Simple Design Procedure Research Articles

A Novel Double U-Slot Microstrip Patch Antenna Design for Low-Profile and Broad Bandwidth Applications

A low-profile double U-slot microstrip patch antenna with a wide operating bandwidth has been developed in this article. This design produces the dual radiative resonant modes adjacent to each even at the thickness of the antenna of <inline-formula> <tex-math notation="LaTeX">$0.02 {\lambda _{0}}$ </tex-math></inline-formula>. An extremely stable radiation gain that varied from 6.2 to 6.8 dBi is achieved within the whole operating band. In addition, detailed parametric studies in this article provide antenna engineers with simple approximate rules that result in an excellent first-pass design with prescribed characteristics requiring only minimal tuning. Finally, the proposed antenna with the thickness of <inline-formula> <tex-math notation="LaTeX">$0.04 {\lambda _{0}}$ </tex-math></inline-formula> is fabricated and measured. Simulated and measured results are found in good agreement with each other. They have evidently illustrated that the bandwidth is increased by 50&#x0025; compared to the traditional U-slot antenna. With the help of these simple design procedures and examples in this article, antenna designers could easily develop a low-profile broadband antenna.

An Equivalent Circuit/System by Design Approach to the Design of Reflection-Type Dual-Band Circular Polarizers

A dual-band reflection-mode wide-bandwidth and wide-angle scanning circular polarizer is designed. The proposed polarizer can convert linearly polarized waves into right- and left-hand circularly polarized (RHCP and LHCP) waves in the two separate nonadjacent receiving and transmitting K/Ka frequency bands. The polarizer is based on dual-layer dipole arrays printed on both sides of a dielectric substrate separated by a second substrate from the ground plane. An analytic model based on transmission line equivalent circuits is developed. Closed-form expressions are derived to demonstrate the operating principle providing a simple design procedure. The proposed model can be used to optimize the converter for a specific propagation angle of the incident wave. Finally, a system-by-design (SbD) strategy is proposed to improve the performance of analytically synthesized devices. Toward this goal, a computationally efficient “digital twin” of the accurate full-wave model is built to speed up the solution space exploration and efficiently reach the global optimum. A prototype is designed for the incident angle <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\theta _{0} = 30^{\circ }$ </tex-math></inline-formula> and it is shown that the axial ratio lower than 3 dB is maintained for a wide-angle field of view of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta \theta = 60^{\circ }$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\theta }_{min}=0^{\circ },{\theta }_{max}=60^{\circ }$ </tex-math></inline-formula> ) in both frequency bands.

Theoretical framework for estimating design reactor pressure for water-based hydrothermal carbonization (HTC) systems

Hydrothermal carbonization (HTC) has been shown to be a valuable system component in sustainable management strategies for wet organic residues from agriculture, industries and municipalities. While the reaction temperatures in HTC are much lower than those in alternative thermochemical processes, the pressures reached in HTC are much higher, rising with temperature as the autogenic pressure of water rises, and as reaction gas is produced from hydrothermal reactions. An important basis for designing cost-effective equipment for the HTC systems is understanding the safety aspects and costs associated with the reactor pressure. This paper presents a theoretical framework to predict the expected HTC reactor pressure for hydrothermal reactions with biomass that produce CO2. A model was developed that uses the thermodynamic properties of CO2-water mixtures at HTC reaction conditions and was validated using well-defined experiments with CO2-H2O. Comparison of the pressures predicted by the theoretical model to actual pressures in HTC reactions with real biomass (bark mulch, sugar beet pulp) showed relative errors ranging from −18.5% to 7.3%. A simple design procedure was suggested to predict HTC reactor pressure and demonstrated on a further case. The results of a sensitivity analysis showed that the pressure estimation is most affected by the parameters related to the amount of CO2 formed during the HTC reaction. The easy-to-follow methodology developed in this study will help researchers, design engineers, and manufacturers to estimate the pressure reached in the HTC reactor based on desired design goals and promote the widespread use of HTC for converting wet wastes into value added hydrochar which can improve soil health and reduce environmental pollution.

