Geometric Design Parameters Research Articles

CFD based analysis of 3D printed nasopharyngeal swabs for COVID-19 diagnostics

Background and ObjectiveAdditive manufacturing of nasopharyngeal (NP) swabs using 3D printing technology presents a viable alternative to address the immediate shortage problem of standard flock-headed swabs for rapid COVID-19 testing. Recently, several geometrical designs have been proposed for 3D printed NP swabs and their clinical trials are already underway. During clinical testing of the NP swabs, one of the key criteria to compare the efficacy of 3D printed swabs with traditional swabs is the collection efficiency. In this study, we report a numerical framework to investigate the collection efficiency of swabs utilizing the computational fluid dynamics (CFD) approach. MethodsThree-dimensional computational domain comprising of NP swab dipped in the liquid has been considered in this study to mimic the dip test procedure. The volume of fluid (VOF) method has been employed to track the liquid-air interface as the NP swab is pulled out of the liquid. The governing equations of the multiphase model have been solved utilizing finite-volume-based ANSYS Fluent software by imposing appropriate boundary conditions. Taguchi's based design of experiment analysis has also been conducted to evaluate the influence of geometric design parameters on the collection efficiency of NP swabs. The developed model has been validated by comparing the numerically predicted collection efficiency of different 3D printed NP swabs with the experimental findings. ResultsNumerical predictions of the CFD model are in good agreement with the experimental results. It has been found that there prevails huge variability in the collection efficiency of the 3D printed designs of NP swabs available in the literature, ranging from 2 µl to 120 µl. Furthermore, even the smallest alteration in the geometric design parameter of the 3D printed NP swab results in significant changes in the amount of fluid captured. ConclusionsThe proposed framework would assist in quantifying the collection efficiency of the 3D printed designs of NP swabs, rapidly and at a low cost. Moreover, we demonstrate that the developed framework can be extended to optimize the designs of 3D printed swabs to drastically improve the performances of the existing designs and achieve comparable efficacy to that of conventionally manufactured swabs.

GEODETIC SUPPLY FOR THE CONSTRUCTION OF ENGINEERING STRUCTURES

The construction of engineering structures when transferring the project to the area is impossible without geodetic work. The composition and sequence of engineering and geodetic works depend on the features of the design and construction of facilities and the type of structure. The purpose of the article is to consider geodetic works in the construction of engineering structures. The issues of performing engineering and geodetic works during the construction of structural elements of the bridge are considered. During the construction process, it is necessary to ensure full compliance with the design documentation and high accuracy of work performance. These requirements can be achieved by using high-precision geodetic works with constant monitoring of the installation work. At all stages of the bridge construction, geodetic works accompany the transfer to the terrain of the bridge axis, the resistance axis, perform a detailed breakdown during the construction of resistances and the installation of purlins. Also, the construction of individual parts of the building is constantly monitored, the dimensions and shape of the mounting elements are checked. When building large structures, it is necessary to have information about the points of the geodetic base of the bridge crossing, an extract from the catalog of coordinates and elevations of the geodetic base. The breakdown is carried out by tying to the points of the geodetic reference network, which has coordinates in the absolute or conditional system. Modern construction requires the use of new technologies and methods for performing geodetic work related to the introduction of electronic devices and programs for automated information processing into geodetic practice. Currently, a large number of geodetic instruments and new technologies in geodesy have been created, which differ from traditional ones. To carry out survey work, geodetic instruments, such as electronic total station and levels, were used. The electronic total station measures distances, angles and processes data directly in the process of field work, has an internal memory where it can store all the data obtained as a result of measurements. The digital level has a device for automatic registration of measurements along the rail and a processor for subsequent processing of all leveling results. During measurements, the device measures the distance to the rail and the elevation between points. This eliminates two main types of errors: observation errors when taking a reading and error in distance measurements. During the construction of supports, a temporary rapper is installed on each of them, which is tied to permanent rappers by leveling moves. The removal of marks on the supports is carried out by methods of geometric or trigonometric leveling. The coordinates of the rappers were received and entered into the local plan. Marks for serifs of the device with a retroreflective effect were pasted on the bridge supports. The data of coordinates and heights were entered into the total station memory. Geodetic work carried out during the construction of the span structure ensures the accuracy of its assembly in accordance with the project. After the installation is completed, the assembly results and deviations from the project are monitored. The construction of structural elements of engineering structures must comply with building codes and geometric parameters of the facility design.

