Static Engine Research Articles

Impact of Device Trajectory and Device Type on Compression During Simulated Bone Resorption in a Subtalar Model

Introduction/Purpose: Despite the prevalence of subtalar arthrodesis, certain risk factors (smoking, diabetes) diminish fusion outcomes and are associated with decreased bone healing, leading to increased duration of high stresses at the bone/device interface, ultimately leading to loosening/loss of compression. Existing fixation devices using static engineering materials (i.e., titanium) falter when postoperative bone resorption/joint-settling occurs, justifying improved fixation devices that drive continuous compression in the setting of bone resorption. Devices that leverage superelastic properties of NiTiNOL can provide sustained dynamic compression in the setting of bone resorption, ideally positioning them for these patient populations. Thus, the goal of this study was to characterize the biomechanical response of static and dynamic (NiTiNOL) devices across multiple trajectories in subtalar arthrodesis in the setting of simulated bone resorption. Methods: Compressive forces between synthetic talus and synthetic calcaneus (Sawbones) were measured for two commercially available orthopedic fixation devices (Dynamic = 7.0mm dia. 90mm length, Static = 7.0mm dia; 90mm length, N =6/group) in a custom subtalar fixture. The devices were inserted according to manufacturer instructions (FigA) while maintaining a gap between bone segments using a removable spacer. Two devices were inserted within each group (Dynamic, Static, Static+Dynamic) in either a parallel or diverging trajectory (FigA). Following insertion of devices, the spacer was removed enabling measurement of initial compression (Transducer Techniques). Subsequently, the bones were allowed to move into apposition while continued measurements of compression were collected, enabling determination of resorption capacity (distance) prior to loss of compressive force. Data were analyzed using a two-way ANOVA with Tukey post hoc test (α=.05). Results: The Dynamic group exhibited significantly increased initial load as compared to the Static and Static + Dynamic groups in both the parallel and diverging trajectories (FigB, p=.031). The initial load provided by the first device in the Dynamic group was significantly increased as compared to the Static group (FigB, p=.030). The Dynamic group exhibited a significant increase in initial load upon insertion of the second device (FigB, p Conclusion: Generating and maintaining sufficient compression is requisite for successful subtalar arthrodesis outcomes, especially in the presence of bone resorption. These data illustrate the significant increase in both initial load and resorption capacity of the sustained dynamic compression device (Dynamic) as compared to the Static and Static + Dynamic groups. The addition of a second Dynamic device markedly increased the compression, whereas the use of static devices prevented generation of increased compressive forces. Device trajectory did not significantly impact the arthrodesis construct biomechanical performance. One dynamic screw has better biomechanical performance than two static screws. Figure A) Illustration of guide wire placements prior to device insertion. B) Initial load generated between boney segments. C) Resorption distance prior to loss of compression.

Prediction of the fuel regression-rate in a HDPE single port hybrid rocket fed by liquid nitrous oxide

This paper presents a computational thermo-fluid-dynamic model of the hybrid rocket internal ballistics, which was developed with the specific aim of predicting the axial position and severity of the increased fuel-consumption spots observed in static engine firings. Numerical simulations of the internal flow field have been carried out on the configuration of the engine previously fired. The novelty of this work consists in providing a simplified methodology to calculate the regression rate measured burning liquid nitrous oxide with high-density polyethylene, which involves a series of additional complexities with respect to the case of pure gaseous oxygen (i.e., a non-decomposing oxidizer). Indeed, the typical non-premixed flame developed in the chamber is preceded by a decomposition reaction of the nitrous oxide, whose simulation implies further numerical cost. For the validation of the model, data retrieved from two firing tests are compared with the numerical results revealing good agreement of both the average regression rate and fuel consumption axial profile. A dedicated study was performed to assess the reliability of the assumptions underlying the model. Results are also compared with those obtained with either pure oxygen or 85 wt.% hydrogen peroxide. Finally, a different prechamber arrangement was suggested to address the issue deriving from excessive fuel regression.

