bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of advanced intravenous conscious sedation techniques in complex oral surgery procedures: Comparison of midazolam, midazolam‐propofol and midazolam‐propofol‐alfentanil combinations
Authors: Offord David J. , Kingsford Nicola M. , Paterson Ross , Mather Craig I. , Robb Nigel D.
Published: November 2021

Aim

This retrospective observational study evaluates the safety and efficacy of intravenous sedation using midazolam only or combinations of two or three drugs including propofol and alfentanil for complex dental surgery such as implant placement or sinus augmentations.

Methods

The study analyses 60 patients aged 42–79 who required advanced sedation techniques for complex oral surgery procedures. Twenty patients had midazolam only (M), 10 patients a 2‐drug combination of midazolam and propofol (MP) and a third group of 30 patients had the combination of midazolam, propofol and alfentanil (MAP). The last two regimens were carried out under the supervision of a dedicated consultant anaesthetist.

Results

Higher mean minimum heart rate (beats/min) was observed in the midazolam group compared to the group sedated with the three‐drug regimen (p < 0.05). The time between the last drug administration (LDA) and end of surgery (EOS) was significantly longer (p < 0.005) in group M (≤45 mins) compared to the other two sedation groups MP and MAP (≤15 min). The final titration of midazolam of 11.2 ± 4 mg (5–20 mg) was significantly greater in group M than in either of group MP or MAP (p < 0.05).

Conclusion

In patients requiring conscious sedation to undergo complex and lengthy oral surgery, a combination of agents (midazolam, propofol and alfentanil) can provide a predictable steady state of sedation up to the end of the surgery resulting in better operating conditions for the surgeon and improved patient co‐operation. The shorter duration of action drugs propofol and alfentanil improved haemodynamic stability, sedation quality and reduce the final doses of each sedative agent.
Capnodynamics—Measuring cardiac output via ventilation
Authors: Karlsson Jacob , Lönnqvist Per‐Arne
Published: November 2021

Recent studies have identified stable hemodynamics as a contributing factor to improve outcome in pediatric anesthesia. So far, most of the hemodynamic monitoring methods applied in children have been complex to apply and often not satisfactory validated. Standard mainstream carbon dioxide analysis in combination with real‐time mathematical analysis of the measured capnography data has enabled the development of dynamic capnography, a non‐invasively cardiac output monitoring method that can be applied without user practice or need for calibrations. Capnodynamic cardiac output assessment has been extensively validated against gold standard reference methods, both in experimental and clinical settings. This review will describe the principle behind dynamic capnography measurement of cardiac output and mixed venous oxygen saturation. Additionally, the methods limitations and challenges when applied in children will be delineated.
How Ostrom's design principles apply to large‐scale commons: Cooperation over international river basins
Authors: Shin Geiguen
Published: November 2021

Many conventional studies on common‐pool resources (CPRs) have examined the governance of local resources such as fisheries, forests, grazing systems, irrigation systems, agriculture, water resources, and land tenure. However, a limited selection of recent studies has been interested in large‐scale commons such as climate change, air pollution, and transboundary disputes. Despite Ostrom's design principles (DPs) providing a robust framework for solving CPR problems, there have been relatively few empirical challenges examining the effect of DPs on CPRs, especially in the large‐scale commons. This paper examines how Ostrom's DPs are applied to international commons that may cause complicated disputes among states. The case being studied is international rivers as international commons. Based on binary logit analysis, this research found that four of Ostrom's DPs—clear boundary, operational rules, monitoring system, and multi‐level governance—are positively associated with success in managing the international river commons (IRCs) as a CPR. Additionally, the results from fuzzy‐set Qualitative Comparative Analysis (QCA) partially indicate that the co‐occurrence of monitoring, conflict mechanisms, and multi‐level governance would lead to more successful IRCs.
Dynamic Buckling of 1-DOF Autonomous Potential Systems Under Tilted Cusp Catastrophe
Authors: Kounadis Anthony N.
Published: November 2021

Nonlinear dynamic buckling of one-degree-of freedom (1-DOF) undamped systems under step loading (autonomous systems) of constant direction and infinite duration is discussed in detail using Catastrophe Theory. Attention is focused on the relation of static cuspoind catastrophes to the corresponding dynamic catastrophes for 1-DOF autonomous undamped systems by determining properly the dynamic singularity and bifurcational sets for such systems. Using local analysis one has to classify first the total potential energy (TPE) function of the system into one of the elementary Thom’s catastrophes by defining the corresponding control (unfolding) parameters. Subsequently, using global analyses one can readily obtain exact results for the dynamic buckling loads (DBLs) and their imperfection sensitivity of systems subjected to dynamic dual cusp and tilted cusp catastrophes. It was found that the maximum DBL of the dynamic tilted cusp catastrophe corresponds to a limit point lying in the vicinity of the hysteresis point (related to the static tilted cusp catastrophe). Numerical examples illustrate the methodology proposed herein.
Free Lateral Vibration of Columns and Beams With Arbitrary Thin-Walled Cross Sections
Authors: Bert Charles W.
Published: November 2021