Real-time hybrid simulation for a base-isolated building with the transmissibility-based semi-active controller

The transmissibility-based semi-active (TSA) controller was developed in the existing study by the authors, which can effectively enhance the performance of base-isolated buildings under both strong long- and short-period earthquake ground motions. Since the performance of the TSA controller was only evaluated with numerical simulation in the existing study, this paper further validates its performance experimentally by conducting real-time hybrid simulation (RTHS). A three-story base isolated building was designed based on a simplified design procedure, where the base isolation system of the building consisted of three different devices, that is, a magneto-rheological (MR) damper, rubber bearing, and linear bearings. The base isolation system was experimentally tested with the MR damper controlled by the TSA controller, and the building superstructure was analytically modeled. It was shown that the TSA controller makes the system damping high under long-period ground motions and low under short-period ground motions, which performed uniquely as intended. As a result, the isolator displacement was effectively reduced under long-period ground motions, while the story drift and acceleration responses were also reduced under short-period ground motions, all of which are difficult to achieve at the same time using passive damping only.

Dynamic Response Prediction of RC Structural Components Subjected to Combined Blast and Fragment Impact

The paper presents a methodology for enumerating the dynamic response of one-way reinforced concrete (RC) structural elements subjected to combined blast and fragment loading, a scenario commonly associated with the detonation of cased explosive charges. The proposed methodology is motivated by the relatively few studies published in this area and the simplified design procedures that are currently used for addressing this problem. The formulated framework, in addition to the consideration of the blast and the fragment loading, also accounts for the damage incurred by the member due to the localized penetration caused by the impacting fragments. The fragment-induced damage is accounted for by considering a member having a reduced cross-sectional depth, i.e., a damaged member. Material nonlinearity and the strain rate–sensitive aspects of both concrete and steel are also considered. The dynamic structural response of the member was quantified by idealizing the member as an equivalent single-degree-of-freedom system. Finite-element (FE) simulations were conducted by the authors for assessing the efficacy of the adopted formulations. On the basis of the comparative assessment, the results of the FE simulations were found to match relatively well with the results of the proposed approach (relative difference being in the range of 8.95%–12.67%). Additionally, the peak displacements for the cased explosive charges were noted to increase by approximately 31%–123% compared to bare (uncased) explosive charges of similar charge weights. While this observation underlines the severity of cased explosive charges, it also qualitatively highlights the damaging propensity of the striking fragments, a component that generally is not exclusively considered for design purposes.

Simplified Structural Analysis and Design Procedures for Sulfur Recovery Units

AbstractThis paper presents cost-effective guidelines for practicing engineers to design, evaluate, or review the structural design of the sulfur recovery unit (SRU) used in refineries. Extensive e...

Application-Specific Adaptable Coatings for Sensors: Using a Single Polymer-Plasticizer Pair to Detect Aromatic Hydrocarbons, Mixtures, and Interferents in Water with Single Sensors and Arrays.

A relatively simple design procedure is presented for new, adaptable chemical sensor coatings made from a single polymer-plasticizer pair to detect single or a mixture of chemical compounds (e.g., BTEX, the small aromatic hydrocarbon family). Affinity between coating components and target analytes, expressed through Hansen solubility parameters and relative energy difference values, describes the sensitivity of the resultant coatings to each analyte. While analyte affinity is paramount for plasticizer selection, for the aqueous-phase sensing application described here, it must be traded off with the permanence in the host polymer, i.e., resistance to leaching into the ambient aqueous phase; deleterious effects including coating creep must also be minimized. By varying the polymer:plasticizer mixing ratio, the physical and chemical properties of the resultant coatings can be tuned across a range of sensing properties, in particular the differential response magnitude and rate, for multiple analytes. Together with the measurement of multiple sensor response parameters (relative sensitivity and response time constant) for each coating, this approach allows for identification and quantification of target analytes not previously separable using commercial off-the-shelf (COTS) polymer sensor coatings. Sensing results using a five-sensor array based on five different mixing ratios of a single plasticizer polymer pair (plasticizer: ditridecyl phthalate; polymer: polystyrene) demonstrate unique identification of mixtures of BTEX analytes, including differentiation of the chemical isomers ethylbenzene and total xylene (or "xylenes"), something not previously feasible for separation-free liquid-phase sensing with commercially available polymer coatings. Ultimately, the response of a single optimized sensor coating identified and quantified the components of various mixtures, including identification of likely interferents, using a customized estimation-theory-based multivariate signal-processing technique.

