Integrated Engineering System Research Articles

Microfluidic Droplet-Assisted Fabrication of Vessel-Supported Tumors for Preclinical Drug Discovery.

High-fidelity in vitro tumor models are important for preclinical drug discovery processes. Currently, the most commonly used model for in vitro drug testing remains the two-dimensional (2D) cell monolayer. However, the natural in vivo tumor microenvironment (TME) consists of extracellular matrix (ECM), supporting stromal cells and vasculature. They not only participate in the progression of tumors but also hinder drug delivery and effectiveness on tumor cells. Here, we report an integrated engineering system to generate vessel-supported tumors for preclinical drug screening. First, gelatin-methacryloyl (GelMA) hydrogel was selected to mimic tumor extracellular matrix (ECM). HCT-116 tumor cells were encapsulated into individual micro-GelMA beads with microfluidic droplet technique to mimic tumor-ECM interactions in vitro. Then, normal human lung fibroblasts were mingled with tumor cells to imitate the tumor-stromal interaction. The tumor cells and fibroblasts reconstituted in the individual GelMA microbead and formed a biomimetic heterotypic tumor model with a core-shell structure. Next, the cell-laden beads were consociated into a functional on-chip vessel network platform to restore the tumor-tumor microenvironment (TME) interaction. Afterward, the anticancer drug paclitaxel was tested on the individual and vessel-supported tumor models. It was demonstrated that the blood vessel-associated TME conferred significant additional drug resistance in the drug screening experiment. The reported system is expected to enable the large-scale fabrication of vessel-supported heterotypic tumor models of various cellular compositions. It is believed to be promising for the large-scale fabrication of biomimetic in vitro tumor models and may be valuable for improving the efficiency of preclinical drug discovery processes.

Thermoelectric Generation From Exhaust Heat in Electrified Natural Gas Trucks: Modeling and Analysis of an Integrated Engine System Performance Improvement

AbstractUsing thermoelectric generators (TEG) to reduce exhaust heat loss from internal combustion engines can improve emissions and the fuel economy of conventional and electrified vehicles. However, TEG potentials have not been investigated in hybridized, compressed natural gas (CNG), twin-turbocharged, and spark-ignited (SI) engines. This work demonstrates TEG's effectiveness in boosting a hybridized 3.0 L CNG engine using model-based development. TEG experiments are performed to measure thermal performances under different inlet gas conditions for model validations. Simplified user-defined functions of flow friction and heat transfer coefficients are used to calibrate the model. A fast-calibration model can reproduce measured heat transfer, pressure drop, and thermal performances. The engine performances are validated against measured 35 steady-state conditions from the production engine used in light-duty CNG trucks under the JE05 drive cycle. Next, the model is connected to the turbocharging system downstream of the well-calibrated four-cylinder SI engine model. Under the peak performance condition (peak brake thermal efficiency BTE at 2400 RPM and 102 kW load), the results show that the engine BTE is improved by 0.56% using a 7 × 9 TEG module arrangement (three-sheet TEG with 1.5× A4 size). A 9 × 10 arrangement can enhance the BTE to 0.8%. Effective electrical power is generated up to 1.168 kW from the TEG, depending on the JE05 operating regions, without significant brake power loss.

Terahertz Waves Enhance the Permeability of Sodium Channels

With the help of molecular dynamics simulations and an artificial sodium channel model, we corroborated that the application of terahertz stimulation at a characteristic frequency can largely increase the permeability of the sodium channel by a factor of 33.6. The mechanism is that the carboxylate groups in the filter region transfer the absorbed terahertz photon energy to the sodium ions, which increase the ions’ kinetic energy; this results in breaking the hydrated hydrogen bonding network between the hydrosphere layer of the ions and the carboxylate groups, thereby increasing their diffusion and reducing the energy barrier for them to cross the channel. This study on terahertz-driven particle transmembrane transport offers new ideas for targeted therapy of channel diseases and for developing novel integrated engineering systems in energy conversion and storage.