This paper surveys the literature on vibration of axially loaded beams in general, and thin-walled, open-section beams with and without axial load. Finally, for what is believed to be the first time, a solution is presented for the problem of vibration of a thin-walled beam subject to transverse preload.
Anisotropic Elasticity and Multi-Material Singularities
Authors: Yin Wan-Lee
Published: November 2021

Multi-material wedges associated with convergence of geometrical and material discontinuity generally show singular stress fields. Under a temperature load, the different sectors of the wedge experience incompatible thermal expansions. Jumps of the tangential thermal strains across the various radial interfaces of the wedge may be compensated by a suitable particular solution. The remote boundary condition are then taken care of by combining the particular solution with various eigensolutions of the wedge. In this work, a general scheme is developed for constructing particular solutions of arbitrary multi-material wedges under uniform temperature loads. These closed-form particular solutions generally contain terms with logarithmic dependence on the radial coordinate r. The solution scheme also yields particular solutions when the loading on the multi-material wedge is a uniform strain ϵz in the out-of plane direction.
Damage Initiation in Bonded Particulate Networks: 3D Simulations
Authors: Berhan L. , Wang C.-W. , Sastry A. M.
Published: November 2021

Several promising Li-ion technologies incorporate micro- and nanoarchitectured carbon networks, typically in the form of whisker/particle blends bonded with thermoplastic binders, in the electrodes. Degradation of these battery electrode materials is currently a persistent problem, with damage presenting as blistering and/or delamination. We are investigating bonding in micro- and nanostructured materials in order to predict onset of this degradation of these stochastic materials. Here, we describe a general methodology in modeling the small junctures in these porous network materials. We have found previously that the joint properties are the controlling feature in a significant class of materials, and suggest that 3D simulations on the bonds may be used in 2D simulations of overall network behavior.
An Analytical Study of Post-Buckling of Debonded One-Dimensional Sandwich Plates
Authors: Sankar Bhavani V. , Sylwan Màrten
Published: November 2021

An analytical method is developed to study the problem of one-dimensional sandwich plates containing debonded face-sheets and subjected to in-plane compressive loads. The non-linear governing equations for the sandwich plate are solved to obtain a relation between the boundary forces and displacements in a matrix form as in the finite element method. The debonded sandwich plate is divided into four elements. The element stiffness matrices are assembled to obtain the global stiffness matrix, and the global equations are solved to obtain the displacements. The results include load/end-shortening relations. The method is found to be very efficient and accurate, and can be used to study the progressive damage of debonded sandwich plates under in-plane compressive loads.
Effect of Loading Conditions on Deformation and Failure of Composite Sandwich Structures
Authors: Daniel Isaac M. , Gdoutos Emmanuel E. , Abot Jandro L. , Wang Kuang-An
Published: November 2021

An investigation was conducted of failure modes and criteria for their occurrence in composite sandwich columns and beams. The initiation of the various failure modes depends on the material properties of the constituents (facings and core), geometric dimensions and type of loading. The loading type or condition determines the state of stress throughout the sandwich structure, which controls the location and mode of failure. The appropriate failure criteria at any point of the structure account for the biaxiality or triaxiality of the state of stress. The specimens were made of unidirectional carbon/epoxy facings and aluminum honeycomb and PVC closed-cell foam cores. The constituent materials were fully characterized and, in the case of the foam core, failure envelopes were developed for general two-dimensional states of stress. Sandwich specimens were loaded under bending moment, shear and axial loading and failure modes were observed and compared with analytical predictions. The failure modes investigated are face sheet compressive failure, adhesive bond failure, indentation failure, core failure and facing wrinkling. The transition from one failure mode to another for varying loading or state of stress was discussed. Experimental results were compared with analytical predictions.
Some Results and Issues in the Non-Destructive Evaluation of Sandwich Composite Structures
Authors: Ayorinde Emmanuel O. , Gibson Ronald F. , Deng Feizhong
Published: November 2021

This paper focuses on the use of basic NDE methods like ultrasonics, imaging and vibration testing to assess the integrity of some sandwich composites which have been subjected to transverse loading. Samples of a foam core, glass composite facing sandwich beam of varying thicknesses and end notch lengths were tested in three point bending and assessed by these NDE methods. The results show that core shear and indentation failures appear to be the prominent failure modes for these geometries and materials, and that changes in the damping and vibration modal frequencies of the beams can indicate damage states.
Light Weight Steel Technology Used in a Vehicle Design: Safety CAE Analysis
Authors: Alwan Jamil M. , Wu Chi-Chin , Sheng Thomas H. , Li Chunhui (Kevin) , Liu Yi
Published: November 2021

The automotive industry is facing new environmental requirements that call for more stringent rules to protect the environment and reduce material and resources usage. As such, the automotive industry is in more need to reduce fuel consumption and control emissions in order to meet the new environmental requirements. One of the methods that helps in acheiving lower fuel consumption targets is weight reduction. Making cars lighter sounds plausable, but is it acheivable without affecting vehicle Safety as well as other customer demands for more comfort and better vehicle performance (Criteria that are a must in today’s stringent safety requirements and competitive environment.). The body-in-white (BIW) accounts for about 25% of the total vehicle weight, and thus it provides a great opportunity for weight reduction. However, the challenge is not only to reduce the vehicle’s BIW weight, but also to maintain competitive vehicle functionality in Safety, NVH and Durability.

