-Ajmi Mohammed D. , Al-Shehri Dhafer , Mahmoud Mohamed , Al-Hajri Nasser M.
Published: July 2018

Downhole casing leaks in oil and gas wells will highly impact the shallow water horizons and this will affect the environment and fresh water resources. Proactive measures and forecasting of this leak will help eliminate the consequences of downhole casing leaks and, in turn, will protect the environment. Additionally, downhole casing leaks may also cause seepage of toxic gases to the fresh water zones and to the surface through the casing annuli. In this paper, we introduced a risk-based methodology to predict the downhole casing leaks in oil and gas wells using advanced casing corrosion logs such as electromagnetic logs. Downhole casing corrosion was observed to assess the remaining well life. Electromagnetic (EM) corrosion logs are the current practice for monitoring the casing corrosion. The corrosion assessment from EM logs is insufficient because these logs cannot read in multiple casings in the well. EM tool gives average reading for the corrosion in the casing at a specific depth and it does not indicate the orientation of the corrosion. EM log does not assess the 360 deg corrosion profile in the casing and it only provides average value and this may lead to wrong decision. All of this makes EM logs uncertain tools to assess the corrosion in the downhole casing. A unified criterion to assess the corrosion in the casing and to decide workover operations or not has been identified to minimize the field challenges related to this issue. A new approach was introduced in this paper to enhance the EM logs to detect the downhole casing corrosion. Corrosion data were collected from different fields (around 500 data points) to build a probabilistic approach to assess the casing failure based on the average metal loss from the EM corrosion log. The failure model was used to set the ranges for the casing failure and the probability of casing failure for different casings. The prediction of probability of failure (PF) will act as proactive maintenance which will help prevent further or future casing leaks.
Design Optimization Study of a Nonlinear Energy Absorber for Internal Combustion Engine Pistons
Authors: Dolatabadi N. , Theodossiades S. , Rothberg S. J.
Published: July 2018

Piston impacts against the cylinder liner are the most significant sources of mechanical noise in internal combustion (IC) engines. Traditionally, the severity of impacts is reduced through the modification of physical and geometrical characteristics of components in the piston assembly. These methods effectively reduce power losses at certain engine operating conditions. Frictional losses and piston impact noise are inversely proportional. Hence, the reduction in power loss leads to louder piston impact noise. An alternative method that is robust to fluctuations in the engine operating conditions is anticipated to improve the engine's noise, vibration and harshness (NVH) performance, while exacerbation in power loss remains within the limits of conventional methods. The concept of targeted energy transfer (TET) through the use of nonlinear energy sink (NES) is relatively new and its application in automotive powertrains has not been demonstrated yet. In this paper, a TET device is conceptually designed and optimized through a series of parametric studies. The dynamic response and power loss of a piston model equipped with this nonlinear energy sink is investigated. Numerical studies have shown a potential in reducing the severity of impact dynamics by controlling the piston's secondary motion.
Design of Semirigid Wearable Devices Based on Skin Strain Analysis
Authors: Barrios-Muriel J. , Romero Sánchez F. , Alonso F. J. , Salgado D. R.
Published: July 2018

Nowadays, both usability and comfort play a key role in the development of medical and wearable products. When designing any device that is in contact with the human body, the mechanical behavior of the embraced soft tissue must be known. The unavoidable displacement of the soft tissue during motion may lead to discomfort and, thus, the removal of the wearable product. This paper presents a new methodology to design and test a wearable device based on the measurement of the dynamic skin strain field. Furthermore, from this field, the anatomical lines with minimum strain (lines of nonextension (LoNEs)) are calculated to design the structural parts of the wearable device. With this new criterion, the resulting product is not only optimized to reduce the friction in skin-device interface, but fully personalized to the patient's morphology and motion. The methodology is applied to the design of an ankle-foot wearable orthosis for subjects with ankle dorsiflexors muscles weakness due to nervous system disorders. The results confirm that the use of LoNEs may benefit the design of products with a high interaction with the skin.
Energy Consumption and Drying Time Optimization of Convective Drying for Performance Improvement: Response Surface Methodology and Lattice Boltzmann Method
Authors: Majdi H. , Esfahani J. A.
Published: July 2018