Efficiency, economic and environmental impact assessments of a new integrated rail engine system using hydrogen and other sustainable fuel blends

Locomotives still use antiquated engines, such as internal combustion engines operated by fossil fuels which cause global warming due to their significant emissions. This paper investigates a new hybridized locomotive engine containing a gas turbine system, solid oxide fuel cell system, heat recovery system, and an on-board hydrogen production system. This new integrated engine is operated using five fuel blends composed of alternative fuels, such as hydrogen, methane, methanol, ethanol and dimethyl ether. The current investigation involves multiple studies, such as exergy analysis, exergoeconomic analysis and exergoenvironmental analysis to assess the integrated engine system from three perspectives: efficiency/irreversibility, cost and environmental impact. The present study results show that the net power of this new engine is 4948.6 kW, and it has an exergetic efficiency of 62.7% according to the fuel-product principle. In addition, this engine weighs about 9 tons and costs about $10.2 M, with a levelized cost rate of 147 $/h and 14.06 mPt/h of overall component-related environmental impact rate. The average overall specific fuel and product exergy costs are about 37 $/GJ and 60 $/GJ, and the minimum values are 13.3 $/GJ and 21.8 $/GJ using the methane and hydrogen blend, respectively. Also, the average overall specific fuel-product exergoenvironmental impacts are about 15 and 23 mPt/MJ, respectively. Furthermore, the on-board hydrogen production has an average exergy cost of 274 $/GJ with an environmental impact of 52 mPt/MJ. Moreover, the hydrogen blended with methane or methanol is found to be more economical with less environmental impact.

Pretreatment processes assisted subcritical water hydrolysis for valorisation of spent coffee grounds

SummaryThis study investigated the effect of sequential extraction techniques and pretreatment methods in enhancing the recovery of high‐value products from spent coffee ground. Supercritical carbon dioxide (SC‐CO2) deoiling was performed to recover non‐polar lipids, and subcritical water (SCW) hydrolysis of deoiled spent coffee ground (SCG) was conducted involving pretreatment with ultrasound (US‐SCG), and sample particle size reduction (PS‐SCG). SCW temperature, solid/liquid mixing ratio, constant pressure and residence time were studied for their effect on extracting reducing sugars (RS), total phenolic content (TPC), total flavonoid content (TFC), 5‐HMF, and furfural. Temperature increase enhanced hydrolysis efficiency and promoted RS dehydration into 5‐HMF and furfural. At 180 °C and 40 mg/600 mL, TPC, TFC and RS values increased significantly with ultrasound pretreatment correlating with improved antioxidant activities by DPPH and ABTS assays. Highest amount of 5‐HMF and furfural was obtained at 210°C (highest temperature studied) with 44.71 and 2.36 mg/100 g. Chlorogenic acid recovery was the highest in the non‐deoiled SCG (15.07 mg/100 g), with no significant difference observed in PS‐SCG, suggesting an increase due to its reduced particle size. The results of this study provide comprehensive knowledge on the combined effects of integrated engineering systems to boost the valorisation of SCGs into high‐value products.

Bi-level energy optimization model in smart integrated engineering systems using WSN

Based on fuzzy relational inequality, a bi-level linear programme optimizes the visible light brightness and operating costs of access points in a wireless transmission station system. Consider the first computing problem utilizing a minimum solution matrix. A convex infinite set is generated by a restricted number of closed intervals. Second, computing is an objective-domain nonlinear mathematical optimization problem. A multi-objective optimization problem is used to solve the second programming challenge. The constraint set must be used. Use discrete optimization techniques and branch-and-bound procedures for “digital integer linear programming”. Our technique has been shown to be both practical and successful. The programming complexity increases as the organization expands.

Environmental persistent free radicals in diesel engine exhaust particles at different altitudes and engine speeds

The occurrence of environmental persistent free radicals (EPFRs) in the environment has attracted a great deal of research attention. Although the major sources of EPFRs in the environment is diesel engine exhaust, the study on the emission characteristics of EPFRs at different working conditions is still very limited. An integrated engine system was adopted to simulate different working conditions of various altitudes and engine speeds, and to examine the emission process of a diesel engine. The results suggested that low engine speed and high altitude are generally associated with high PM10 emission with more stable and ordered structures. Based on the analysis of PAHs on solid and gas phases, PM10 generated from diesel engine at altitude higher than 2000 m may contain substantial amounts of PAHs embedded inside particles, but not adsorbed on the surface. EPFRs signal up to 1.66 × 1020 spins/g were detected in PM10 of the diesel exhaust. Higher engine speed and lower altitude were associated with stronger EPR signals on PM10. However, the accumulated EPR signal intensities after consuming 1 L of diesel were higher at lower engine speed and higher altitude, suggesting higher overall risks. A positive correlation between R value (signal strength ratio of D and G peaks on the Raman spectra) and EPFRs intensity indicated that the EPR signals were associated with the defects of carbon structure. EPFRs intensity in particles showed no significant change in dark, and over 70% of the EPR signals survived under UV light in a one-month aging simulation. The strong persistence of these EPFRs suggested their potential long lasting and widespread risks, which should be investigated extensively.