The studied technologies include: Generic Body Architecture, Tailor Welded Blanks, Ultra High Strength Steel, Structural Foams, and Structural Adhesives. Each of these technologies was benchmarked in terms of weight savings, vs Safety, NVH, and Durability functionalities. The models that were used for the technology prove outs are based on generic modified Body Architecture CAE models. It was shown that the total weight savings acheived from architecture alone was 24 lb (out of 707 lb initial BIW weight, thus making the weight savings close to 3.4%). In addition, the combination of Tailor welded blanks and Ultra high strength steel has resulted in an 80 lb reduction in the BIW weight, which is close to 11.3%. Structural foams showed an effective increase in roof crush strength, and showed potential enhancement for frontal crash pulses as well as potential shortening of front ends. On the other hand, structural adhesives showed enormous NVH benefits in stiffness with as little as 1% energy absorption enhancement for crash. Thus producing the perfect method to compensate the reduced body stiffness due to sheet metal gage reduction and replacement with Ultra High strength steel. By such both safety and NVH functionalities are complemented without weight increase.
Front-End Structural Crash Energy Management Concept for a Sport Utility Like Aluminum Vehicle
Authors: Baccouche Mohamed R. , Wagner David A. , Chen Xiaoming , Mahmood Hikmat F.
Published: November 2021

Front-end structural concepts used to enhance the crash energy management of a sport utility like aluminum vehicle are discussed in this paper. These structural concepts were applied to the front-end rails, subframe, and subframe extension. Epoxy-based foam reinforcement was applied to the 5754 aluminum front end rails, shearing was applied to the cast-hydro formed tubular subframe, and a new load path was implemented in the front end structure in the form of a subframe extension. Deceleration-time response was developed and benchmarked against target double plateau square pulse at the early stage of the design. Vehicle front-end design and analysis for US-NCAP 35 mph full frontal crash were conducted using concept and detailed nonlinear finite element codes. Concept modeling tools that were used in the initial design stages involve collapsible nonlinear beam finite element, strength and stability, and spring mass system codes. Detailed finite element code RADIOSS was applied to the analysis of the final front-end structural design.

Occupant responses and injury numbers were evaluated using MADYM03D rigid body and finite element code. Concept vehicle crash safety protection was evaluated and star-rated then benchmarked against 2000 and 2001 production SUVs. A paper study was conducted on a higher strength less ductile 6111T6 stamped aluminum alloy to further enhance the structure and enhance dash and floor intrusion. Structural collapse mode, deceleration-time response, and occupant simulation results show a good performance of aluminum front-end structures in managing crash energy and protecting vehicle occupants.
Developing New Methods of Improving Design Productivity by Focusing on Transitions Between Working Situations
Authors: Kristensen Kjetil , Hildre Hans Petter
Published: November 2021

This paper gives an overview of the mechanisms behind transitions between working situations, and how effective transition mechanisms influence designer productivity. Effective transitions between working situations are based on knowledge conversion between tacit (implicit) and explicit (formalized) knowledge. Closing ongoing tasks represents micro-externalization or a conversion from tacit to explicit knowledge, and opening (new) tasks represents the reversed sequence, internalization, from explicit to tacit knowledge. These transitions assist the designer in shifting between different tasks, where knowledge that has been formalized makes the designer capable of starting the new task quicker than he or she would have been able to without the prior externalization process. Transitions between working situations can be divided into controlled transitions and forced transitions, where forced transitions are initiated by some external need, disturbance or interruption. It becomes increasingly important to pay attention to what mechanisms these different transitions represent, and how to manage them.
Anti-Hair Snare Pool Drain Cover
Authors: Barnett Ralph L. , Poczynok Peter J.
Published: November 2021

A drain cover for swimming pools, spas and hot tubs has been designed which addresses eight hazards associated with conventional drain systems. This new drain cover, illustrated in Figure 1, eliminates hair entanglement, child evisceration and finger entrapment as well as minimizing body entrapment. Furthermore, its design and construction provide effective countermeasures against vandalism, broken drain covers, missing drain covers and structural deterioration due to environmental antagonists. Additional features unrelated to safety include a universal fastening system which adapts the cover to all circular main drains available in the United States. Also, the drain cover is an order of magnitude stronger than its competitors and has a safe flow rate that is 37% greater than its nearest competitor’s. The product has been manufactured using a PVC material that is the most resistant formulation currently known for counteracting the effects of ultraviolet radiation and chlorine and other chemicals typically found in pools. This paper presents an anatomy of the product’s development.
Development of Intelligent Hierarchical Control for a Hydraulic Manipulator
Authors: Rahbari Roya , deSilva Clarence W.
Published: November 2021