Resistive Multi-Gas Sensor for Simultaneously Measuring the Oxygen Stoichiometry (λ) and the NOx Concentration in Exhausts: Engine Tests under Dynamic Conditions.

Due to increasingly stringent limits for NOx emissions, there is now more interest than ever in cost-effective, precise, and durable exhaust gas sensor technology for combustion processes. This study presents a novel multi-gas sensor with resistive sensing principles for the determination of oxygen stoichiometry and NOx concentration in the exhaust gas of a diesel engine (OM 651). A screen-printed porous KMnO4/La-Al2O3 film is used as the NOx sensitive film, while a dense ceramic BFAT (BaFe0.74Ta0.25Al0.01O3-δ) film prepared by the PAD method is used for λ-measurement in real exhaust gas. The latter is also used to correct the O2 cross-sensitivity of the NOx sensitive film. This study presents results under dynamic conditions during an NEDC (new European driving cycle) based on a prior characterization of the sensor films in an isolated sensor chamber with static engine operation. The low-cost sensor is analyzed in a wide operation field and its potential for real exhaust gas applications is evaluated. The results are promising and, all in all, comparable with established, but usually more expensive, exhaust gas sensors.

Effects of adverse sea conditions on propulsion and manoeuvring performance of low-powered ocean-going cargo ship

Current EEDI (Energy Efficiency Design Index) regulations striving to reduce the installed engine power on new ships for a low EEDI may lead to underpowered ships having insufficient power when operating in adverse sea conditions. In this paper, the operational safety of a low-powered ocean-going cargo ship operating in adverse sea conditions has been investigated using an integrated ship propulsion, manoeuvring and sea state model. The ship propulsion and manoeuvring performance, especially the dynamic engine behaviour, when the ship is sailing in heavy weather and turning into head sea, have been studied. According to the results, the dynamic engine behaviour should be considered when assessing the ship operational safety, as the static engine operating envelope is inadequate for the safety assessment. The impact of PTO/PTI (power-take-off/in) operation and changing propeller pitch on the ship thrust availability in adverse sea conditions have also been investigated. To protect the engine from mechanical and thermal overloading, compressor surge and over-speeding during dynamic ship operations and/or in high sea states, the engine and propeller should be carefully controlled. The paper shows that if in (heavy) adverse weather the propeller pitch can be reduced or if the shaft generator can work as a motor (PTI), more thrust can be developed which can significantly improve the operational safety of the ship.

Mean value first principle engine model for predicting dynamic behaviour of two-stroke marine diesel engine in various ship propulsion operations

Analysis of ship propulsion system performance is often performed using detailed hydrodynamic models to assess load changes, which are subsequently compared to static engine limits, or by detailed engine models that are rarely integrated with sufficiently detailed propulsion models for load change estimation. To investigate the dynamic engine (overloading) behaviour and ship propulsion performance under various heavy operating conditions, a Mean Value First Principle Parametric (MVFPP) engine model is integrated into a ship propulsion system model in this paper. An upgraded thermodynamic-based MVFPP model for two-stroke marine diesel engines is presented, in particular a newly developed MVFPP gas exchange model. Based on the integrated propulsion system model of a benchmark ocean-going chemical tanker, the engine dynamic behaviour during ship acceleration, deceleration and crash stop has been investigated. Results show that, during dynamic processes, the engine could be thermally overloaded even if the engine power trajectory is inside the static engine operating envelope. The paper contributes to finding proper indicators for thermal overloading of modern two-stroke marine diesel engines. It is demonstrated that when matching the engine with the propeller and designing the ship propulsion control system, not only the static engine operating envelope, but also the dynamic engine behaviour should be considered. • Mean Value First Principle Parametric (MVFPP) model for 2-stroke marine diesel engine. • Novel approach to two-zone modelling of scavenging process. • MVFPP model is balanced choice to predict engine behavior in drive system simulation. • Static performance maps & limits inadequate for prediction of engine dynamic behavior. • MVFPP model can provide deeper understanding of thermal overloading of engines.