Performance-based control co-design of building structures with controlled rocking steel braced frames via neural dynamic model

Controlled rocking steel braced frames (CRSBFs) are modern systems for resilient building structures known for their effective energy dissipation and self-centering features. In a CRSBF, post-tensioned (PT) strands and shear fuses are the distinct features providing the self-centering and energy dissipation mechanisms. As a relatively new structural system, there is a need to study this system’s optimal design. Control co-design has gained interest in recent years as a class of integrated engineering system design methods as an alternative to the traditional approach of optimizing the structural design and sequentially optimizing the control system’s design. It considers the direct relationship between physical and control system design decisions to discover non-obvious design solutions that enable new performance and functionality levels. This paper proposes a performance-based control co-design methodology for building structures integrating CRSBFs that concurrently minimizes the mainframe weight and determines the CRSBF design parameters subject to design code requirements as the optimization constraints. The patented neural dynamic model of Adeli and Park is used in this research to solve the nonlinear optimization problem. The seismic performance evaluation of the proposed methodology includes a shear frame and a nonlinear 6-story 3D building structure. The 6-story building model consists of 282 nodes with 1,692 degrees of freedom. A total of 610 frame elements, 8 PT strands with nonlinear material, and 32 nonlinear links are determined without requiring high-performance computing. Results show that the energy dissipation mechanism effectively reduces the seismic demand in structural members. The proposed performance-based control co-design methodology can lead to 21% reduction in the total weight of the 6-story frame structure.

An integrated engineering system for maximizing bioenergy production from food waste

In this study, an integrated engineering system was developed for bioenergy production from food waste pretreated with a cost-effective and highly active enzyme mixture, namely fungal mash which was also in-situ produced from food waste. Under the optimized conditions, 141.5g/L of glucose was obtained with 67.5% of total solid reduction after hydrolysis of food waste by fungal mash, while 71.8g/L of bioethanol was produced from subsequent glucose fermentation. The remaining hydrolysis residue was further anaerobically digested for biomethane production with 22.8% of total solid reduction. As the result, about 90% of total solid reduction of food waste was achieved in the integrated engineering system with the outputs of bio-renewable energy in the forms of bioethanol and biomethane. The cost-benefit analysis clearly suggests that the bioenergy production from food waste in the proposed integrated engineering system is technically feasible and economically viable.

Real-time economic dispatch for the supply side of the energy-water nexus

Clean energy and water are two essential resources that any society must securely deliver. Their usage raises sustainability issues and questions of nations’ resilience in face of global changes and mega-trends such as population growth, global climate change, and economic growth. Traditionally, the infrastructure systems that deliver these precious commodities, the water distribution and power transmission networks are thought of as separate, uncoupled systems. However, in reality, they are very much coupled in what is commonly known as the energy-water nexus. Although this subject has recently caught the attention of numerous policy and regulatory agencies, rarely is it holistically addressed in terms of an integrated engineering system for its management, planning, and regulation as an interdisciplinary concern. This work specifically fills this gap by addressing the supply side of this integrated engineering system. Specifically, it develops the multi-plant real-time simultaneous economic dispatch of power and water. While significant background literature has addressed traditional power dispatch, and the emerging co-dispatch of power and heat, as of now there does not exist a parameterized model for the optimized dispatch of power and water for multiple power, water, and coproduction facilities. The work presents such a model where production costs are minimized subject to capacity, demand and process constraints. It is demonstrated on an illustrative example of modest size. Interesting results were observed suggesting that the coproduction minimum capacity limits and process constraints can lead to scenarios where cheaper single product plants can be crowded out of the dispatch. The program provides a systematic method of achieving optimal results and can serve as a basis for set-points upon which individual plants can implement their optimal control. In so doing, it makes a supply-side contribution to the ongoing grand-challenge of improving the sustainability of the energy-water nexus.

Optimal expansion of a coastal wastewater treatment and ocean outfall system under uncertainty (I): simulation analysis

