bluuebunny/crossref_metadata_2025 huggingface dataset:
Muscle tenderness score in temporomandibular disorders patients: A case‐control study
Authors: Almoznino Galit , Zini Avraham , Zakuto Avraham , Zlutzky Hulio , Bekker Stav , Shay Boaz , Haviv Yaron , Sharav Yair , Benoliel Rafael
Published: November 2018

Background

The total tenderness score (TTS) is commonly used in headache practice and contributes valuable information.

Objective

To assess muscle tenderness scores in patients diagnosed with Temporomandibular disorders (TMD) and analyse their associations with various demographic and clinical parameters.

Methods

Masticatory (MTS), cervical (CTS) and TTSs were analysed in this case‐control study among 192 TMD patients and 99 controls. The study included a questionnaire and a clinical examination following RDC/TMD guidelines. Data were analysed using: Pearson's chi‐square, analysis of variance, t test and Bonferroni post hoc. To examine the factors associated with MTS score in a multivariate manner, a conceptual hierarchical multiple regression model was adopted.

Results

Masticatory and TTS differed between TMD sub‐groups and controls. Muscle tenderness was positively associated with: female sex, whiplash history, parafunction, co‐morbid pains such as headaches and body pain, pain intensity, onset, frequency and duration. In the conceptual hierarchical multiple regression model, pain onset, frequency and duration, co‐morbid pains were mediators in the relationship between TMD diagnosis and MTS.

Conclusion

Muscle tenderness scores were positively associated with TMD disease characteristics and co‐morbid pain conditions, which may reflect associations with disease severity. MTS differed between TMD populations and may be used in routine patient workup, to assess MMD severity and changes over time as well as treatments response and as a research tool. MTS can be used as a common methodology to describe both headaches and masticatory muscle disorders and to facilitate interprofessional research and crosstalk between a headache and oro‐facial pain practitioners.
How mandatory is the mandatory reporting of children at risk?
Authors: Isaacs David , Britton Philip N , Kilham Henry A , Bag Shopna , Marks Susan
Published: November 2018

Although mandatory reporting of suspected child abuse was first introduced over 50 years ago, there are no quantitative studies addressing whether or not it achieves better outcomes for children. We report two cases of maternal infection, one with tuberculosis (TB) and one with human immunodeficiency virus (HIV), where the mothers' failure to attend follow‐up appointments raised the possibility of significant harm if their infants were infected. Some health professionals argued strongly that mandatory reporting meant the mothers should be reported to child protection authorities. Others argued that the risk was not critically imminent and an immediate report could seriously compromise maternal confidentiality, risked maternal disengagement and a worse outcome. An alternative was to make more vigorous efforts to contact the mothers and report only if these failed. In the TB case, reporting to child protection was deferred in favour of making more strenuous efforts at communication, which proved successful. In the HIV case, a case worker reported the case to child protection, but when the doctor contacted child protection authorities they agreed not to contact the mother unless the doctor's vigorous attempts to communicate with her failed. We do not advocate for breaking the law regarding mandatory reporting, but we do argue for a considered approach to the timing of reporting and for a collaborative approach with child protection services.
Child with tongue fangs
Authors: Ganeshalingham Anusha , Artrip John , Ruygrok Peter
Published: November 2018

See Answer
Peri‐areolar dermatitis neglecta
Authors: Ghosh Sudip K , Sarkar Sharmila , Darung Ivoreen
Published: November 2018

See Answer
Characterization of the novel HLA‐B*15:476 allele by sequencing‐based typing
Authors: Ralazamahaleo Mamy , Elsermans Vincent , Top Isabelle , Guidicelli Gwendaline , Visentin Jonathan
Published: November 2018

HLA‐B*15:476 differs from HLA‐B*15:01:01:01 by one nucleotide substitution at codon 299 in exon 5.
A Robust Rate of Penetration Model for Carbonate Formation
Authors: Al-AbdulJabbar Ahmad , Elkatatny Salaheldin , Mahmoud Mohamed , Abdelgawad Khaled , Al-Majed Abdulaziz
Published: November 2018