Research on Dynamics Stiffness of Honeycomb Sandwich Structure Door

During the emergency opening of the aircraft door in the air, the door must experience a complex and harsh mechanical environment. In order to ensure the high reliability of the door, it must have sufficient dynamic stiffness. When using finite element software for static engineering analysis, the calculation results often have large deviations due to improper simplification of the motion links in the structure. Aiming at the characteristics of the honeycomb sandwich structure of a class of civil aircraft doors, a combination of topology optimization and dynamic analysis was adopted to take into account the door load and the door opening speed. The results of dynamic calculation show that when the door is opened in the air, the bending deformation during cruise is in compliance with the requirements, and the structural rigidity meets the functional requirements. The research results have important effects on the design and optimization of the stiffness performance of honeycomb sandwich doors.

Variability analysis of ABS solid fuel manufactured by fused deposition modeling for hybrid rocket motors

The process of fused deposition material (FDM) was used to manufacture propellant grains of Acrylonitrile Butadiene Styrene (ABS) as novel rocket fuel grain, with three types of geometry in the burning port. These solid fuel grains were used to measure the typical characteristics of combustion in rocket motors such as thrust and pressure inside the combustion chamber, seeking to obtain preliminary characteristics of operation and analyze the effect of combustion port geometry on pressure and thrust, using Multivariate Analysis of Variance (MANOVA) as statistical method. Two of the three geometries were manufactured with a helical-finocyl configuration, specially designed to be fabricated by Direct Digital Manufacturing (DDM), the other one was a straight-bore geometry also by DDM. This characterization experiment was performed on a static hybrid rocket engine, designed to inject 99.98% pure nitrous oxide into a combustion chamber with capacity to withstand 6.9 MPa of pressure, with an easy-to-exchange nozzle, avoiding erosive behavior in the throat. Statistical analyses made with the ABS fuel grains, suggest a significant effect on rocket motor pressure and thrust, due to helical geometric changes made to the combustion port of solid fuel grains made by FDM manufacture process.

Site-directed mutagenesis of the quorum-sensing transcriptional regulator SinR affects\xa0the biosynthesis of menaquinone in\xa0Bacillus subtilis

BackgroundMenaquinone (MK-7) is a highly valuable vitamin K2 produced by Bacillus subtilis. Common static metabolic engineering approaches for promoting the production of MK-7 have been studied previously. However, these approaches caused an accumulation of toxic substances and reduced product yield. Hence, dynamic regulation by the quorum sensing (QS) system is a promising method for achieving a balance between product synthesis and cell growth.ResultsIn this study, the QS transcriptional regulator SinR, which plays a significant role in biofilm formation and MK production simultaneously, was selected, and its site-directed mutants were constructed. Among these mutants, sinR knock out strain (KO-SinR) increased the biofilm biomass by 2.8-fold compared to the wild-type. SinRquad maximized the yield of MK-7 (102.56 ± 2.84 mg/L). To decipher the mechanism of how this mutant regulates MK-7 synthesis and to find additional potential regulators that enhance MK-7 synthesis, RNA-seq was used to analyze expression changes in the QS system, biofilm formation, and MK-7 synthesis pathway. The results showed that the expressions of tapA, tasA and epsE were up-regulated 9.79-, 0.95-, and 4.42-fold, respectively. Therefore, SinRquad formed more wrinkly and smoother biofilms than BS168. The upregulated expressions of glpF, glpk, and glpD in this biofilm morphology facilitated the flow of glycerol through the biofilm. In addition, NADH dehydrogenases especially sdhA, sdhB, sdhC and glpD, increased 1.01-, 3.93-, 1.87-, and 1.11-fold, respectively. The increased expression levels of NADH dehydrogenases indicated that more electrons were produced for the electron transport system. Electrical hyperpolarization stimulated the synthesis of the electron transport chain components, such as cytochrome c and MK, to ensure the efficiency of electron transfer. Wrinkly and smooth biofilms formed a network of interconnected channels with a low resistance to liquid flow, which was beneficial for the uptake of glycerol, and facilitated the metabolic flux of four modules of the MK-7 synthesis pathway.ConclusionsIn this study, we report for the first time that SinRquad has significant effects on MK-7 synthesis by forming wrinkly and smooth biofilms, upregulating the expression level of most NADH dehydrogenases, and providing higher membrane potential to stimulate the accumulation of the components in the electron transport system.