This paper presents the development of a hierarchical intelligent controller for a hydraulic manipulator, which has been designed to be an integral part of an automated machine for mechanical processing of salmon. The developed controller for this hydraulic actuator is a three-layer hierarchical system. In the bottom layer of the hierarchy, a conventional proportional plus derivative (PD) controller is used to control the position of the cutting blade. The middle layer monitors the performance of the manipulator, preprocesses the response signals, and extracts the performance parameters, based on a step-input response. The top layer infers the tuning actions for the PD servo. The knowledge base for tuning the low level controller has been developed and represented by fuzzy rulesbase modules. The development of this hierarchical control system is discussed and some experimental results are given.
Experimental Joint Control Studies With a Flexible Two-Link System
Authors: Xu Wenwei , Zhang Xiaoping , Nair Satish S.
Published: November 2021

This paper investigates experimentally an adaptive control design for a flexible two-link system considering joint angle control in the presence of system uncertainties. The system uncertainties are treated as unknown bounded continuous functions of the states and a Gaussian network is used to map the uncertainties. Experiment results show the effectiveness of the proposed learning control strategy.
Neural-Based Remote Health Assessment and Failure Diagnostics
Authors: Shoureshi Rahmat A. , Terry Benjamin
Published: November 2021

As industrial competition intensifies, and more emphasis is placed on increased productivity and cost reduction, the development of a means to automatically monitor and assess the health of plant equipment becomes more important. This paper presents results of our research that integrates advances in the use of feature extraction, artificial neural networks, and communication/networking techniques for remote health assessment and failure diagnostics of laboratory and industrial rotating machinery. The key features of this effort are the ability to use internet for remote diagnostics, and combined Welch’s transformation and neural networks for signature creation and analysis.
Singular Value Decomposition of Road Events Into Characteristic Shapes
Authors: Ferris John B.
Published: November 2021

Road profiles are typically characterized by their spectral content. It has been noted by several researches, however, that road profiles are generally nonstationary signals that contain significant irregularities such as potholes. Such signals are not well described in the spectral domain. The objective of this work is to describe road profiles in the spatial domain by developing a set of characteristic shapes onto which individual events can be cast. A set of analytical functions describing these shapes is also developed.

In order to develop a set a characteristic shapes, more than a million events are investigated from a mixture of road types (from highways to gravel roads) and a variety of locations throughout the United States. A set of characteristic shapes is developed for each road type and location. Although the events were drawn from diverse samples, the resulting sets of characteristic shapes are nearly indistinguishable. This similarity allows a single set of characteristic shapes to describe events for a wide class of roads. Variations in these sets are discussed and used in deriving a set of orthogonal analytical functions that describe the characteristic shapes. Individual road events are then mapped onto this set of characteristic shapes. The implications of decomposing road events into these characteristic shapes are discussed.
A New Model of Improved Accuracy for the Dynamic Behavior of Spur Gears
Authors: Spitas Christos A. , Costopoulos Theodore N.
Published: November 2021

A new model of improved accuracy is proposed for the simulation of the dynamic behavior of a pair of spur gears that are free from manufacturing and mounting errors. The load-induced expansion of the actual path of contact with the occurrence of tooth edge contact is taken into account in order to better explain the tooth load sharing process near the lowest and highest point of single tooth contact (LPSTC, HPSTC). In addition, an accurate friction model is utilised and the effect of elastohydrodynamic lubricant film formation on gear vibration is taken into account. Simulation results are extracted for various operating speeds and an evaluation of the proposed model is conducted. The model is constructed in a modular fashion and can consequently be used as a building block for larger mechanisms, such as gear trains and multi-stage gearboxes.
The Influence Region Analysis for the Delayed Resonator Vibration Absorber
Authors: Grillo Giulio , Olgac Nejat
Published: November 2021

This paper presents an influence region analysis for an actively tuned vibration absorber, the Delayed Resonator (DR). DR is shown to respond to tonal excitations with time varying frequencies [1–3]. The vibration suppression is most effective at the point of attachment of the absorber to the primary structure. In this study we show that proper feedback control on the absorber can yield successful vibration suppression at points away from this point of attachment. The form and the size of such “influence region” strongly depend on the structural properties of the absorber and the primary system. There are a number of questions addressed in this paper:

a) Stability of vibration absorption, considering that a single absorber is used to suppress oscillations at different locations.

b) Possible common operating frequency intervals in which the suppression can be switched from one point on the structure to the others.