Analysis and prediction models for operating speed of vehicles in expressway superlong tunnels based on geometric and traffic related parameters

Objectives Operating speeds on roads are critical indicators for evaluating traffic safety. Currently available research on the operating speed’s prediction focuses on open roads and highways. Insufficient attention has been paid, so far, to tunnels, which form bottlenecks on expressways. The present research aims to establish an operating speed prediction model for tunnels and analyze the influence of their geometric parameters on the operating speeds of vehicles. Methods We consider the speed of vehicles collected through field measurements in the portals and lay-bys of six superlong tunnels (length greater than 3000 ). Using linear regression, a prediction model for the speed in an expressway superlong tunnel is obtained considering tunnel’s geometric parameters. The influence of various parameters on the operating speed are analyzed through comparisons with existing research findings. Results We establish the first operating speed prediction model for tunnels considering geometric parameters and find that the vehicle type is the most important parameter affecting the operating speed. Other important parameters include the preceding curve length up to speed observation point (), preceding tangent length () and preceding tangent length up to speed observation point (). Conclusions The influence of geometric parameters on vehicle operating speed in super long tunnels differs from that observed in non-tunnel roadways. The effects of the preceding or subsequent curve radius ( or ) of the tangent section, curvature (), and curve degree () are not important in this case. Furthermore, we find that the influence of the posted speed limit () is closely related to the driving scene and safety awareness of drivers. These findings can improve the design and joint evaluation of tunnel geometric parameters and traffic safety.

Dynamic model of a robotic platform with 6 degrees of freedom

The paper presents the study of kinematic and dynamic characteristics of the robotic mobility platform (RMP) to determine inertia-force parameters depending on the nature of the implemented motion path. The method is implemented on the basis of parameterized digital simulation models with parallel kinematics, which allow determining acceleration and force response in the joints of structural components at given geometric parameters of the platform design.

Numerical Size Optimization of Cervical Spine Disc Prosthesis Mobi-C Using Design of Experiment Technics

The cervical spine is a structure subject to various vertebral injuries, namely, herniation of intervertebral discs and osteoporosis. Nowadays, several segments of society are vulnerable to these diseases that affect spine motion especially elderly people and women. Hence, various designs of cervical artificial discs are in use or under investigation claiming to restore the normal kinematics of the cervical spine. In this work, it is proposed to minimize the stress level by numerical size optimization in the Mobi-C cervical spine prosthesis to improve their biomechanical performances. For this aim, design of experiment (DoE) is employed as an optimization technique to investigate three geometrical parameters of the prosthesis design. Accordingly, DoE optimization allowed to minimize the equivalent stress value on Mobi-C from 20.3 MPa to 17.856 MPa corresponding to a percentage decrease of 12% from the original geometry. This provides an advantage for the durability of the prosthesis and also for the bone by reducing stress concentration.

ОСОБЕННОСТИ ОБРАБОТКИ ДЕТАЛЕЙ ИЗ ПОЛИМЕРНЫХ МАТЕРИАЛОВ ЛЕЗВИЙНЫМИ ИНСТРУМЕНТАМИ

The study objective is to select the tool cutting part materials and to assign the operating parameters taking into account the properties of polymer materials that characterize their machinability. The problems to which the paper is devoted are experimental studies of ways to expand the technological capabilities of cutting polymer materials. Research methods: experimental studies are conducted on the basis of the main provisions of the engineering technology, the theory of elasticity and plasticity. Experimental studies are carried out according to standard methods in production and laboratory conditions with the use of certified control and measuring equipment. The obtained data are processed using computational techniques and presented in the form of empirical dependencies convenient for practical application. The novelty of the work consists in conducting experimental studies of choosing materials for the tool cutting parts and their design features and geometric parameters, as well as in obtaining the operating parameters of machining parts made of polymer materials.
 Conclusions: On the basis of experimental studies, the ways of expanding the technological capabilities of cutting polymer materials are chosen.