Design of a novel seismic retrofitting system for RC structures based on asymmetric friction connections and CLT panels

Friction-based dampers are a valid solution for non-invasive seismic retrofitting interventions of existing structures, particularly reinforced-concrete (RC) structures. The design of friction-based dampers is challenging: underestimating the slip force prevents the full use of the potential of the device, which attains the maximum admissible displacement earlier than expected. By contrast, overestimating the slip force may cause delayed triggering of the device when the structure has suffered extensive damage. Therefore, designing the appropriate slip force is an optimization problem. The optimal slip force guarantees the highest inter-story drift reduction. The authors formulated the optimization problem for designing a specific class of friction-based dampers, the asymmetric friction connection (AFC), devised as part of the ongoing multidisciplinary Horizon 2020 research project e-SAFE (Energy and Seismic AFfordable rEnovation solutions). The seismic retrofitting technology involves the external application of modular prefabricated cross-laminated timber (CLT) panels on existing external walls. Friction dampers connect the CLT panels to the beams of two consecutive floors. The friction depends on the mutual sliding of two metal plates, pressed against each other by preloaded bolts. This study determines the optimal slip force, which guarantees the best seismic performance of an RC structural archetype. The authors investigate the nonlinear dynamic response of a coupled mechanical system (RC frame-friction damper) under a set of strong-motion earthquakes, using non-differential hysteresis models calibrated on the experimental cyclic responses. The solution of the optimization leads to the proposal of a preliminary simplified design procedure, useful for practitioners.

Ultra‐broadband metamaterial absorbers based on spoof surface plasmon polaritons structure

AbstractInspired by the dispersion engineering of spoof surface plasmon polaritons, in this paper, a comprehensive scheme is proposed, which firstly develops a plasmonic absorbing structure (PAS) with wide absorption band and high angular stability. The PAS unit cell is composed of a graded metallic strip array printed on a dielectric grid and backed with a metal ground. It realizes wideband absorption in the frequency range of 18–37 GHz. Moreover, a commercial absorbing film is further integrated with the proposed PAS to expand the overall absorption bandwidth covering around 5.5–55 GHz without increasing the thickness of the whole structure excessively. Simulated and experimental results show that the proposed hybrid metamaterial absorber can provide ultra‐broadband absorption with simple design procedure and light weight, allowing potential applications such as RCS reduction of antennas, electromagnetic shielding, and so on.

Behavior of different bolted connection configurations in frames composed of cold-formed sections