A three-degree-of-freedom system is taken for as example case. One single DR absorber is demonstrated to suppress the oscillations at one of the three masses at a given time. Instead of an “influence region” a set of “influence points” is introduced. An analysis method is presented to find the common frequency interval in which the DR absorber operates at all three influence points.
Optimization of the Sound Source Position for Shaping Acoustically-Structurally Coupled Cavities
Authors: Sorguc Arzu Gonenc , Hagiwara Ichiro , Shi Qinzhong , Akagunduz Haldun
Published: November 2021

In this study, sound field inside acoustically-structurally coupled rectangular cavity excited by structural loading and sound sources is shaped by optimizing the position of the sound source. In the optimization, Most Probable Optimal Design (MPOD) based on Holographic Neural Network is employed and the results are compared with Sequential Quadratic Programming (SQP). It is shown that source position, rather than source strength, is more effective in acoustically controlled modes. The nodal positions for in-vacuo acoustical normal modes are good candidates for initial starting points.
Motion Synchronization for Multi-Cylinder Electro-Hydraulic System
Authors: Sun Hong , Chiu George T.-C.
Published: November 2021

This paper presents a nonlinear control algorithm to address the motion synchronization problem for a multi-cylinder electro-hydraulic (EH) system. A 2-step design approach is applied such that it utilized linear MIMO robust control technique to design an outer loop motion synchronization controller. A nonlinear SISO perturbation observer based pressure/force controller is designed for each of the lift cylinder as the inner loop controller to handle the nonlinearities associated with the EH actuators. Experimental results on a 4-cylinder system are presented to verify the effectiveness of the proposed approach.
Gear Fatigue Crack Size Estimation Using Embedded Modeling
Authors: Li C. James , Lee Hyungdae , Choi Suk Hwan
Published: November 2021

This paper describes an embedded modeling methodology for identifying gear meshing stiffness from measured gear angular displacement or transmission error (which is the difference between where the gear tooth is physically and where it should be if the gear was perfect). An embedded model integrating a physical based model of the gearbox and a parametric representation, in the form of truncated Fourier series, of meshing stiffness is established. A solution method is then used to find the meshing stiffness that minimizes the discrepancy between model output and the measured output. Furthermore, an algorithm is also developed to estimate the size of tooth crack from identified meshing stiffness. Both simulation and experimental studies were conducted to evaluate if identified tooth meshing stiffness can reveal a tooth crack effectively, and if the crack size can be estimated with adequate level of accuracy.
Novelty Detection Using Auto-Associative Neural Network
Authors: Sohn Hoon , Worden Keith , Farrar Charles R.
Published: November 2021

The primary objective of novelty detection is to examine if a system significantly deviates from the initial baseline condition of the system. In reality, the system is often subject to changing environmental and operation conditions affecting its dynamic characteristics. Such variations include changes in loading, boundary conditions, temperature, and humidity. Most damage diagnosis techniques, however, generally neglect the effects of these changing ambient conditions. Here, a novelty detection technique is developed explicitly taking into account these natural variations of the system in order to minimize false positive indications of true system changes. Auto-associative neural networks are employed to discriminate system changes of interest such as structural deterioration and damage from the natural variations of the system.
Non-Disruptive Online Identification of Linearly Parametrized Systems
Authors: Tarraf Danielle C. , Asada H. Harry
Published: November 2021

The subject of this paper is online identification of systems described by linearly parametrized models, under the assumption that the parameters in question are slowly time varying, and with the requirement that the normal operation of the system is left completely undisturbed by the estimation procedure. A Lyapunov-based parameter estimator design for a class of LP systems is presented, assuming that we have no control over any of the system inputs, including control inputs. The estimation is guaranteed to converge provided good knowledge of extreme scenarios is available and provided certain observability-like requirements, derived in the paper, are met. The proposed design procedure is interpreted in the light of observer design for an ‘envelope’, augmented system where the parameters to be estimated are treated as slow state variables. Illustrative numerical examples follow; Good performance is observed both for the idealized case and for the case where sensor noise is present.
Adaptive Control for Nonlinear Matrix Second-Order Systems With Sign-Varying Damping and Stiffness Operators
Authors: Chellaboina VijaySekhar , Haddad Wassim M. , Hayakawa Tomohisa
Published: November 2021

A direct adaptive control framework for a class of nonlinear matrix second-order dynamical systems with state-dependent uncertainty is developed. The proposed framework guarantees global asymptotic stability of the closed-loop system states associated with the plant dynamics without requiring any knowledge of the system nonlinearities other than the assumption that they are continuous and lower bounded. Generalizations to the case where the system nonlinearities are unbounded are also considered. In the special case of matrix second-order systems with polynomial nonlinearities with unknown coefficients and unknown order, we provide a universal adaptive controller that guarantees closed-loop stability of the plant states.
Modeling and Analysis for Thermal Control of Spindles for Reconfigurable Machines
Authors: Stein Jeffrey L. , Harder John E.
Published: November 2021

Control of thermally induced bearing loads remains an important but unsolved problem for precision, high-speed, metal cutting, machining spindles. Spindle dynamic performance, as well as spindle life, depends on bearing loads. Because these loads can change drastically with a change in process conditions, poor spindle dynamic performance, and dramatically reduced bearing life can result. The purpose of this paper is to evaluate the feasibility of controlling bearing loads by controlling the heat generated by a thermal actuator placed around the housing of the spindle. A mathematical model of the open loop response of a laboratory prototype spindle is developed and validated. The model is then used to evaluate the closed loop performance.