During the drilling operations, optimizing the rate of penetration (ROP) is very crucial, because it can significantly reduce the overall cost of the drilling process. ROP is defined as the speed at which the drill bit breaks the rock to deepen the hole, and it is measured in units of feet per hour or meters per hour. ROP prediction is very challenging before drilling, because it depends on many parameters that should be optimized. Several models have been developed in the literature to predict ROP. Most of the developed models used drilling parameters such as weight on bit (WOB), pumping rate (Q), and string revolutions per minute (RPM). Few researchers considered the effect of mud properties on ROP by including a small number of actual field measurements. This paper introduces a new robust model to predict the ROP using both drilling parameters (WOB, Q, ROP, torque (T), standpipe pressure (SPP), uniaxial compressive strength (UCS), and mud properties (density and viscosity) using 7000 real-time data measurements. In addition, the relative importance of drilling fluid properties, rock strength, and drilling parameters to ROP is determined. The obtained results showed that the ROP is highly affected by WOB, RPM, T, and horsepower (HP), where the coefficient of determination (T2) was 0.71, 0.87, 0.70, and 0.92 for WOB, RPM, T, and HP, respectively. ROP also showed a strong function of mud fluid properties, where R2 was 0.70 and 0.70 for plastic viscosity (PV) and mud density, respectively. No clear relationship was observed between ROP and yield point (YP) for more than 500 field data points. The new model predicts the ROP with average absolute percentage error (AAPE) of 5% and correlation coefficient (R) of 0.93. In addition, the new model outperformed three existing ROP models. The novelty in this paper is the application of the clustering technique in which the formations are clustered based on their compressive strength range to predict the ROP. Clustering yielded accurate ROP prediction compared to the field ROP.
Optimal Analysis of Entropy Generation and Heat Transfer in Parabolic Trough Collector Using Green-Synthesized TiO2/Water Nanofluids
Authors: Okonkwo Eric C. , Abid Muhammad , Ratlamwala Tahir A. H. , Abbasoglu Serkan , Dagbasi Mustafa
Published: November 2018

This study presents an experimental nanoparticle synthesis and the numerical analysis of a parabolic trough collector (PTC) operating with olive leaf synthesized TiO2/water nanofluid. The PTC is modeled after the LS-2 collector for various operating conditions. An analysis of the heat transfer and entropy generation in the PTC is carried out based on the first and second laws of thermodynamics for various parameters of nanoparticle volumetric concentration (0 ≤ φ ≤ 8%), mass flow rate (0.1 ≤ m˙ ≤ 1.1 kg/s), and inlet temperatures (350–450 K) under turbulent flow regime. The effect of these parameters is evaluated on the Nusselt number, thermal losses, heat convection coefficient, outlet temperature, pressure drop, entropy generation rate, and Bejan number. The results show that the values of the Nusselt number decrease with higher concentrations of the nanoparticles. Also, the addition of nanoparticles increases the heat convection coefficient of the nanofluid compared to water. The thermal efficiency of the system is improved with the use of the new nanofluid by 0.27% at flow rates of 0.1 kg/s. The entropy generation study shows that increasing the concentration of nanoparticles considerably decreases the rate of entropy generation in the system. It is also observed that increasing the volumetric concentration of nanoparticles at low mass flow rates has minimal effect on the rate of entropy generation. Finally, a correlation that provides a value of mass flow rate that minimizes the entropy generation rate is also presented for each values of inlet temperature and nanoparticle volumetric concentration.
Experimental and Numerical Investigation of the Flow in a Trailing Edge Ribbed Internal Cooling Passage
Authors: Baek Seungchan , Lee Sangjoon , Hwang Wontae , Park Jung Shin
Published: November 2018

The flow field in a ribbed triangular channel representing the trailing edge internal cooling passage of a gas turbine high-pressure turbine blade is investigated via magnetic resonance velocimetry (MRV) and large eddy simulation (LES). The results are compared to a baseline channel with no ribs. LES predictions of the mean velocity fields are validated by the MRV results. In the case of the baseline triangular channel with no ribs, the mean flow and turbulence level at the sharp corner are small, which would correspond to poor heat transfer in an actual trailing edge. For the staggered ribbed channel, turbulent mixing is enhanced, and flow velocity and turbulence intensity at the sharp edge increase. This is due to secondary flow induced by the ribs moving toward the sharp edge in the center of the channel. This effect is expected to enhance internal convective heat transfer for the turbine blade trailing edge.
Study of the Stiffness Matrix of Preloaded Duplex Angular Contact Ball Bearings
Authors: Lin Shengye , Jiang Shuyun
Published: November 2018

This paper studies the stiffness characteristics of preloaded duplex angular contact ball bearings. First, a five degrees-of-freedom (5DOF) quasi-static model of the preloaded duplex angular contact ball bearing is established based on the Jones bearing model. Three bearing configurations (face-to-face, back-to-back, and tandem arrangements) and two preload mechanisms (constant pressure preload and fixed position preload) are included in the proposed model. Subsequently, the five-dimensional stiffness matrix of the preloaded duplex angular contact ball bearing is derived analytically. Then, an experimental setup is developed to measure the radial stiffness and the angular stiffness of duplex angular contact ball bearings. The simulated results match well with those from experiments, which prove the validity of the proposed model. Finally, the effects of bearing configuration, preload mechanism, and unloaded contact angle on the angular stiffness and the cross-coupling are studied systematically.
Two-Dimensional Arbitrarily Shaped Acoustic Cloaks With Triangular Patterns of Homogeneous Properties
Authors: Li Qi , Vipperman Jeffrey S.
Published: November 2018