Rigid bolted cold-formed steel connections have been very popular for their better distribution of straining actions and for better full-filling serviceability requirements. However, the behavior of every single element in the connection as well as the interaction between them is not clear due to its complex behavior. A nonlinear finite element parametric study was conducted on the apex knee connection of a portal frame constructed with cold-formed back-to-back double-lipped C sections for both the rafter and the column. These back-to-back lipped C sections, connected by gusset plates are used as beam and column members. Only the webs of lipped C sections are connected to the connection gusset plates with bolts. The section flanges are not connected to the columns for ease of construction. The study focused on investigating the effect of different parameters on the ultimate capacity and the failure mode of the eave connection. Studied parameters include different bolt configurations, bolt diameters, gusset plate thickness, the bolt pre-tensioning force, and the edge distance. The effect of bolt bearing on the C-section web was considered in the calculation of the capacity of the connection. Five modes of failure were identified namely; lateral out-of-plane buckling of the gusset plate, local buckling of the connected section, bolt bearing of C-section web and the gusset plate, tearing of C-section web. It was observed that bearing failure is the dominant mode of failure. However, in some cases, the lateral-out-of-plane buckling of the gusset plate takes place and causes the premature failure of the connections at low values of applied loads. The local failure of the connected sections occurs at the ultimate loading phase. Several observations were found and some useful recommendations for optimum connection configuration are suggested. A simple interaction design procedure for special configuration to calculate the resistance of the joint connection under moment, shear, and normal forces based on the bolt bearing failure for different bolt pitches is proposed.

Multibit Chipless RFID Tags Based on the Transition Among Closed- and Open-Loop Resonators

In this article, a novel and simple design procedure for multibit chipless radio frequency identification (RFID) tags is introduced, which is based on the characteristics of dual-mode loop resonator (DMLR) and open-loop resonator (OLR). By removing a small patch element from the symmetry axis of the DMLR, a simple geometrical transition to an OLR to obtain different frequency codes can be achieved. Since the DMLR and OLR provide dual- and single-resonant frequencies, three different frequency codes can be observed using one resonator. Thus, 3 <formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex>$^{N}$</tex> </formula> codes can be performed by coupling N resonators to input/output (I/O) ports. Even-odd mode analysis over the coupling mechanism of a single resonator is provided to characterize the frequency responses of the proposed resonators. To prove the proposed approach, two multiresonator circuits having four resonators were fabricated and tested in a good agreement. In the test environment, two horn antennas and a vector network analyzer have been utilized as transmitter and reader. Next, in order to achieve size reduction, meandered resonators are utilized instead of conventional DMLR and OLR. Based on these resonators, two RFID tags, including wideband monopole antennas integrated into the seven-resonator circuits on the same board, were also fabricated and tested.

Direct Data-Driven Design for a Sparse Feedback Controller Based on VRFT and LASSO regression

Direct data-driven controller design has attracted considerable attention because of simple design procedure. This paper presents a direct model-referenced data-driven design for obtaining sparse controller to prevent over learning from single-experiment data. In conventional methods, controller parameters are obtained for controller with order defined by user. In case where there is little plant information, it is difficult to define controller order to achieve model-matching. Also, if high order of the controller is simply set, over learning may occur. Thus, the sparse controller design method is proposed. The proposed method is based on VRFT (virtual reference feedback tuning) and LASSO (least absolute shrinkage and selection operator) regression. A simulation is performed to verify the proposed method. The results show that the sparse controller can be obtained for the controller with high order.

A simplified design procedure for seismic upgrade of frame structures equipped with hysteretic dampers

This paper presents a simple and affordable design procedure for the seismic upgrade of frame structures equipped with hysteretic dampers. The proposed framework is aimed at leading the designer to proportion the damper device(s)) in order to achieve a desired structural performance level. According to the method, the structural system composed by frame and dampers is replaced by an equivalent Single Degree of Freedom (SDOF) system, characterized through its secant stiffness and equivalent viscous damping, both defined in relation to a “performance point” which is assigned on the basis of the allowable damage of the frame and on the first mode deformation of the main structure. The global stiffness and strength of the equivalent SDOF system are then distributed along the height of the frame according to a stiffness-proportionality criterion, and the properties of the damper units are calculated depending on the chosen layout. Two case-studies relevant to as many reinforced concrete frames are provided to demonstrate the effectiveness of the suggested procedure, obtaining a satisfactory agreement between the design target and numerical capacity curves. Non-linear dynamic analyses are further performed to assess the reliability of the methodology.