In this paper, an optimization procedure is presented by response surface method to optimize the temperature and velocity of drying air and thickness of the moist object inside the dryer. The optimization procedure is performed to determine the minimum drying time and energy consumption as responses. A two-dimensional (2D) numerical solution is accomplished to analyze coupled heat and mass transfer occurring during drying of an apple slice. The air flow and the moist object are solved conjugate, while the heat and mass transfer equations are solved coupled together using lattice Boltzmann method (LBM). Beside this, a sensitivity analysis is executed to calculate the sensitivity of the responses (drying time and energy consumption) to the control factors. Results reveal that the real optimized parameters for the minimum drying time and energy consumption are temperature (T = 80 °C), velocity (V = 0.10404 m/s), and thickness ratio (TR = 0.1). The results of numerical solution are compared to the experimental results, presenting a reasonable agreement. This analysis could be useful in food drying.
Mathematical Modeling of a Long Finned Tube Heating and Cooling in a Multizone Furnace
Authors: Liang Chao , Patel Darshil R. , Shelat Maulik R.
Published: July 2018

To support an effort to setup an industrial scale production facility to produce metal substrates coated with porous boiling surface (PBS) coating to enhance boiling heat transfer performance of these metal substrates, an axisymmetric transient heat transfer model with boundary conditions varying both in time and length dimensions has been proposed and solved to obtain the temperature evolution along the inner surface of a long finned tube heating and cooling in a multizone furnace. Experiments for finned tube heating and cooling were conducted using a single-zone batch furnace, and the experimental data obtained were compared with the simulation results to establish reasonable confidence in the proposed model and boundary conditions. A parametric study on several important operating parameters was conducted to gain better insights that can be used in making design and operating decisions. If required, the model can conveniently be extended to other types of substrates and furnace dimensions.
On Averaging and Vibrational Control of Mechanical Systems With Multifrequency Inputs
Authors: Tahmasian Sevak
Published: July 2018

This paper discusses the averaging, control authority, and vibrational control of mechanical control-affine systems with high-frequency, high-amplitude inputs. The inputs have different frequencies of the same order. This work is an extension of the existing averaging method for high-frequency mechanical systems with single-frequency inputs. Vibrational control authority of mechanical control-affine systems is introduced, and the effects of inputs' waveform and frequency on vibrational control authority are investigated. The results show that, in general, using multifrequency inputs may result in lower control authority of mechanical systems compared to single-frequency inputs, especially when using harmonic inputs. The results on vibrational control authority of the systems with multifrequency inputs are demonstrated using vibrational control of a horizontal pendulum with two inputs. This paper also discusses the averaging of multiple-time-scale control systems.
Exploring Natural Strategies for Bio-Inspired Fault Adaptive Systems Design
Authors: Arroyo Marvin , Huisman Nicholas , Jensen David C.
Published: July 2018

Fault adaptive design seeks to find the principles and properties that enable robustness, reliability, and resilience to implement those features into engineering products. In nature, this characteristic of adaptability is the fundamental trait that enables survival. Utilizing adaption strategy is a new area of research exploration for bio-inspired design (BID). In this paper, we introduce a tool for BID for fault adaption. Further, we discuss insights from using this tool in an undergraduate design experiment. The goal of the tool is to assist designers to develop fault adaptive behaviors in engineering systems using nature as inspiration. This tool is organized as a binary tree where branches that represent the specific details of how an organism achieves an adaptive behavior or characteristic. Results from an initial study indicate, for the specific challenge of designing fault adaption into a system, a strategy-based method can provide designers with innovative analogies and help provide the details needed to bridge the gap between analogy and engineering implementation.
Double Pulse Low-Frequency Modulation for High-Power Double-Wire Pulsed GMAW
Authors: Wu Kaiyuan , Liang Zhuoyong , Yin Tong , He Zuwei , Zeng Min
Published: July 2018