Acoustic cloaking is an intriguing phenomenon that has attracted lots of attention. The required inhomogeneous and anisotropic properties of acoustic cloaks derived with transformation acoustics make them difficult to realize. In this paper, a new mapping relation is presented. An acoustic cloak can be divided into any number of arbitrary triangular patterns, which are mapped from similar patterns in virtual space. Transformation from one triangular domain to another leads to homogeneous properties using transformation acoustics. The resulting cloak is composed of homogeneous triangular parts, each having just two alternating layers of material. The manner of division of the cloak affects the properties of each triangular part dramatically, which can be leveraged to vary the properties of each triangular part for more realistic material properties. Simulations of models based on this method show good cloaking performance at reducing the reflected and scattered waves due to the cloaked obstacle.
A Thermo-Environmental Evaluation of a Modified Combustion Gas Turbine Plant
Authors: Khaliq Abdul , Habib M. A. , Choudhary Keshavendra
Published: November 2018

This paper reports the comprehensive thermodynamic modeling of a modified combustion gas turbine plant where Brayton refrigeration cycle was employed for inlet air cooling along with evaporative after cooling. Exergetic evaluation was combined with the emission computation to ascertain the effects of operating variables like extraction pressure ratio, extracted mass rate, turbine inlet temperature (TIT), ambient relative humidity, and mass of injected water on the thermo-environmental performance of the gas turbine cycle. Investigation of the proposed gas turbine cycle revealed an exergetic output of 33%, compared to 29% for base case. Proposed modification in basic gas turbine shows a drastic reduction in cycle's exergy loss from 24% to 3% with a considerable decrease in the percentage of local irreversibility of the compressor from 5% to 3% along with a rise in combustion irreversibility from 19% to 21%. The environmental advantage of adding evaporative after cooling to gas turbine cycle along with inlet air cooling can be seen from the significant reduction of NOx from 40 g/kg of fuel to 1 × 10−9 g/kg of fuel with the moderate increase of CO concentration from 36 g/kg of fuel to 99 g/kg of fuel when the fuel–air equivalence ratio reduces from 1.0 to 0.3. Emission assessment further reveals that the increase in ambient relative humidity from 20% to 80% causes a considerable reduction in NOx concentration from 9.5 to 5.8 g/kg of fuel while showing a negligible raise in CO concentration from 4.4 to 5.0 g/kg of fuel.
MEMS As a Continuous Time Recurrent Neuron (CTRN) Computing Unit
Authors: Alsaleem Fadi , Hasan Mohammad H. , Tesfay Mehari , Rafaie Mostafa
Published: November 2018

Smart analysis of sensory data in real time is growing more important by the advent of the internet of things (IoT). Currently, this demand is being met by microprocessors utilizing classical computing algorithms or using simple machine learning schemes; which, aside from their high computing power requirements, are projected to reach an imminent plateau as transistor shrinking is reaching a physical limit. In this paper, we show the potential of transforming the dynamics of micro-electro-mechanical system MEMS by activating electrical resonance to perform simple neurological processes, such as detection and memory, similar to those existing in recurrent neurons.
Data Clustering Using the Natural Bézier Functions
Authors: Venkataraman P.
Published: November 2018

An unorthodox and effective non-iterative procedure for spherical clusters is demonstrated in this paper. It uses natural Bézier functions to determine initial cluster locations using the content of the data. The natural Bernstein-Bézier functions are very robust in representing data through continuous functions in the application of functional data analysis. This paper demonstrates that they are equally robust at resolving data clusters in classification problems. The original data is scaled and segmented. A natural Bézier function is fitted for each segment and the initial clusters are centered at the function extremums that are distinctly located. A self-selection process based on least distance is used to assign the data to these initial cluster centers. A minimum membership count is imposed and nearby clusters are combined to reduce these initial cluster centers based on visual clues. Centroid recalculation and data reassignment can be used for centroid convergence. The method is demonstrated for two dimensional spherical clusters. This approach requires no iteration. Four examples from clustering benchmark datasets are used to showcase the method. The data include different numbers of clusters, different data density for the clusters, as well as different levels of overlap. This method is new and different from other data clustering methods available in the literature. It is better than the standard k-means clustering method since it does not require information on the number of clusters or cluster membership count. The method is non-iterative and does not require random initialization or distance optimization.
Statistical Tolerance Analysis With Sensitivities Established With Tolerance-Maps
Authors: Chitale Aniket N. , Davidson Joseph K. , Shah Jami J.
Published: November 2018

The purpose of math models for tolerances is to aid a designer in assessing relationships between tolerances that contribute to variations of a dependent dimension that must be controlled to achieve some design function and which identifies a target (functional) feature. The T-Maps model for representing limits to allowable manufacturing variations is applied to identify the sensitivity of a dependent dimension to each of the contributing tolerances to the relationship. The method is to choose from a library of T-Maps the one that represents, in its own local (canonical) reference frame, each contributing feature and the tolerances specified on it; transform this T-Map to a coordinate frame centered at the target feature; obtain the accumulation T-Map for the assembly with the Minkowski sum; and fit a circumscribing functional T-Map to it. The fitting is accomplished numerically to determine the associated functional tolerance value. The sensitivity for each contributing tolerance-and-feature combination is determined by perturbing the tolerance, refitting the functional map to the accumulation map, and forming a ratio of incremental tolerance values from the two functional T-Maps. Perturbing the tolerance-feature combinations one at a time, the sensitivities for an entire stack of contributing tolerances can be built. For certain classes of loop equations, the same sensitivities result by fitting the functional T-Map to the T-Map for each feature, one-by-one, and forming the overall result as a scalar sum. Sensitivities help a designer to optimize tolerance assignments by identifying those tolerances that most strongly influence the dependent dimension at the target feature. Since the fitting of the functional T-Map is accomplished by intersection of geometric shapes, all the T-Maps are constructed with linear half-spaces.
The Tolerance Coordination Design Method of Related Feature and Datum Features When Applying Material Condition
Authors: Wu Yuguang , Mei Zhiqian
Published: November 2018