Design framework for a lean warehouse – a case study-based approach

PurposeThis purpose of this study is to develop a simple framework for designing a warehouse incorporating lean principles. Multiple objectives like resource planning, material handling, storage, inventory management, including internal and external logistics, are considered.Design/methodology/approachA design procedure to incorporate lean principles for designing a warehouse for a complex multi-model production line has been proposed. The preferred standards and factors affecting warehouse design, the inputs and outputs of process flow characteristics, are incorporated into the design. Current and future state value stream mappings are drawn to bring out the challenges in the value flow.FindingsThe framework for designing a lean warehouse have been implemented and validated in a heavy machinery manufacturer. This framework will ease the work of the future lean-based warehouse designers to apply simple step-by-step processes to achieve the goal with the nearest accuracy. The steps followed can be summarized as defining the lean processes, making the lean process as the design base, collecting inputs like stock-keeping unit master, inventory and space details, and building the lean warehouse design with the step-by-step processes.Practical implicationsPractical tips on warehouse design have been explained focusing on the part volume, quantity handled, inventory and throughput. This will assist the practitioners in designing a lean warehouse and leading to an improved operational performance.Originality/valueA simplified design procedure for designing a lean warehouse, along with a real-time case study has been enumerated in detail. Effective use of space and resources with lean tools and techniques lead to better storage and picking efficiency resulting in an overall reduction in cost.

Simplified design procedures for the structural analysis of reinforced concrete columns in fire

Simple analytical procedures are described to predict the structural behavior (axial displacements and failure) of reinforced concrete (RC) columns exposed to fire. The analyses assume a concentric load (no initial eccentricity) or an equivalent axial load to take into account first and second order effects. The main objective is to provide reliable and straightforward tools for a preliminary assessment of the structural integrity of RC columns. The procedures compute the total displacements and the failure (time and type) of RC columns with different concrete strengths (normal to ultra-high performance), shapes, fire incidences, load levels and initial eccentricities. The results of 24 experimental tests from different authors are predicted and compared with the analytical solution. The displacements are estimated by the introduction of EN 1992-1-2 (2004) stress–strain curves and a simplified bilinear constitutive law that takes into account the Load Induced Thermal Strain (LITS) as a reciprocal to the modulus of elasticity. In general, a good agreement with the experimental time vs. displacement curves was obtained. Failure is predicted with the adoption of the nominal stiffness method (EN 1992-1-2, 2004) to take into account the second order effects. Sectional analyses (axial-bending equilibrium) and simplified analytical procedures assuming an equivalent axial load replacing the axial-bending force (force equilibrium) are carried out. The results of both analyses were very close, indicating the reliability of the simplified procedure. The prediction of the fire resistance time demonstrated a good approximation, on the safe side, with the experimental data. The results are compared with the EN 1992-1-2 (2004) prescriptive formula.

A Novel Aperture-Loaded Decoupling Concept for Patch Antenna Arrays

In this article, a novel decoupling approach is proposed for large-scale patch antenna arrays. With the additional coupling path from the feeding line of an element to its adjacent element through a small aperture, the mutual coupling between the two elements can be well canceled. Completely different from the traditional transmission-line-based decoupling methods, the proposed approach does not employ direct transmission/coupling bridges between the feeding lines of the elements. Besides, there is no additional impedance matching network, resulting in a simple design procedure. For verification purposes, a decoupled dual-polarized 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 8 linear antenna array is developed and tested. Results denote that both the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> - and the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$H$ </tex-math></inline-formula> -plane coupling are suppressed to less than −30 dB at the center frequency of 4.9 GHz. To further improve the decoupling bandwidth, a magnitude-compensation technique using a dual-aperture configuration is developed. A design example of a 4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 4 single-polarized patch antenna array integrated with the decoupling method is measured. The results depict that the array is well-decoupled within the band from 4.7 to 5.04 GHz, with an isolation level of over 24.7 dB. The proposed decoupling approach features simple implementation and low profile, with almost no influence on element radiation performance, and can be utilized for 2-D large-scale arrays.