The results show that closed loop control of the bearing load is achievable in steady state and under bandwidth limited transient conditions. The proposed system has reasonable command authority when additional heat is required, however, it is possible for the system to lose control when the heater is required to “provide” negative heat. This situation can be mitigated by proper choice of initial preload. As expected, measurement noise limits the control gain but is not a limiting factor. More open loop tests are suggested to validate the model under a broader set of conditions. In addition, closed loop validation is suggested. However, based on results obtained it appears bearing load control is achievable by controlling the thermal field around the spindle.
Input Profiling for Injection Molding by Reinforcement Learning
Authors: Wang Fan , Dong Shaoqiang , Danai Kourosh , Kazmer David O.
Published: November 2021

An adaptation method is investigated for improving the shape of input profiles in injection molding. The noted characteristic of injection molding is that performance feedback (i.e., part quality measure) becomes available only at the end of the cycle, therefore, the performance of the entire sequence of inputs that form the profile is evaluated by the same delayed measure at the end of the cycle. The proposed profiling method uses the concept of reinforcement learning, which is particularly suited to problems with delayed feedback. For an initial study, the method is tested in improving the profiles of the ram velocity and packing pressure. For this study, a simulation program is used to provide estimates of digital video disks (DVDs) quality attributes as feedback for evaluating the performance of the adapted profiles. The initial results indicate that the proposed method is effective in refining the profiles, which will lead to better quality parts with faster cycles.
Fault Diagnostic System Design Using LMIs, With Applications to Health Monitoring for GPS-Based Lateral Vehicle Control
Authors: Rajamani Rajesh , Shrivastava Ankur
Published: November 2021

This paper develops an explicit design methodology for development of observer-based sensor health monitoring systems using Linear Matrix Inequalities. The developed methodology applies to linear parameter-varying systems with three or more sensors in which the state is observable through any one of the sensors. A fault in any of the system sensors can be uniquely identified by the diagnostic system.

The developed methodology is applied to health monitoring of the lateral sensors on a GPS-controlled truck. A set of three sensors on the truck consisting of a GPS system, a lateral accelerometer and a yaw-rate gyroscope is considered. The performance of the fault diagnostic system is documented from extensive experimental results. Experimental results show that the fault diagnostic system can correctly detect a failure in any of the 3 sensors and accurately identify the source of the fault.
Robust Fault Classification and Handling for Longitudinal Vehicle Control
Authors: Song Bongsob , Howell Adam , Hedrick Karl
Published: November 2021

In this paper, a method of analyzing the performance loss caused by faults that effect the longitudinal control of an automated vehicle is presented. First, a hybrid longitudinal controller based on Dynamic Surface Control (DSC) is developed to provide robust stabilization. Then, ellipsoidal approximations of the tracking error bounds are obtained via convex optimization for the nonlinear closed-loop system. The bounds are then used to design a fault classification scheme and fault management system based on the amount of performance loss as measured by a quadratic Lyapunov function. Simulation results of the fault tolerant controller are shown for both single and multiple multiplicative faults.
Multi-Modal Diagnostics for Vehicle Fault Detection
Authors: Schwall Matthew L. , Gerdes J. Christian
Published: November 2021

On-board vehicle diagnostic systems must have low development and hardware costs in order to be viable. Model-based methods have shown promise since they use analytical redundancy to reduce costly physical redundancy. However, these methods must also be computationally efficient and function accurately even with simple, low-cost models.

The approach presented in this paper uses multiple simple models to analyze dissimilar observable modes of a system. Residuals generated using the models are related and interpreted in a Bayesian network to determine fault probabilities and yield a diagnosis. The technique is demonstrated with a diagnostic system for automobile handling.
Sway Suppression of Suspended Payloads With Hoisting Using Digital Filters
Authors: Economou D. , Antoniadis I.
Published: November 2021

A method is proposed for the suppression both of the transient as well as the residual sway of suspended payloads, including also cases where hoisting occurs during the payload transfer motion. The proposed method is based on the preconditioning of the inputs to the system by digital filtering the input function. Conventional FIR or IIR digital filters can be used for the preconditioning approach. The method is demonstrated in the case of a suspended load carried by a gantry crane. Extensive simulation results clearly verify the effectiveness of the approach.
Uncalibrated Vision-Based Control of Two-Wheeled Mobile Robots
Authors: Piepmeier Jenelle Armstrong , Morgan Peter A.
Published: November 2021