Nonlocal integral static problems of nanobeams resting on an elastic foundation

Eringen’s nonlocal theory has been widely used for the study of micro- and nano-structures exhibiting size effect phenomena. Eringen’s nonlocal differential constitutive equation has been employed to structural engineering applications, and a number of inconsistencies and paradoxes has been raised. This work centers on exploring static engineering benchmark problems of a nanobeam resting on a Pasternak-type elastic foundation by means of the nonlocal integral elasticity for the first time. The modified kernel’s model and the two phase stress model leading to well-posed problems are used. The static responses of the integral models show to have a flexible behavior in comparison with those of the classic and the nonlocal differential models for all the investigated problems. Neither paradoxes nor inconsistencies are raised for the integral models. The modified kernel highlights the model’s robustness from a physical point of view. The conclusions are promising to spur the applications of nanomaterials, nanocomposites and biomaterials.

Dynamic Control of 4-Hydroxyisoleucine Biosynthesis by Modified l-Isoleucine Biosensor in Recombinant Corynebacterium glutamicum.

4-Hydroxyisoleucine (4-HIL), a promising drug for treating diabetes, can be synthesized from the self-produced l-isoleucine (Ile) by expressing the Ile dioxygenase gene ido in Corynebacterium glutamicum. However, the requirement of three substrates, Ile, α-ketoglutarate (α-KG), and O2, makes such de novo biosynthesis difficult to be fulfilled effectively under static engineering conditions. In this study, dynamic control of 4-HIL biosynthesis by the Ile biosensor Lrp-PbrnFE was researched. The native PbrnFE promoter of natural Ile biosensor was still weak even under Ile induction. Through tetA dual genetic selection, several modified stronger PbrnFEN promoters were obtained from the synthetic library of the Ile biosensor. Dynamic regulation of ido expression by modified Ile biosensors increased the 4-HIL titer from 24.7 mM to 28.9-74.4 mM. The best strain ST04 produced even a little more 4-HIL than the static strain SN02 overexpressing ido by the strong PtacM promoter (69.7 mM). Further dynamic modulation of α-KG supply in ST04 by expressing different PbrnFEN-controlled odhI decreased the 4-HIL production but increased the l-glutamate or Ile accumulation. However, synergistic modulation of α-KG supply and O2 supply in ST04 by different combinations of PbrnFEN-odhI and PbrnFEN-vgb improved the 4-HIL production significantly, and the highest titer (135.3 mM) was obtained in ST17 strain regulating all the three genes by PbrnFE7. This titer was higher than those of all the static metabolic engineered C. glutamicum strains ever constructed. Therefore, dynamic regulation by modified Ile biosensor is a predominant strategy for enhancing 4-HIL de novo biosynthesis in C. glutamicum.

Developing an endogenous quorum-sensing based CRISPRi circuit for autonomous and tunable dynamic regulation of multiple targets in Streptomyces

Quorum-sensing (QS) mediated dynamic regulation has emerged as an effective strategy for optimizing product titers in microbes. However, these QS-based circuits are often created on heterologous systems and require careful tuning via a tedious testing/optimization process. This hampers their application in industrial microbes. Here, we design a novel QS circuit by directly integrating an endogenous QS system with CRISPRi (named EQCi) in the industrial rapamycin-producing strain Streptomyces rapamycinicus. EQCi combines the advantages of both the QS system and CRISPRi to enable tunable, autonomous, and dynamic regulation of multiple targets simultaneously. Using EQCi, we separately downregulate three key nodes in essential pathways to divert metabolic flux towards rapamycin biosynthesis and significantly increase its titers. Further application of EQCi to simultaneously regulate these three key nodes with fine-tuned repression strength boosts the rapamycin titer by ∼660%, achieving the highest reported titer (1836 ± 191 mg/l). Notably, compared to static engineering strategies, which result in growth arrest and suboptimal rapamycin titers, EQCi-based regulation substantially promotes rapamycin titers without affecting cell growth, indicating that it can achieve a trade-off between essential pathways and product synthesis. Collectively, this study provides a convenient and effective strategy for strain improvement and shows potential for application in other industrial microorganisms.