Design and analysis of the optimal spinning top-shaped buoy for wave energy harvesting in low energy density seas for sustainable marine aquaculture

The floating buoys are an emerging source for renewable energy harvesting using ocean waves. Various point absorbers have been developed based on multi-freedom oscillating structures to capture wave energy. However, the choice of geometrical parameters for buoy design is still a critical problem. This paper presents a novel method to develop new geometries of floating buoy for wave energy harvester (WEH) in heave motion and aims to maximize WEH absorbed power and performance. Fives shapes (Cyl-Cone, Cyl-HS, Cyl-TCC, Cyl-AS and Cyl-SP) were derived from a cylinder buoy based on identical parameters (radius, draft, mass, water-plane area, volume and natural frequency). The Cyl-HS buoy was selected as a reference buoy for comparative analysis. The effects of shape change on the performance and output power were investigated for regular and irregular wave conditions in ANSYS AQWA at an incident wave frequency of 0.22 Hz (low energy density seas). The optimal resonant buoy was identified employing optimal and sub-optimal modes of the PTO system at external stiffness and damping parameters. Moreover, the performance of resonant buoys in optimal and suboptimal working modes was validated statistically using the F-test for variances of two samples in Origin Pro (2019). The energy conversion efficiencies of Cyl-AS buoy were examined as highest among others, with a maximum of 8.4% and 7.4% rise in optimal and suboptimal PTO modes for regular waves, respectively. For irregular waves, the Cyl-AS buoy resulted in maximum output power of 33.9% higher than the Cyl-HS buoy (reference buoy) with a maximum conversion efficiency of 90%. Finally, the simulation and experimental results for the scaled model were compared for RAO and average power and found a good agreement. The findings of this research agree with the UN-2030 Agenda for Sustainable Development Goals (in particular, SDG-7 and SDG-14 goals) while providing a path towards clean energy and blue economy developments.

Analytical determination of the influence of geometric and material design parameters on the stress and strain fields in non-prismatic components of wind turbines

Non-prismatic beamlike elements have long been used in engineering applications to optimize the performance of structures such as wind turbines, aircraft, and civil bridges, just to mention some examples. Unfortunately, engineering methods and formulas commonly used to analytically evaluate stresses and strains in prismatic beams do not hold and provide incorrect results for non-prismatic geometries. Large displacements and non-uniform material properties further complicate the analytical prediction. In order to determine the state of stress and strain in non-prismatic beamlike elements and its dependence on important design factors (such as taper parameters), a suitable mapping of the shape of such elements and a variational approach are used. The resulting field equations are exploited to derive application-oriented stress-strain formulas. Examples and comparisons with results of non-linear 3D-FEM analyses confirm the effectiveness of the modelling approach and of the new formulas proposed in this work.

Combining advanced 3D printing technologies with origami principles: A new paradigm for the design of functional, durable, and scalable springs

Origami has recently emerged as a platform for building functional engineering systems with versatile characteristics that targeted niche applications. One widely utilized origami-based structure is known as the Kresling origami spring (KOS), which inspired, among many other things, the design of vibration isolators, fluidic muscles, and mechanical bit memory switches. Previous demonstrations of such concepts were carried out using paper-based KOSs, which are suitable for conceptual illustrations but not for implementation in a real environment. In addition to the very low durability resulting from the high plastic deformations at the paper folds; lack of repeatability, and high variation of performance among similar samples are also inevitable. To circumvent these issues, this paper presents a novel approach for the design of a non-paper based KOS, which mimics the qualitative behavior of the paper-based KOS without compromising on durability, repeatability, and functionality. In the new design, each fundamental triangle in the paper-based KOS is replaced by an inner central rigid core and an outer flexible rubber-like frame, which are fabricated out of different visco-elastic materials using advanced 3-D printing technologies. The quasi-static behavior of the fabricated springs was assessed under both compressive and tensile loads. It is shown that KOSs with linear, softening, hardening, mono- and bi-stable restoring force behavior can be fabricated using the proposed design by simple changes to the geometric design parameters, further pointing to the vast range of potential applications of such springs.