An quasi-Newton method with Jacobian estimation is used to control a mobile robot utilizing visual feedback. The method is uncalibrated, requiring no camera calibration or known robot kinematics. Given a proper task configuration, the robot can be controlled such that it follows a moving target. This paper investigates the appropriate task configurations that result in a controllable system.
Technologies in Surgical Robotics
Authors: Belligundu Sunil , Shiakolas Panayiotis S.
Published: November 2021

This paper presents a partial review of in-use, experimental or under development robotics technology applications in the medical field. The scope of the paper was narrowed by focusing on technologies related to surgical robotics, and applied to surgical procedures for Orthopedics, Telesurgery, Minimally Invasive Surgery, Endoscopy and Neurosurgery. Results of the review revealed that robotics in surgery are correctly considered as a tool for enhancing, not replacing the surgeon’s capabilities. Robotics technology is slowly but steadily gaining acceptance and usage in the field of surgery, but still faces many challenges. Rapid and continuous improvements in robotic technologies have great potential in advancing robotics use in the surgical field.
Integration of Smart Actuators in the Structure of Robots for High-Speed and Precision Object Manipulation
Authors: Rastegar Jahangir S. , Yuan Lifang
Published: November 2021

A systematic method is presented for optimal integration of smart actuators into the structure of robot manipulators for the purpose of enabling them to perform smooth object manipulation with smooth actuated joint motions. Here, the motions are considered to be smooth if they do not contain high harmonic components. For optimal positioning of smart actuators in the structure of robot manipulators, a method is developed based on the evaluation of the transmissibility of displacement (velocity and/or force) from the smart actuators to the robot manipulator joint motions and the end-effector displacements (velocity and/or force). A method is then presented for synthesizing actuated joint and object motions to achieve trajectories that do not contain high harmonic components. By minimizing the high harmonic components of the required joint and object motions with properly sized and placed smart actuators, such computer-controlled machines can operate at relatively higher speeds and achieve greater tracking precision with minimal vibration and control problems. A number of numerical examples are provided.
Sensor-Based Coverage for Demining: Exact Cellular Decompositions and Uncertain Detectors
Authors: Choset Howie , Acar Ercan U. , Zhang Yangang , Schervish Mark
Published: November 2021

Coverage path planning is the determination of a path that a robot must take in order to pass itself, a detector, or some other effector over each point in an environment. Applications include demining, floor scrubbing, and inspection. In previous work, we developed the boustrophedon cellular decomposition, an exact cellular decomposition approach, for the purposes of coverage. Each cell in the boustrophedon decomposition is covered with simple back and forth motions. Therefore, coverage is reduced to finding an exhaustive path through a graph that represents the adjacency relationships of the cells in the boustrophedon decomposition. Such a path will ensure that a detector passes over all points in the environment, but it does not guarantee that all ordnance is indeed detected because mine detectors have error. Therefore, we also consider probabilistic methods to determine paths for the robot to maximize the likelihood of detecting all ordnance in a target location using a priori known information.
Direct Numerical Simulation of Drops in Three Dimensional Viscoelastic Simple Shear Flows
Authors: Pillapakkam Shriram B. , Singh Pushpendra
Published: November 2021

A three dimensional finite element scheme for Direct Numerical Simulation (DNS) of viscoelastic two phase flows is implemented. The scheme uses the Level Set Method to track the interface and the Marchuk-Yanenko operator splitting technique to decouple the difficulties associated with the governing equations. Using this numerical scheme, the shape of Newtonian drops in a simple shear flow of viscoelastic fluid and vice versa are analyzed as a function of Capillary number, Deborah number and polymer concentration. The viscoelastic fluid is modeled via the Oldroyd-B model. The role of viscoelastic stresses in deformation of a drop subjected to simple shear flow and its effect on the steady state shape is analyzed. Our results compare favorably with existing experimental data and also help in understanding the role of viscoelastic stresses in drop deformation.
Experimental Visualization of Lagrangian Coherent Structures in Aperiodic Free Surface Flow
Authors: Chrisohoides Antonis , Sotiropoulos Fotis
Published: November 2021

We propose a simple experimental technique for visualizing Lagrangian coherent structures (LCS) in turbulent free-surface flows. The technique employs digital photography to record the transport of passive tracers (small paper pieces) introduced manually at the free surface. Coherent eddies are detected by time-averaging the instantaneous light intensity fields on finite-size temporal windows. We demonstrate the potential of the method by applying it to visualize the flow in the vicinity of a surface-piercing rectangular block mounted at one corner of a rectangular open channel. We show that by appropriately selecting the time averaging window, the technique can reveal the presence of organized patterns in the chaotic instantaneous flow and elucidate their complex interactions.
Calculation of Transient Flow in Circulating Fluidized Beds With Straight and Double Abrupt Outlet Configuration: Relation With the Inelasticity of the Particle-Particle Collisions
Authors: De Wilde Juray , Vierendeels Jan , Heynderickx Geraldine J. , Dick Erik , Marin Guy B.
Published: November 2021