A comparative study on in-flight modal identification of an aircraft using time- and frequency-domain techniques

In this study, in-flight modal identification analyses are made based on vibration data collected during a flight test of an aircraft, by using two different output-only identification techniques: frequency domain decomposition and data-driven stochastic subspace identification. The purpose of this study was to evaluate and compare the efficacy of the two methods in modal parameter estimation and to validate their capability in dealing with some challenging tasks such as time tracking of modal parameters and estimating modal damping ratios. In addition, the effects of different environmental conditions and maneuvers are investigated by separating the flight-test data, such as static engine start, taxi, takeoff, cruise, roll, climb, descend, and yaw maneuvers. It is demonstrated that the selection of operational conditions and maneuvers plays a crucial role in identifying the modal parameters of the aircraft.

Static internal combustion engine operating states in vehicle driving tests

The article presents the compression-ignition engine test results of static operating states in driving tests: NEDC (New European Driving Cycle), RDE (Real Driving Emissions) and the Malta custom test cycle, developed at the Poznan University of Technology. The NEDC and Malta tests were carried out as drive cycle simulations on the engine test bench, the RDE test was carried out in the real driving conditions. The engine operating states are described by the physical quantities of speed and torque. For each of the tests, zero- -dimensional characteristics of the values describing the engine operation states were determined, including: mean value and average standard deviation and coefficient of variation. Histograms of quantities describing the engines operating states for considered tests and driving conditions were also determined. A large diversity of zero-dimensional characteristics of the quantities describing the engines operating states for the considered driving tests and driving conditions was found.

INRFlow: An interconnection networks research flow-level simulation framework

This paper presents INRFlow, a mature, frugal, flow-level simulation framework for modelling large-scale networks and computing systems. INRFlow is designed to carry out performance-related studies of interconnection networks for both high performance computing systems and datacentres. It features a completely modular design in which adding new topologies, routings or traffic models requires minimum effort. Moreover, INRFlow includes two different simulation engines: a static engine that is able to scale to tens of millions of nodes and a dynamic one that captures temporal and causal relationships to provide more realistic simulations. We will describe the main aspects of the simulator, including system models, traffic models and the large variety of topologies and routings implemented so far. We conclude the paper with a case study that analyses the scalability of several typical topologies. INRFlow has been used to conduct a variety of studies including evaluation of novel topologies and routings (both in the context of graph theory and optimization), analysis of storage and bandwidth allocation strategies and understanding of interferences between application and storage traffic.

Initial assessment of the course of combustion process in a diesel engine powered by diesel oil and Brown’s gas

Application of water electrolyzer generating Brown’s gas as an additional source of supplying diesel engine was assessed in this article. Water, due to its slight conductivity must have been enriched with appropriate hydroxides. By-product of combustion of Brown’s gas is water vapour. Laboratory site consisted of: hydrogen generator, diesel engine 1,3 Multijet and apparatus for assessment of combustion process. The course of selected parameters of process of functioning of diesel engine of a vehicle with double supply – diesel oil and Brown’s gas. Empirical research were conducted in the conditions of static engine work. AVL – Indi Micro 602 was applied to indicate the engine. Selected parameters of combustion process were analysed. If application of the electrolzyer will be justified, the works on analysis of its energy balance and its control will be continued.