Basic design procedure for an internally geared screw compressor

The internally geared gerotor type of positive displacement machine is widely used for pumping applications, but can also be used to achieve internal compression or expansion of a working fluid. A further development of this configuration is the application of helical twist to the inner and outer rotors. Previous studies have shown that this can decrease the power transferred between rotors, and increase the relative maximum flow areas at the inlet and discharge ports. There are possible benefits to this configuration when compared to conventional twin-screw machines, including reduced leakage area, stiffer rotors, and co-directional thermal expansion of rotors. However, no experimental data is currently available for this configuration, and optimising the geometry of the gerotor screw machine requires a detailed understanding of the porting, leakage flows and mechanical losses. An experimental programme is being conducted to investigate the influence of these factors on performance. This paper discusses preliminary results from geometrical analysis leading to a simple design procedure. The basic design of an internally geared air compressor is demonstrated, based on the operation characteristics of a conventional twin screw machine.

Comparative study of geometrical properties and simplified preliminary design procedure for concrete arch bridges

AbstractThis paper first presents a comprehensive database of 58 (specifically, 38 roadway and 20 railway) concrete arch bridges built in Spain during the last century. The collected information includes geometrical and mechanical data to define the main relations among different parameters and to identify specific trends. In addition, this information has been combined with data collected by other authors to compare results with other worldwide bridges with similar features. In summary, 112 concrete arch bridges covering a span range from 12 to 384 meters have been used to investigate relations of a variety of parameters such as flatness, arch and girder depths, bending stiffness, slenderness, effective slab thickness and dimensionless axial forces. Finally, based on this study, a data‐drive simplified procedure for the preliminary design of such bridges is proposed.

Review on Analysis of Free Vibrational Horizontally Curved Bridges

Curved I-girder concrete bridges give an outstanding answer to urban congestion, traffic, and pollution concerns, but the combined flexibility and torque responses of the bridges make their behavior exceedingly complex. That is why structural design parameters for simplified design procedures are in high demand, as measured by empirical equations. To analyze the effect on the free vibrational reaction of curve composite steel-concreteI-girder bridge with varying vibration parameters, this research employs a sensitivity analysis. To learn the fundamental frequency and the geometric configuration of the model forms, a parametric investigation is performed. Finite element Modelling of composite steel/concrete frameworks, deformable shear model, fine element formula, finite element mounting, finite element calibration, and finite element modeling, etc. Modeling finite element. Sensitivity research to draw the fundamental frequencies for the evaluated bridges. The parametric research outcomes. The results. Curved I-girder bridges of composite steel with single span or multi-span lengths are presented.

Simplified seismic design procedure for steel MRF structure with nonlinear viscous dampers

This paper presents a simplified design procedure (SDP) for performance-based design of low-rise new steel MRF buildings with nonlinear viscous dampers. The SDP uses an effective stiffness and equivalent damping for a multi degree-of-freedom (MDOF) model of the MRF building, which is established using a linearized model of the damping system (damping devices and the associated bracing). The SDP is an integrated design process for the steel MRF and the damping system to achieve target performance objectives. The SDP is consistent with the analysis procedures in ASCE 7–16 for seismic design of conventional structures without dampers, however, differentiated from the analysis procedures for structures with dampers without the computation of effective period and effective damping ratio as a function of the ductility demand on the structure. The SDP was validated using nonlinear dynamic time history analyses (NDTHA) results for a 4-story example steel MRF building with nonlinear viscous dampers with two scenarios of damper arrangements in the building. The MRFs were designed for various base shear design strength levels (i.e., 100%, 75%, 60%, 50% and 40% of the required base shear design strength of ASCE 7–16), and nonlinear viscous dampers were sized and added to the MRFs to control the story drift response. The results presented in this paper show that performance objectives for the SDP can be selected and achieved using a MRF designed with smaller base shear design strength than a conventional MRF.