When the datum features apply a material condition, the tolerance of a related feature must coordinate with its datum features. The tolerance coordination design of the related feature with its datum features is an important issue; an uncoordinated tolerance will give rise to an unnecessarily tight tolerance of a target geometrical feature or an invalid application of the material condition. In this paper, a coordination design method is proposed. The notion of the shift tolerance is used to establish the coordination relationship of the tolerance between the related feature and its datum features. The calculation mechanism of the shift tolerance for two datum features applying a material condition is described. To calculate the shift tolerance of the datum features, the datum feature simulator is used to construct the measurement coordinate system and the design coordinate system. For the different combination of two datum features applying a material condition, the relative motion of the design coordinate system with respect to the measurement coordinate system is represented by the parallel-crank mechanism, and the length of the crank is used to calculate the shift tolerance. Based on the shift tolerance, two criteria of the tolerance design at applying material condition are studied, one is the coordination guideline for the geometric tolerance of the related feature and the dimensional tolerance of the datum feature; the other criterion is the coordination guideline for the dimension tolerance between two datum features. Finally, two case studies are introduced to verify reasonableness of the proposed criteria and method.
A Quantitative Study on the Effects of Studio Art Training on Proficiency in Statics
Authors: Sullivan Gerald A. , Brown Julie Phillips , Hardin Jon-Michael
Published: November 2018

A study is described which seeks to quantify the benefits of studio art training on students’ analytical capabilities in a sophomore level statics course. Based on a drawing quality rubric developed for the study, it was shown that students’ drawings of a 3-D engineering system improved significantly after participating in a studio art module. Additionally, students who took part in the studio art module demonstrated better performance on a three-dimensional statics refresher problem than those who received no art training, six weeks after the studio art module was conducted.
Mechanical Representation and Stability of Dynamical Systems Containing Fractional Springpot Elements
Authors: Hinze Matthias , Schmidt André , Leine Remco I.
Published: November 2018

In this article we consider the Lyapunov stability of mechanical systems containing fractional springpot elements. We obtain the potential energy of a springpot by an infinite dimensional mechanical analogue model. Furthermore, we consider a simple dynamical system containing a springpot as a functional differential equation and use the potential energy of the springpot in a Lyapunov functional to prove uniform stability and discuss asymptotic stability of the equilibrium with the help of an invariance theorem.
Autonomous Untethered Flight of Multibody Dynamics Rotorcraft With Cycloidal Rotors
Authors: Gagnon Louis , Masarati Pierangelo
Published: November 2018

Multibody dynamics models of a helicopter and two cycloidal rotor aircraft concepts capable of vertical take-off and landing (VTOL) are constructed. The first concept aircraft is a helicopter equipped with two lateral cycloidal rotors acting as a replacement for its tail rotor and is named the Heligyro. The other concept is named the Quadricyclogyro and is propelled exclusively by four cycloidal rotors whose axes are aligned. The autopilot algorithm is implemented as a proportional, integral, and derivative (PID) controller and is tuned using a genetic optimization algorithm directly on the multibody models. Aircraft vibration and energy requirements are monitored and fed as penalty functions to the genetic algorithm. The time-domain responses of the aircraft attempting to follow mission paths of variable complexity obtained from the literature are studied. Overall, the tuned VTOL aircraft are able to reproduce the requested routes with good accuracy if a certain speed threshold is respected.
Design and Analysis of Manufacturing Component Under Sustainability Considerations: A Case Study of Electronic and Mechanical Indexing Head for Milling Operation
Authors: Jha Nand K. , Amin Mahmoud M.
Published: November 2018

An attempt has been made to design and analyze Indexing Head a very important component in milling operation under sustainability considerations. The design of each component of indexing head is presented along with solid modeling and finite element analysis. The cost estimation for indexing head for milling operation is also presented. The design and finite element analysis of indexing head should be utilized by manufacturers of this very useful device in milling operation. It is used for cutting gears, spirals, splines, etc. The cost estimated of the manufactured indexing head shows it to be within reasonable limits of market. Finite element analysis of each component is safe. An electronic indexing is suggested as an improvement over the mechanical indexing head. A schematic of electronic indexing is presented. The electronic indexing head can be used with milling machine not provided with indexing head and will be portable. The minimum energy needed to manufacture the indexing head is also estimated.
Vibration Analysis and Experimental Validation of Multiple Launch Rocket System Based on MSTMM
Authors: Wang Guoping , Tu Tianxiong , Rui Xue , Miao Yunfei , Rui Xiaoting
Published: November 2018