A double pulse low-frequency modulation method was proposed to improve heat input control and enhance weld quality during high-power double-wire pulsed gas metal arc welding (GMAW). By constructing a mathematical model, relationships between parameters of double pulse low-frequency modulation and energy input were analyzed. A correction coefficient was added to overcome physical characteristics of charging and discharging in a welding circuit. Thus, qualitative relationships between parameters of double pulse low-frequency modulation and energy input were described more accurately. Bead-on-plate welding experiments were conducted in a synchronous phase mode. A stable welding process was achieved and perfect weld bead shapes were acquired. Modulation frequency imposed a significant effect on both weld width and penetration, while modulation duty cycle had a significant effect on penetration and little effect on weld width. Modulation frequency significantly influenced refinement of grain size. Weak and strong pulses of low-frequency modulation improved heat input control, strengthened stirring action of double pulse on weld pool, and enhanced fluidity of molten metals, thereby contributing to optimization of weld quality.
Heat Transfer Modulation by Inertial Particles in Particle-Laden Turbulent Channel Flow
Authors: Liu Caixi , Tang Shuai , Dong Yuhong , Shen Lian
Published: July 2018

We study the effects of particle-turbulence interactions on heat transfer in a particle-laden turbulent channel flow using an Eulerian–Lagrangian simulation approach, with direct numerical simulation (DNS) for turbulence and Lagrangian tracking for particles. A two-way coupling model is employed in which the momentum and energy exchange between the discrete particles and the continuous fluid phase is fully taken into account. Our study focuses on the modulations of the temperature field and heat transfer process by inertial particles with different particle momentum Stokes numbers (St), which in a combination of the particle-to-fluid specific heat ratio and the Prandtl number results in different particle heat Stokes numbers. It is found that as St increases, while the turbulent heat flux decreases due to the suppression of wall-normal turbulence velocity fluctuation, the particle feedback heat flux increases significantly and results in an increase in the total heat flux. The particle thermal feedback effect is illustrated using the instantaneous structures and statistics of the flow and temperature fields. The mechanisms of heat transfer modulation by inertial particles are investigated in detail. The budget of turbulent heat flux is examined. Moreover, by taking advantage of the ability of numerical simulation to address different momentum and heat processes separately, we investigate in detail the two processes of particles affecting heat transfer for the first time, namely the direct effect of particle thermal feedback to the fluid (i.e., heat feedback) and the indirect effect of the modulation of turbulent velocity field induced by the particles (i.e., momentum feedback). It is found that the contribution of heat transfer from turbulent convection is reduced by both heat and momentum feedback due to the decrease of the turbulent heat flux. The contribution of heat transfer from particle transport effects is barely influenced by the momentum feedback, even if St is large and is mainly affected by the heat feedback. Our results indicate that both heat and momentum feedback are important when the particle inertia is large, suggesting that both feedback processes need to be taken into account in computation and modeling.
Nuclear Radiation Monitoring Using Plants
Authors: Islam Mohammad , Janssen Douglas , Romero-Talamas Carlos , Kostov Dan , Wang Wanpeng , Liu Zhongchi , Singh Narsingh B. , Choa Fow-Sen
Published: July 2018

Plants exhibit complex responses to change in environmental conditions such as radiant heat flux, water quality, airborne pollutants, and soil contents. We seek to utilize natural chemical and electrophysiological response of plants to develop novel plant-based sensor networks. Our present work focuses on plant responses to nuclear radiation—with the goal of monitoring plant responses as benchmarks for detection and dosimetry. In our study, we used plants including Cactus, Arabidopsis, Dwarf mango (pine), Euymus, and Azela. We demonstrated that these plants Chlorophyll-a (F680) to Chlorophyll-b (F735) ratio can be changed according to the radiation dose amount. The recovery processes and speed are different for different plants.
Functional Information of System Components Influenced by Counteractions on Computer-Based Procedure
Authors: Suryono Tulis Jojok , Gofuku Akio
Published: July 2018