An ocean outfall system is an integrated engineering system in which a coastal wastewater treatment plant (WWTP) is connected with a pipeline that discharges wastewater effluent into a body of water. Safety factors to accommodate for uncertainty in modelling of such systems often result in a degree of wastewater treatment that is not cost-effective. This paper presents the first part of an integrated simulation and optimisation analysis to resolve some such uncertainties in the Cornell mixing zone expert system (CORMIX) model by testing it against a laboratory flume. CORMIX is a United States Environmental Protection Agency (USEPA)-supported mixing zone model for environmental impact assessment of regulatory mixing zones resulting from continuous point source discharges. This model especially emphasises prediction of plume geometry, flow classification, and dilution characteristics within an initial mixing zone of a receiving water body so that compliance with regulatory constraints can be evaluated. With the aid of a flume test, such information may be used as stochastic inputs to an optimisation model to assess the cost-effectiveness of discharge treatment. A total of 19 dye-study scenarios were designed and carried out for single-port (co-flow or counter-flow) and multi-port experiments according to the physical features of the outfall pipe to be expanded in the coastal environment of Taiwan Strait. The flume test showed a good agreement between CORMIX1/CORMIX2 models and the dye-study data. This approach is a stepwise, flexible technique allowing for continuous feedback of the varying design and operating conditions and the observed impacts on coastal waters and may be used to identify the optimal expansion strategy of an integrated coastal WWTP and ocean outfall system such as the case study presented for Kaohsiung, South Taiwan.

액체 로켓 엔진시스템 개념설계를 위한 모듈화 프로그램 Part II: 통합 모듈화 프로그램

액체 로켓 엔진시스템 개념설계를 위하여 주요 엔진 구성품들에 대한 모듈 프로그램을 통합한 성능 설계 프로그램을 작성하였다. 구성품에 대한 모듈 프로그램은 설계 인자를 수학적으로 묘사하였고, 구성품 간의 유량과 압력을 매칭시켜 각 모듈 프로그램을 통합함으로써 반복계산을 통해 엔진 성능을 예측하는 모듈화 프로그램을 작성하였다. 구성품간의 유량이 조율되고, 유량의 함수로 계산된 각 구성품에서의 압력강하량을 합산하여 터보펌프 출구조건을 부여하도록 하였다. 프로그램의 계산과정과 설계방법을 간략하게 제시하고, 결과는 검증 모델 엔진의 데이터와 비교하여 검증하였다. With a view to building up a program used in conceptual design of liquid rocket engine system, a preliminary performance-based code for an integrated engine system has been developed by incorporating sub-modular programs for each essential engine component. Modular descriptions for each component were formulated mathematically with essential parameters. In the whole iterative circuits for predicting engine performance, matching conditions of mass flow rate and pressure drop through each engine component have been considered. Mass balance calculations at each inter-component boundary are found smoothly converged. All the pressure drops through engine components as a function of mass flow rate are added up to provide turbo-pump outlet condition. In this paper, the flow chart for each iterative circuit and design methodologies are presented. Resultant predictions are validated with real engine data.

Robust, Producible Design Process Evolution

ABSTRACT Until about 10 years ago, design engineering and manufacturing at our company were separate organizations. Design engineers produced part designs for an integrated engine system and expected manufacturing to make and assemble the parts. Tolerance decisions were influenced by the arguing ability of each discipline along with historic precedent. Most form-fit-function characteristics were about 95% producible or two-sigma designs. Nonconformance control by a Material Review Board (MRB) was used by design engineering to monitor manufacturing quality. Although this process demonstrated the ability to produce excellent engines, it depended on inspecting in quality, multiple rework loops and resulting high cost. This article will discuss the evolving process used to design engines that are producible and error proofed. Discussion will include the organizational structure supporting the needed culture change, the six-sigma impact of common terminology and data driven decisions, the structured approach using manufacturing process capability data to facilitate producibility, use of assembly defect and customer escape data to drive error-proofing early during the design process, and the focus on standardized notes and automated characteristic accountability for error prevention. Discussion will include examples demonstrating the significant improvements in quality and producibility accomplished by the new process.

Reconstruction of the cast house of a blast furnace

The use of an integrated engineering system in the reconstruction of cast houses makes it possible to make more efficient use of blast furnaces based on several characteristics: it improves the working conditions for furnace personnel (hearth attendants) involved in tapping the smelting products; it reduces the amount of heat lost from the pig iron by maintaining its initial temperature; it reduces the amount of pig iron lost with the slag; it significantly decreases the volume of pollutants generated; it reduces penalties for polluting the environment.

A communication model for structural design objects. I: Channels and medium

Design objects of integrated engineering systems frequently communicate data and information among each other. The data to be communicated is usually characterized by considerable variability in format and structure. This warrants the development of a uniform mechanism for communicating data and information among design objects. Recent advances in the object-oriented paradigm and the emerging agent-oriented paradigm gave promise to the development of such mechanism for inter-object communication that was difficult to achieve previously. This paper and its companion paper address this issue and propose an object communication model. Specifically, this paper identifies the communication channels among structural engineering design objects and proposes a communication medium based on messenger object for conveying message arguments and responses. The unified modeling language (UML) is used to present the model and its ingredients. A note on implementation of the messenger object, using C++ STL, is shown. Examples to demonstrate the capability of the communication model are presented. The proposed communication model will impose a uniform and consistent mechanism for communicating data and information among design objects. Other ingredients of the communication model such as performatives and protocols are addressed in the companion paper.