Natural vibration characteristics and dynamics response of multiple launch rocket system (MLRS) are of fundamental importance from the viewpoint of vibration levels, firing dispersion, and stability. In this study, a new launch vehicle-supports-rockets coupling dynamic model for a practical MLRS is established. Rui method, namely the transfer matrix method for multibody systems (MSTMM) is a new and efficient method for multibody system dynamics (MSD) and is used to obtain the vibration characteristics and dynamics response. The dynamics model, the topology figure of dynamics model, the transfer equations of elements, the overall transfer equation, the eigenfrequency equation, the body dynamics equations, the generalized coordinate equations, and the dynamics simulation system for the MLRS are established. Based on the advantages of MSTMM in studying MSD, the vibration characteristics and dynamics response of complex MLRS are computed rapidly. Finally, the new model is validated in three ways: (1) modal experiment of MLRS, (2) launch dynamics experiment of non-full loading rockets, and (3) launch dynamics experiment of full loading rockets. The results show that the proposed model can not only simulate the natural vibration characteristics of the MLRS but also effectively perform dynamic simulations of the MLRS during launching process.
Energy Consumption and Total Vehicle Efficiency Calculation Procedure for Electric Vehicles (EV, HEV and PHEV)
Authors: Alcázar-García Désirée , Romeral Martínez Luis
Published: November 2018

An important question regarding vehicles design optimization and environmental care are energy management strategy and efficiency determination.

Automotive brands work with a wide range of technologies and electrified mobility is considered to be one of the solutions to the growing environmental question. The present paper develops a mathematical model to predict the light-duty electric vehicle overall consumed energy depending on architecture and configuration of vehicles with different degrees of electrification (e.g. electric vehicle and hybrid electric vehicle), on the type of electric motor (e.g. hybrid synchronous electric motor, permanent magnet motor or induction motor) and engine (e.g. gasoline (Otto or Atkinson) or Diesel), on technology of energy-storage system (e.g. lithium-ion or nickel-metal hydride battery) and on weight and geometry of the car being flexible drive cycles and for all types of wheel drive (four wheel, front and rear). The method is verified making a component-to-component revision through real automobiles that are available in the market to demonstrate the validity of the system.
Velocity Decomposition-Enhanced Control for Point and Curved-Foot Planar Bipeds Experiencing Velocity Disturbances
Authors: Fevre Martin , Goodwine Bill , Schmiedeler James P.
Published: November 2018

This paper extends the use of velocity decomposition of underactuated mechanical systems to the design of an enhanced hybrid zero dynamics (HZD)-based controller for biped robots. To reject velocity disturbances in the unactuated degree of freedom, a velocity decomposition-enhanced controller implements torso and leg offsets that are proportional to the error in the unactuated velocity. The offsets are layered on top of an HZD-based controller to preserve simplicity of implementation. Simulation results with a point-foot, three-link planar biped show that the proposed method has nearly identical performance to transverse linearization feedback control and outperforms conventional HZD-based control. Curved feet are implemented in simulation and show that the proposed control method is valid for both point-foot and curved-foot planar bipeds. Performance of each controller is assessed by 1) the magnitude of the disturbance it can reject by numerically computing the basin of attraction, 2) the speed of return to nominal step velocity following a disturbance at every point of the gait cycle, and 3) the energetic efficiency, which is measured via the specific cost of transport. Several gaits are analyzed to demonstrate that the trends observed in 1) through 3) are consistent across different walking speeds.
Design and Test of Wireless Communication System in Tractor Traction Performance Testing
Authors: Yan Xianghai , Li Zhongli , Zhou Zhili
Published: November 2018

By designing a multicomputer wireless communication function for the traditional tractor traction performance test system, the complexity of the physical connection is reduced. The mobility of the test system is enhanced. An analog channel of the data collector is been detected. The maximum input error of traction channel is 3mV, and the linearity is 0.06%. An experimental study on the static and dynamic performances of the wireless communication system is carried out. The results of static test show that the system is reliable in data transfer under better communication condition. The maximum valid transmission distance is 520m. The results of dynamic test show that the data is real-time acquired, displayed, exchanged and managed making use of the wireless communication system in the 15m range. The system is without the Doppler frequency shift and shadow effect. The bit error rate of the data transmission is 0. The system update frequency is 10Hz. The tractive characteristic curves got from wire test are consistent with the curves got from wireless test, which proves that the reliability of the wireless communication system.
Research and Experiment for Loading Control System of Power Wagon
Authors: Yan Xianghai , Zhou Zhili , Li Zhongli
Published: November 2018