Why Are Clovis Fluted Points More Resilient than Non‐Fluted Lanceolate Points? A Quantitative Assessment of Breakage Patterns Between Experimental Models

For decades, archaeologists have wondered whether the Clovis Palaeoindian (c.11 600–10 800 radiocarbon yearsbp) practice of ‘fluting’, a flake removal technique that creates a distinctive shallow channel extending from the base of the projectile point towards the tip, bestowed a functional advantage over non‐fluted projectile points. Using analytical modelling and static engineering experiments, Thomaset al. (2017) found that points that more effectively redistribute stress and relocate damage can absorb significantly more energy, last longer and remain intact relative to points that do not experience these phenomena. In general, stress redistribution and damage relocation is significantly more likely to occur in fluted points, as opposed to non‐fluted points, suggesting that fluting acts as a ‘shock absorber’. Here, we present a comparative quantitative assessment of breakage patterns between Thomaset al.’s (2017) experimental points that shows those experiencing stress redistribution and damage relocation were also able to significantly better resist breakage, and to incur non‐catastrophic breaks, than points that less effectively redistribute stress and relocate damage. This more beneficial breakage pattern explains the material advantages provided by stress redistribution and damage relocation, and hence the potential motivation for fluting. This does not preclude the possibility that the process of fluting was accorded significance beyond its possible utilitarian value. Additional tests will be necessary to further resolve the ‘shock‐absorbing’ capabilities of fluting.

Progress in prediction of jet noise and quantification of aircraft/engine noise components

The bypass ratio of newer turbofan engines has been increasing steadily and has reached ∼10; even higher bypass ratios are being considered for improving aircraft fuel efficiency. An accurate method for the prediction of jet noise over a wide range of bypass ratio, from ∼5 to ultra-high bypass ratios (∼20), is required to address current and future needs. The main objective of the current study is the development of a procedure for real-world application that would permit the accurate prediction of jet noise, which in turn would enable the quantification of the non-jet noise component. A new empirical method for prediction of noise from realistic dual-stream jets is developed and validated against an extensive database acquired at model scale; the range of validity covers a velocity ratio ( Vs/Vp) ≥ ∼0.6, as this is the range of interest in real turbofan engines. Accurate absolute spectral predictions at all angles and all cycle conditions are first demonstrated at model scale. The same method is then extended to full-scale predictions, both from static engine tests and airplane flyover tests. The range of Strouhal number of interest in full-scale tests spans ∼0.1 to ∼100. Nearfield effects on the jet noise from dual-stream jets have been quantified and a simple and improved procedure for incorporating spectral effects has been developed. Accurate spectral predictions are obtained for noise from static engine tests and flyover tests, over a wide range of engine operating conditions and bypass ratio. Therefore, the good quality and accuracy of the new prediction method have been confirmed at both model scale and full scale, with and without forward flight. An absolute prediction takes ∼1 s on a workstation, as only a single scaling equation is utilized. The application of the new prediction method in gaining better quantification and understanding of the non-jet noise components, and their reduction, is described.

Комбинирование динамического символьного исполнения, статического анализа кода и фаззинга

This paper describes a new approach for dynamic code analysis. It combines dynamic symbolic execution and static code analysis with fuzzing to increase efficiency of each component. During fuzzing we recover indirect function calls and pass that information to the static analysis engine. This improves static path detection in the control flow graph of a program. Detected paths are used in dynamic symbolic execution to construct inputs which will cover new paths during execution. These inputs are used by the fuzzing tool to improve test-case generation and increase code coverage. The proposed approach can be used for classic fuzzing when the main goal is achieving high code coverage. As well it can be used for targeted analysis of paths and code fragments in the program. In this case the fuzzing tool accepts a set of programs addresses with potential defects and passes them to the static analysis engine. The engine constructs all paths connecting program entry point to the given addresses. Finally, dynamic symbolic execution is used to construct the set of inputs, which will cover these paths. Experimental results have shown that the proposed method can effectively detect different program defects.

Protecting Android Applications with Multiple DEX Files against Static Reverse Engineering Attacks

Protecting Android Applications with Multiple DEX Files against Static Reverse Engineering Attacks

Enterprise firewall virtualization design

Grid computing could consists of thousand of computers across the world with the role as the resource provider or Grid users. This conditions make a challenge for engineer to keep the Grid secure but at the same the Grid must be easily joined by clients and providers. This paper aims to propose a method to control enterprise firewall which is basically a static engine to be a dynamic engine to cope with the Grid needs. At the end of the paper, the results shows that this method is works and was tested using a real enterprise firewall.