In an emergency condition of nuclear power plant, operators have to mitigate the accident in order to remove the decay heat and to prevent the release of radioactive material to the environment following the emergency operating procedures (EOPs). The action of operators on a component, for example, changing the parameter level of a component, which is described in a procedure step, will impact other components of the plant and the plant behavior. Nowadays, the advanced main control rooms have been equipped with the computer-based procedures (CBPs) which provide some features and benefits which are not available in paper-based procedures. However, most of CBPs do not provide information of the impact of the counteractions on each procedure step (components influenced and future plant behavior) although it is useful for operators to understand the purpose of the procedure steps before making decisions and taking the actions. This paper discusses the functional information and the method to generate the information using multilevel flow modeling (MFM) model of operator actions on some procedure steps of a simplified EOP of pressurized water reactor (PWR) plant, as an example.
Design Verification for Control Logic in Nuclear Power Plant
Authors: Li Hui , Zhang Guangxin
Published: July 2018

The control function for process, heating, ventilation, and air conditioning, and electrical systems in nuclear power plant (NPP) are represented by control logic diagram. To develop distributed control system (DCS), the designer and supplier should complete the activities of control logic configuration, testing, and verification, which are based on control logic diagram. Design verification is an effective method to ensure the correctness of control logic design. This paper represents a system, which is capable of implementing control logic design verification automatically for NPP instrumentation and control (I&C) system, as well as an overview of the procedure and some examples by using this system. With the design data (including control requirements and control logic diagrams in computer-readable format) and simulation technology, this system automatically performs design verification based on different rules and confirms the design outputs meet the inputs—the control requirements of plant's systems. Finally, a conclusion about the design verification system and future scenarios is given.
Investigation on the Effects of Freeze-Thaw Action on the Pore Water Pressure Variations of Soils
Authors: Zhang Lianhai , Ma Wei , Yang Chengsong
Published: July 2018

Freeze-thaw action changes soil microstructure and thus has a great influence on physical and mechanical properties of soils, which is closely correlated to pore water pressure (PWP). Herein, the PWPs of sandy soil and silty clay were measured in laboratory during freeze-thaw cycles (FTC). Experimental results showed that PWP was influenced by temperature, freeze-thaw history (i.e., number of freeze-thaw cycle), soil type and others. The PWP experienced a periodical change as temperatures periodically changes during the FTC testing, the PWP decreased during freezing and increased during thawing. Soil type has a slight influence on the variation of PWP, both in character and extent. A theoretical analysis of PWP in frozen soil was given to explain the PWP changes. In addition, the PWP depression during freezing was a major driving force for water migration. The PWP variations are highly relevant to the changes in soil microstructure such as soil particle (grain size composition and mineral composition), pore structure, and particle arrangement, which will be the focus of further research.
Radiative Heat and Mass Transfer Analysis of Micropolar Nanofluid Flow of Casson Fluid Between Two Rotating Parallel Plates With Effects of Hall Current
Authors: Shah Zahir , Islam Saeed , Ayaz Hamza , Khan Saima
Published: July 2018

The present research aims to examine the micropolar nanofluid flow of Casson fluid between two parallel plates in a rotating system with effects of thermal radiation. The influence of Hall current on the micropolar nanofluids have been taken into account. The fundamental leading equations are transformed to a system of nonlinear differential equations using appropriate similarity variables. An optimal and numerical tactic is used to get the solution of the problem. The convergence and comparison have been shown numerically. The impact of the Hall current, Brownian movement, and thermophoresis phenomena of Casson nanofluid have been mostly concentrated in this investigation. It is found that amassed Hall impact decreases the operative conductivity which intends to increase the velocity field. The temperature field enhances with larger values of Brownian motion thermophoresis effect. The impacts of the Skin friction coefficient, heat flux, and mass flux have been deliberate. The skin friction coefficient is observed to be larger for k=0, as compared to the case of k=0.5. Furthermore, for conception and visual demonstration, the embedded parameters have been deliberated graphically.
Transmutation Study of Minor Actinides in Mixed Oxide Fueled Typical Pressurized Water Reactor Assembly
Authors: Chen Shengli , Yuan Cenxi
Published: July 2018