At present, the power wagon is confronted with several problems: small brake torque at low speeds, output instability of random loading and slow response speed. Aiming at the existing problems of current control performance for loading system of power wagon, the paper proposes a back propagation (BP) neural net PID algorithm. The dynamic analysis of power wagon loading system was presented. A mathematical model of the loading system is established by use of the classical control theory. Through simulation and analysis, the dynamic response of the loading system is researched by using step signal, sine signal and field-load spectrum stochastic signal as system input respectively. Meanwhile, through MATLAB simulation experiment, compares and analysis with superiorities and characteristics between BP neural net PID control method and traditional PID control method. On the basis of this study, the power wagon was modified based on YTO-LX1304. The road test of the YTO-MF554 tractor traction property was performed on the concrete by using the power wagon. Experimental results show that the system output traction has a good follow effect in comparison with input load. The BP neural net PID algorithm can improve the system’s dynamical performance and its static accuracy in comparison with the traditional PID control. The simulation results show that system delay time is 0.12s and maximum overshoot is 3.8%. Road test results show that system delay time is 0.22s and maximum overshoot is 4.2%. The BP neural net PID algorithm has better control performance for second-order plant with time-delay time-varying system.
Electromechanical Design of Robotic Transfemoral Prostheses
Authors: Laschowski Brock , Andrysek Jan
Published: November 2018

Alongside promising advances in biomechatronics, the following research presents the first documented investigation reviewing the electromechanical system designs of energetically-powered (i.e., robotic) prostheses for patients with transfemoral amputations. The technical review begins with examining the material and mechanical designs, and electrical batteries incorporated into robotic transfemoral prostheses. The actuation systems have encompassed electromagnetic actuators (i.e., occasionally featuring series elastic elements), pneumatic actuators (i.e., pneumatic cylinders and pneumatic artificial muscles), and hydraulic actuators. Various wearable sensors have been utilized to provide closed-loop feedback control, including electromechanical sensors, surface electromyography, and bioinspired machine vision systems. The Össur Power Knee (i.e., the only commercially-available powered transfemoral prosthesis) is additionally discussed. The technical review concludes with suggesting prospective future directions for innovation, specifically lower-limb prostheses capability of electrical energy regeneration.
Design of Constant-Force Mechanisms Based on Straight-Line Linkages
Authors: Huang Hsin-Ting , Kuo Chin-Hsing
Published: November 2018

This paper presents two novel constant-force mechanisms (CFMs) based on Scott-Russell and Hart’s straight-line linkages with mechanical springs. By articulating either two compression springs (type C-C) or one compression spring with another one extension spring (type C-E) onto each of these two CFMs, the point(s) which trace straight-line trajectories can illustrate a constant force within the mechanism workspace. We also show that the preload of the extension spring for type C-E CFMs will not affect its constant-force property but can define the amount of the output force. The proposed concepts of CFMs are relatively simple and concise, which could be useful for the complex mechanical systems that request a constant output force. A constant-force robotic gripper is illustrated by using the proposed Scott-Russell-type CFM.
Programmable Constant-Force Multistable Mechanisms
Authors: Zanaty Mohamed , Henein Simon
Published: November 2018

Programmable multistable mechanisms exhibit stability behavior whereby the stiffness and the number of stable states can be controlled via programming inputs. In this paper, we report the zero stiffness behavior of a 2-degree of programming (DOP) T-combined, axially loaded double parallelogram multistable mechanism. We demonstrate zero force monostability, constant force monostability, zero force bistability, constant force bistability and zero force tristability behaviors by tuning the programming input. We derive analytically the reaction force of the mechanism for each configuration and verify our analytical results using numerical simulations and experimental measurements, showing less than 10% discrepancy. The concept of constant-force programming can be extended to N-DOP T-combined, serial combined and parallel combined programmable multistable mechanisms. Finally, we present potential applications of stability programming.
Cutting Tool Wear Estimation Using a Genetic Algorithm Based Long Short-Term Memory Neural Network
Authors: Yu Wennian , Mechefske Chris K. , Kim Il Yong
Published: November 2018

On-line cutting tool wear monitoring plays a critical role in industry automation and has the potential to significantly increase productivity and improve product quality. In this study, we employed the long short-term memory neural network as the decision model of the tool condition monitoring system to predict the amount of cutting tool wear. Compared with the traditional recurrent neural networks, the long short-term memory (LSTM) network can capture the long-term dependencies within a time series. To further decrease the training error and enhance the prediction performance of the network, a genetic algorithm (GA) is applied to find the initial values of the networks that minimize the objective (training error). The proposed methodology is applied on a publicly available milling data set. Comparisons of the prediction performance between the Elman network and the LSTM with and without using GA optimization proves that the GA based LSTM shows an enhanced prediction performance on this data set.
Achieving Simplicity: Development and Design of Simple Products
Authors: Pilz Fabian , Vajna Sándor , Schabacker Michael
Published: November 2018