Gas-solid flow in industrial scale Circulating Fluidized Beds (CFB’s) is calculated in 3D using the Eulerian-Eulerian approach and the Kinetic Theory of Granular Flow (KTGF). Two outlet configurations are used: a straight top outlet and a double abrupt T-outlet. The effect of the value of the restitution coefficient for particle-particle collisions on the stability of the flow is investigated. Oscillations appearing in CFB’s, are shown to be gravity waves.
An E/H Displacement and Power Control Design for Hydraulic Variable Displacement Pumps
Authors: Du Hongliu
Published: November 2021

In this paper, a novel E/H control design is proposed for displacement and power control of hydraulic variable displacement pumps. The displacement control is treated as tracking the desired swashplate angle time history αd(t) with the consideration of system uncertainties. The robust stability of the control system is achieved by a very rugged control design. The resulting error dynamics is of first order, which guarantees no overshoot for step response. An adaptive term is added to further improve the system performance. The smooth transfers between the displacement control and power control modes are achieved. The provided control design significantly simplifies the hydro-mechanical design for variable displacement pumps and results in a cost reduced pump with a better performance. Experimental results validate the theoretical development.
Investigation of the Ageing Behaviour of Ecologically Acceptable Hydraulic Fluids and Their Interaction With Surface Coatings
Authors: Murrenhoff Hubertus , Schmidt Martin
Published: November 2021

Environmental aspects have a major impact on the application of technical products and decide about their success. Especially, with regard to hydraulic systems, these aspects can be fulfilled by the use of environmentally friendly fluids, based on synthetic esters. But the fluid’s properties strongly differ from the ones of the well-known mineral oil based fluids. Therefore, a profound knowledge of the fluid’s properties and their interaction with hydraulic components is essential for a successful usage of these fluids in hydraulic systems and moreover the basis of the development of a new generation of fluids which is going to take place within a research program at the University of Aachen. There, new environmentally friendly fluids are developed and tested in tribosystems applying new surface coated materials. Aim is to transfer important tribological features from fluids onto these base materials. Taking this route certain additives are no longer required and the missing characteristics have to be taken on by specially coated materials.

Therefore, analysis of the properties of synthetic esters, their change due to usage and the interaction with specially coated materials have been carried out. Moreover, a test facility will be presented which is able to do both ageing the fluid to analyze its ageing behavior and testing the fluid’s tribological properties. Besides the presentation of results with respect to the subject ageing of esters also results with respect to the influence of ageing on the tribological fluid properties will be shown.
Production of Diffusion Flames in the Near Extinction Limit Regime Using a Hele-Shaw Apparatus in a Simulated Low Gravity Environment
Authors: Oravecz-Simpkins Lisa M. , Wichman Indrek S.
Published: November 2021

A Hele-Shaw apparatus that produced spreading diffusion flames in the near extinction limit was designed and constructed. A scaling analysis was used to determine the maximum test section height for which effects of gravity could be neglected. Preliminary results showed that this apparatus could be used to produce flame instabilities which resemble drop tower test results from NASA [1,2] and other diffusion flame instability studies [3,4,5,6]. Therefore, the Hele-Shaw apparatus is useful for studying flames in a simulated low gravity environment. Additional unstable behaviors seen in the device, such as flame pulsing and spreading blue cusps, not in the NASA testing further supported the need for investigations during longer microgravity times on the International Space Station. The initial testing was only used to gain an observable region of unstable flames. Further studies will be directed at explaining and quantifying specific behaviors with test conditions.
A New LES Pool Fire Simulation Tool
Authors: Rawat Rajesh , Spinti Jennifer P. , Yee Wing , Smith Philip J.
Published: November 2021

In a large-scale pool fire simulation, the processes that must be modeled are complex and coupled. The flow is often highly turbulent, dynamic vortical structures are present, the chemical reactions involve several thousand elementary steps and hundreds of species/intermediates, and radiation, the dominant mode of heat transfer, is strongly affected by the presence of soot. The range of length and time scales associated with all these processes cannot be simulated on even the most powerful supercomputers available today. Our approach to making this intractable problem tractable has been twofold: one, to improve the models used at all levels in the simulation (i.e., transport models and subgrid scale models) and two, to parallelize the simulation tool to run on massively parallel machines. We have employed Large Eddy Simulation (LES) to model the fluid dynamics and the convection-diffusion scalar transport. LES successfully captures the transient nature of the coherent vortical structures present in a pool fire. We have integrated these improved models into a computational framework that provides support for parallelization. Preliminary validation results show the capability of the fire simulation tool to capture the puffing nature of pool fires. In addition, scalability studies of the simulation tool reveal close to linear scalability up to 500 processors.