The management of long-lived radionuclides in spent fuel is a key issue to achieve the closed nuclear fuel cycle and the sustainable development of nuclear energy. The partitioning-transmutation method is supposed to efficiently treat the long-lived radionuclides. Accordingly, the transmutation of long-lived minor actinides (MAs) is significant for the postprocessing of spent fuel. In the present work, the transmutations in pressurized water reactor (PWR) mixed oxide (MOX) fuel are investigated through the Monte Carlo neutron transport method. Two types of MAs are homogeneously incorporated into MOX fuel assembly with different mixing ratios. In addition, two types of design of semihomogeneous loading of 237Np in MOX fuels are studied. The results indicate an overall nice efficiency of transmutation in PWR with MOX fuel, especially for 237Np and 241Am, which are primarily generated in the current uranium oxide fuel. In addition, the transmutation efficiency of 237Np is excellent, while its inclusion has no much influence on other MAs. The flattening of power and burnup are achieved by semihomogeneous loading of MAs. The uncertainties of Monte Carlo method are negligible, while those due to nuclear data change little the conclusions of the transmutation of MAs. The transmutation of MAs in MOX fuel is expected to be an efficient method for spent fuel management.
Poly(Propylene Fumarate)–Hydroxyapatite Nanocomposite Can Be a Suitable Candidate for Cervical Cages
Authors: Teng Yong , Giambini Hugo , Rezaei Asghar , Liu Xifeng , Lee Miller A. , Waletzki Brian E. , Lu Lichun
Published: July 2018

A wide range of materials have been used for the development of intervertebral cages. Poly(propylene fumarate) (PPF) has been shown to be an excellent biomaterial with characteristics similar to trabecular bone. Hydroxyapatite (HA) has been shown to enhance biocompatibility and mechanical properties of PPF. The purpose of this study was to characterize the effect of PPF augmented with HA (PPF:HA) and evaluate the feasibility of this material for the development of cervical cages. PPF was synthesized and combined with HA at PPF:HA wt:wt ratios of 100:0, 80:20, 70:30, and 60:40. Molds were fabricated for testing PPF:HA bulk materials in compression, bending, tension, and hardness according to ASTM standards, and also for cage preparation. The cages were fabricated with and without holes and with porosity created by salt leaching. The samples as well as the cages were mechanically tested using a materials testing frame. All elastic moduli as well as the hardness increased significantly by adding HA to PPF (p < 0.0001). The 20 wt % HA increased the moduli significantly compared to pure PPF (p < 0.0001). Compressive stiffness of all cages also increased with the addition of HA. HA increased the failure load of the porous cages significantly (p = 0.0018) compared with nonporous cages. PPF:HA wt:wt ratio of 80:20 proved to be significantly stiffer and stronger than pure PPF. The current results suggest that this polymeric composite can be a suitable candidate material for intervertebral body cages.
Dielectric Elastomer Fluid Pump of High Pressure and Large Volume Via Synergistic Snap-Through
Authors: Wang Yingxi , Li Zhe , Qin Lei , Caddy George , Yap Choon Hwai , Zhu Jian
Published: July 2018

Harnessing reversible snap-through of a dielectric elastomer (DE), which is a mechanism for large deformation provided by an electromechanical instability, for large-volume pumping has proven to be feasible. However, the output volume of snap-through pumping is drastically reduced by adverse pressure gradient, and large-volume pumping under high adverse pressure gradient by a DE pump has not been realized. In this paper, we propose a new mechanism of DE fluid pumping that can address this shortcoming by connecting DE pumps of different membrane stiffnesses serially in a pumping circuit and by harnessing synergistic interactions between neighboring pump units. We build a simple serial DE pump to verify the concept, which consists of two DE membranes. By adjusting the membrane stiffness appropriately, a synergistic effect is observed, where the snap-through of membrane 1 triggers the snap-through of membrane 2, ensuring that a large volume (over 70 ml/cycle) can be achieved over a wide range of large adverse pressure gradients. In comparison, the conventional single DE pump's pumping volume rapidly decreased beyond a low adverse pressure gradient of 0.196 kPa. At the pressure difference of 0.98 kPa, the serial DE pump's pumping volume is 4185.1% larger than that of the conventional DE pump. This pumping mechanism is customizable for various pressure ranges and enables a new approach to design DE-based soft pumping devices such as a DE total artificial heart, which requires large-volume pumping over a wide range of pressure difference.
Microhole Drilling by Double Laser Pulses With Different Pulse Energies
Authors: Liu Ze , Wu Benxin , Xu Rong , Zhao Kejie , Shin Yung C.
Published: July 2018