Increasing requirements on today’s products, as well as possibilities resulting from globalization and digitization, lead to a growth of increasingly complex products. However, design principles from the field of design engineering call for a product to be designed as simple as possible. It is not yet clear what characteristics and properties a simple product has. The aim of this paper is to clarify the different definitions of simplicity in different disciplines within the product lifecycle and to provide a general description of a simple product from the viewpoint of the different groups.
Design of Disposable 3D Printed Surgical End-Effectors for Robotic Lumbar Discectomy Procedures
Authors: Johnson Benjamin V. , Gong Zekun , Cole Brian A. , Cappelleri David J.
Published: November 2018

In this paper, the design of disposable 3D printed surgical end-effectors for robotic lumbar discectomy is presented. Discectomy is the surgery to remove the herniated disc material that is pressing on a nerve root or spinal cord. This surgery is performed to relieve pain or numbness caused by the pressure on the nerve. The limited workspace of the spine (< 27 cm3) results in challenging design requirements for surgical instruments. We propose a new cannula-based robotic lumbar discectomy procedure that can accommodate multiple articulated tools in the workspace at the same time and can be controlled teleoperatively by the surgeon. We present designs for two instruments for this proposed system: an articulated nerve retractor and an articulated grasper. The end-effectors of each are 3D printed with multiple materials, with flexible links acting as joints of the mechanism. These flexible links are actuated by cables which provide sufficient articulation and manipulation forces in the surgical workspace. The end-effector’s articulated flexible joint kinematics is modeled and tested for range of motion capabilities. The retraction forces for the nerve retractor and the grasping force for the grasper are also experimentally tested and verified to meet all the design requirements. Additionally, fatigue testing of the flexible joint is presented and teleoperated control for the instruments is demonstrated.
Generating Technology Evolution Prediction Intervals With Bootstrap Method
Authors: Zhang Guanglu , Allaire Douglas , McAdams Daniel A. , Shankar Venkatesh
Published: November 2018

Technology evolution prediction, or technological forecasting, is critical for designers to make important decisions during product development planning such as R&D investment and outsourcing. In practice, designers want to supplement point forecast by prediction intervals to assess future uncertainty and make contingency plans. Available technology evolution data is a time series but is generally with non-uniform spacing. Existing methods associated with typical time series models assume uniformly spaced data, so these methods cannot be used to construct prediction intervals for technology evolution prediction. In this paper, we develop a generic method that use bootstrapping to generate prediction intervals for technology evolution. The method we develop can be applied to any technology evolution prediction model. We consider parameter uncertainty and data uncertainty and establish their empirical probability distributions. We determine an appropriate confidence level α to generate prediction intervals through a holdout sample analysis rather than set α = 0.05 as is typically done in the literature. We validate our method to generate the prediction intervals through a case study of central processing unit transistor count evolution. The case study shows that the prediction intervals generated by our method cover every actual data point in a holdout sample test. To apply our method in practice, we outline four steps for designers to generate prediction intervals for technology evolution prediction.
Prototyping and Validation of a Fixed-Actuator 3-Leg 6-DOF Robot
Authors: Jensen Nathan A. , Nelson Carl A.
Published: November 2018

While 6-leg, 6 DOF parallel robots offer advantages over serial mechanisms in many applications, they suffer from mobility limitation pertaining to both the maximum extension of links and link interference. The latter of these can be mitigated by a reduction of the number of links in the mechanism. The end-effector’s degrees of freedom are maintained by adding controllable degrees of freedom to the remaining legs. This paper presents a prototype of a previously proposed 3-leg, 6-DOF parallel robot. A measure of its workspace is also shown and compared to that of a similarly sized 6-leg parallel mechanism. Analysis of partial derivatives of Cartesian points with respect to joint angles is also explored to give a metric of expected performance in different regions of workspace.
Analysis of Sliding Mode Observers for Nonlinear Systems Using a Time-Averaged Lyapunov Function
Authors: Mehta Sagar , Vijayaraghavan Krishna
Published: November 2018

This paper is an extension of the authors’ previous paper on the analysis of sliding mode observers using a novel Time-Averaged Lyapunov function [1]. The paper presents the design of a sliding mode observer for a Lipschitz nonlinear system. The paper demonstrates that the external sensor noise (Gaussian) only affects the convergence rate of the observer without having any influence over its stability at steady state. Further, a condition for the existence of the observer is provided in the form of an LMI. The LMI can be solved offline using various commercial LMI solvers. An illustrative example is presented to demonstrate the effectiveness of this approach.
An Analysis of Modularity As a Design Rule Using Network Theory
Authors: Walsh Hannah S. , Dong Andy , Tumer Irem Y.
Published: November 2018

Increasing the modularity of system architectures is generally accepted as a good design principle in engineering. In this paper, we explore whether modularity comes at the expense of robustness. To that end, we model three engineering systems as networks and measure the relation between modularity and robustness to random failures. We produced four types of network models of systems — component, component-function, component-parameter, and function-parameter — to further test the relation of robustness to the type of system representation, architectural or behavioral. The results show that higher modularity is correlated with lower robustness (p < 0.001) and that the estimated modularity of the system can depend on the type of system representation. The implication is that there is a trade-off between modularity and robustness, meaning that increasing modularity might not be appropriate for systems for which robustness is critical and for those whose modularity estimate differs largely between each type of system representation.
Kinematics Analysis and Motion Control of a Mobile Robot Driven by Three Tracked Vehicles
Authors: Liu Xin-Jun , Gong Zhao , Xie Fugui , Shentu Shuzhan
Published: November 2018