Representing and analysing integrated engineering systems through combinatorial representations

The current paper introduces a systematic method for representing and analysing coupled integrated engineering systems by means of general discrete mathematical models, called Combinatorial Representations, that can be conveniently implemented in computers. The combinatorial representation of this paper, which is based on graph theory, was previously shown to be useful in representing engineering systems from different engineering domains. Once all of the subsystems of an integrated multidisciplinary system are brought up to the common level of the combinatorial representation, they cease to be separated from one another and the analysis process is applied to all of the engineering elements disregarding the domain to which they belong.During the development of the representation and study of its inherent properties, special attention was dedicated to developing an efficient analysis method. A vectorial extension of the mixed variable method known from electrical network theory was found to be the most suitable choice for this purpose.In the paper, the approach is implemented by representing and analysing two systems: one that is a macro system comprised of truss, dynamic and electric elements, and another that is a comb-driven micro-resonator. The techniques presented in the paper are not limited to analysis only, but can be applied to many other aspects of engineering research. Among them is a systematic derivation of new ways of presenting engineering elements, one of which – the process of derivation of a new type of force representation entitled “face force” – is described in the paper.

Object oriented paradigms for integrated structural engineering

The increase in use of computers in many aspects of engineering constructed facilities has been enormous during the past few decades. Computers are used for analyses of structures, design checks and optimization, cost estimation, construction planning, etc. Using proven algorithms, many of the individual tasks are now highly automated and tools such as neural networks, expert systems, genetic algorithms, and hybrid systems have shown promise for automation for some of the previously unapproachable problems. However, an important issue facing efficient use of computers in engineering today involves integration of many of these tasks and a productive structural engineering system must be an integrated software system. The fundamental interface to the resources in a computer system that engineers need to face in developing an integrated engineering system are a programming paradigm and a data model to represent engineering information in the database. Object oriented concepts and paradigms have been used successfully to develop large systems. After a brief review of integrated structural engineering systems, this paper presents an object oriented data model that can effectively represent engineering information in the central database of an integrated structural engineering system. The model treats classes as objects and message sending is the only mechanism necessary for communication among data objects, database users and database administrators. This results in a model that is simple and uniform.

Standards processing in an integrated engineering system

This paper discusses a standards processing architecture in integrated systems to handle different standards at different stages of the engineering design process, using the blackboard problem solving model. The standards processing model is based on the semantic mapping between the standard-independent and standard-dependent knowledge represented independently in separate knowledge sources. The semantic mapping in a coordinating knowledge source allows direct interaction of independently developed knowledge sources for efficient reasoning. The architecture provides a knowledge-based backtracking facility to handle failures. The model described here forms part of a project on the development of an integrated knowledge-based expert system for engineering of steel structures (covering planning, analysis, detailed design and construction management activities). The standards processing concepts are illustrated with the help of a loading standards processing and a design standards processing in the design of steel industrial structures.

An artifact modeling approach for developing integrated engineering systems

Engineering problem solving can be viewed as a transformation process in which the initial description of an engineering system (artifact) transforms to its final description. This paper presents a single yet powerful approach for modeling engineering artifacts. The approach involves using (1) a symbolic language for representing engineering artifacts in terms of objects and relations and (2) a mechanical strategy for manipulating engineering artifacts. The approach provides a common platform for modeling different phases of the engineering problem solving process, thus facilitating system integration.

A communication model to aid knowledge-based design systems

Recent research in the area of computer-aided engineering design has focused on the development of environments that provide effective integration of several domain specialties for complex multidisciplinary synthesis problems. The definition of communication requirements for co-operative interaction—and the subsequent establishment of a conceptual model for automating the process—are important considerations in the development of such environments. A communication model can also provide the basis for development of a knowledge engineering strategy by defining the organizational and representational requirements for domain knowledge in the automated system. This paper presents a conceptual model for communication in automated interactive design and demonstrates how the model can be employed as a knowledge engineering tool to facilitate the acquisition and organization of domain expertise. Both the process architecture and semantic modeling aspects of the communication problem are considered. An example is included which illustrates the use of the model in formulating an automated integrated engineering system in the domain of floor and equipment layout and design for industrial facilities.