Previous investigations on “double-pulse” nanosecond (ns) laser drilling reported in the literature typically utilize double pulses of equal or similar pulse energies. In this paper, “double-pulse” ns laser drilling using double pulses with energies differing by more than ten times has been studied, where both postprocess workpiece characterizations and in situ time-resolved shadowgraph imaging observations have been performed. A very interesting physical phenomenon has been discovered under the studied conditions: the “double-pulse” ns laser ablation process, where the low-energy pulse precedes the high-energy pulse (called “low-high double-pulse” laser ablation) by a suitable amount of time, can produce significantly higher ablation rates than “high-low double-pulse” or “single-pulse” laser ablation under a similar laser energy input. In particular, “low-high double-pulse” laser ablation at a suitable interpulse separation time can drill through a ∼0.93 mm thick aluminum 7075 workpiece in less than 200 pulse pairs, while “high-low double-pulse” or “single-pulse” laser ablation cannot drill through the workpiece even using 1000 pulse pairs or pulses, respectively. This indicates that “low-high double-pulse” laser ablation has led to a significantly enhanced average ablation rate that is more than five times those for “single-pulse” or “high-low double-pulse” laser ablation. The fundamental physical mechanism for the ablation rate enhancement has been discussed, and a hypothesized explanation has been given.
Ball and Beam Balancing Mechanism Actuated With Pneumatic Artificial Muscles
Authors: Šitum Željko , Trslić Petar
Published: July 2018

The paper presents the results of modeling and control of an original and unique ball-on-beam system with a pneumatic artificial muscle pair in an antagonistic configuration. This system represents a class of under-actuated, high-order nonlinear systems, which are characterized by an open-loop unstable equilibrium point. Since pneumatic muscles have elastic, nonlinear characteristics, they are more difficult to control. Considering that an additional nonlinearity is added to the system which makes it harder to stabilize. The nonlinear mathematical model has been derived based on the physical model of the ball-on-beam mechanism, the beam rotating by using an antagonistic muscle pair and the pneumatic muscle actuated by a proportional valve. Based on the nonlinear model, the linearized equations of motion have been derived and a control-oriented model has been developed, which is used in the state feedback controller design procedure. The proposed state feedback controller has been verified by means of computer simulations and experimentally on the laboratory setup. The simulation and experimental results have shown that the state feedback controller can stabilize the ball-on-beam system around an equilibrium position in the presence of external disturbances and to track a reference trajectory with a small tracking error.
The Role of Impulse, Tissue Stretching, and Tip Geometry for Tissue Penetration of Polymer Needles
Authors: Silva Patricia , Drakidis Alexandros , Gomes Silvana , Lenau Torben A.
Published: July 2018

Polymer needles for medical injections offer a range of opportunities like compatibility with magnetic resonance scanning and simultaneous delivery of more than one drug. However, the lower stiffness property of polymers compared to steel is a challenge for penetration. This paper explores strategies for higher penetration success, which include impulse insertion, tissue stretching, and different tip geometries. The strategies are experimentally examined using three layers of nitrile rubber gloves and sticking glue to create an artificial skin model. It is demonstrated that polymer needles have higher penetration rates when the strategies are applied. Penetration rates were only 10–20% when using slow speed insertion (0.2 mm/s) but 100% penetration rates was achieved using impulse insertion. Penetration forces are similar for slow insertion speed and high speed (impulse insertion) and for needles made out of different material (polymer or steel). Conical and pyramidal tips were studied for polymer needles and a commercial bevel steel needle tip. The result was lower penetration forces and 100% penetration success was possible using the pyramidal polymer needles. For the model in study was observed a similar behavior (penetration force and rate of penetration success) for steel and polymer pyramidal needles. An analysis of variance statistical analysis show significance when using springs and strain, as well for the combination of both.