In this paper, a mobile robot named VicRoB with 6 degrees of freedom (DOFs) driven by three tracked vehicles is designed and analyzed. The robot employs a 3-PPSR parallel configuration. The scheme of the mechanism and the inverse kinematic solution are given. A path planning method of a single tracked vehicle and a coordinated motion planning of three tracked vehicles are proposed. The mechanical structure and the electrical architecture of VicRoB prototype are illustrated. VicRoB can achieve the point-to-point motion mode and the continuous motion mode with employing the motion planning method. The orientation precision of VicRoB is measured in a series of motion experiments, which verifies the feasibility of the motion planning method. This work provides a kinematic basis for the orientation closed loop control of VicRoB whether it works on flat or rough road.
FRAME-Sim: A Free-Software, Multibody-Based, Pilot in the Loop Rotorcraft Flight Simulator
Authors: Zanoni Andrea , Conti Luca , Masarati Pierangelo
Published: November 2018

In the context of a modern approach to the design of rotocraft, handling qualities should be the result of careful planning, rather than the output of a multitude of other choices, made primarily focusing on more immediate constraints. For a wide range of flight conditions and mission task elements, the test pilot feedback is the essential measure upon which the design choices are made. Thus, it is becoming of fundamental importance to be able to simulate a representative model of the vehicle in a pilot-in-the-loop environment as early as possible in the design stage. This work is intended to document the development process of one such system currently being realized at the facilities belonging to the Aerospace Science and Technology Department of Politecnico di Milano. Particular attention is given to the software architecture, based on the free and open-source multibody solver MBDyn. The development of a module specifically designed to exploit the environment visualization capabilities of FlightGear, also a free and open-source software, is presented.
Workspace Investigation of Cable-Driven Robots With Non-Negligible Cable Mass and Antipodal Method
Authors: Notash Leila , McColl Derek
Published: November 2018

The significance of gravity, cable density and elasticity on cable tension and manipulator workspace is investigated. Formulations of the cable tension vector are discussed. In addition, implementation of the antipodal theorem criteria for the workspace boundary characterization of planar cable-driven robot manipulators is presented when the mass and elasticity of cables are included. It is demonstrated that unlike the linear model, the external force could have more prominent effect on the workspace. Specifically, depending on the cable properties, platform orientation and manipulator design constraints, for the catenary cable model, the extended workspace due to external wrench may be divided into disjoint regions.
Optimizing Function-Based Fault Propagation Model Resilience Using Expected Cost Scoring
Authors: Hulse Daniel , Hoyle Christopher , Goebel Kai , Tumer Irem Y.
Published: November 2018

Complex engineered systems are often associated with risk due to high failure consequences, high complexity, and large investments. As a result, it is desirable for complex engineered systems to be resilient such that they can avoid or quickly recover from faults. Ideally, this should be done at the early design stage where designers are most able to explore a large space of concepts. Previous work has shown that functional models can be used to predict fault propagation behavior and motivate design work. However, little has been done to formally optimize a design based on these predictions, partially because the effects of these models have not been quantified into an objective function to optimize. This work introduces a scoring function which integrates with a fault scenario-based simulation to enable the risk-neutral optimization of functional model resilience. This scoring function accomplishes this by resolving the tradeoffs between the design costs, operating costs, and modeled fault response of a given design in a way that may be parameterized in terms of designer-specified resilient features. This scoring function is adapted and applied to the optimization of controlling functions which recover flows in a monopropellant orbiter. In this case study, an evolutionary algorithm is found to find the optimal logic for these functions, showing an improvement over a typical a-priori guess by exploring a large range of solutions, demonstrating the value of the approach.
Understanding the Importance of Capturing Climate and Occupancy Trends During Concept-Stage Sustainable Building Design
Authors: Lin Sean , Albarhami Bahaa , Mayoral Salvador , Piacenza Joseph
Published: November 2018

This paper presents a comparison of concept stage computational model predictions to capture how building energy consumption is affected by different climate zones. The California State University, Fullerton (CSUF) Student Housing Phase III, which received a Platinum Leadership in Energy and Environmental Design (LEED) certification for the Building Design and Construction category, and its performance in a LEED California Nonresidential Title 24 (NRT24) and ASHRAE 90.1 climate zones is used as a case study to illustrate the method. Through LEED approved simulation software, the standard compliant energy simulation models are compared to the occupancy scheduled models along with the actual energy consumption in different climate zones. The results provide insight to how variables within student dormitory life affect total building energy usage. Total amount of energy consumed per area is one new factor providing understanding into occupancy trends. This new data set reveals more understanding regarding how and where the energy is consumed to maintain a comfortable learning environment.