Sensitivity analysis of geometrical design parameters on the performance of conical plain bearings for use as main bearings in wind turbines

The failure of a wind turbine’s main bearing causes very high repair costs, as the entire drivetrain has to be disassembled with the help of an external crane. Just the costs for a crane for an offshore turbine can sum up to 200.000€ per day [1]. In contrast, segmented hydrodynamic plain bearings offer the advantage that individual bearing segments can be replaced on the tower without the use of an external crane, which offers great potential for savings in repair costs. However, this application requires new, innovative plain bearing concepts for which the current design guidelines are not applicable. This paper presents a simulation-based design approach for a plain bearing concept with conical sliding surfaces. Such a simulation-based approach with a multi-objective optimization is necessary, because due to the geometric complexity the manual, iterative design process is not efficient. In this paper, a bearing geometry optimized in terms of load distribution and friction losses was developed by applying this approach.

Identification of the geometric design parameters of propeller blades from 3D scanning

This paper presents a new method for the identification of geometric design parameters of ISO 484 class propeller blades from scanned point cloud data. The method can be used for tolerance inspection and in-line measurement of manufactured blades, and for wear assessment and reverse engineering of propellers in service. The geometry of the propeller blades is specified by a set of blade sections stacked radially on concentric cylindrical surfaces. For each of these sections, the chord line and mean camber line is determined, and geometric design parameters such as the pitch, skew, chord length, camber, and thickness distributions are identified. The proposed method is a complete procedure for identifying the design parameters of marine propeller blades from point cloud data, and includes a novel method for the precise identification of the mean camber line based on Voronoi diagrams and Delaunay triangulation. The paper includes validation of the proposed method in experiments where reverse engineering is applied to a propeller blade of the KVLCC2 propeller, and in 3D scanning of a large, high-skew thruster blade where the results were compared to CMM measurements.

Micro-Scale Auxetic Hierarchical Mechanical Metamaterials for Shape Morphing.

Shape morphing and the possibility of having control over mechanical properties via designed deformations have attracted a lot of attention in the materials community and led to a variety of applications with an emphasis on the space industry. However, current materials normally do not allow to have a full control over the deformation pattern and often fail to replicate such behavior at low scales which is essential in flexible electronics. Thus, in this paper, novel 2Dand 3D microscopic hierarchical mechanical metamaterials using mutually-competing substructures within the system that are capable of exhibiting a broad range of the highly unusual auxetic behavior are proposed. Using experiments (3D microprinted polymers) supported by computer simulations, it is shown that such ability can be controlled through geometric design parameters. Finally it is demonstrated that the considered structure can form a composite capable of shape morphing allowing it to deform to a predefined shape.

Aerothermal Characteristics of Surface-Mounted Round-Edged Slit Ribs With Performance Optimization Using Response Surface Methodology

Abstract The author has investigated the aerothermal characteristics of round-edged ribs with a continuous slit. The experiments have been performed by mounting an array of ribs on the bottom wall inside a rectangular duct. Heat transfer characteristics have been measured using liquid crystal thermography (LCT), whereas flow characteristics have been measured using two-dimensional particle image velocimetry (2D-PIV) technique. Experiments have been performed for flow over a rib having ∼20% blockage ratio and 10% open area ratio. Geometrical parameters considered for the study are slit angle (α) and rib pitch-to-height ratio (p/e). Experiments have been performed for three distinct rib configurations having α values, i.e., 0 deg, 5 deg, and 10 deg with different arrangements having p/e values of 5, 10, and 15, at four Reynolds number ranges from 6200 to 12200. The heat transfer results are evaluated by examining the surface and spanwise-averaged distribution of augmented Nusselt number (Nu/Nu0, and Nux¯/Nuo,x¯ respectively). Flow field results are explained within the inter-rib region by examining the time-averaged normalized velocity fields, streamlines, fluctuation statistics, and vorticity distribution. The results show that the flow coming out from the rib geometry significantly affects the heat transfer and flow behavior. Further, the impact of geometrical design parameters (α and p/e) on different performance parameters, i.e., overall averaged augmented Nusselt number (Nu/Nu0¯), friction factor ratio (f/f0), and thermal performance factor (TPF) has been analyzed at all four Reynolds numbers using Response Surface Methodology (RSM). Finally, the desired correlations for the performance parameters have been documented and found in accord with an uncertainty range of ±10%.

Experimental investigations of glued-in rod connections in CLT

The widespread availability of cross-laminated timber (CLT) provides opportunities to extend the use of wood structures beyond low-rise residential construction. Glued-in rods (GiR) are an interesting technical solution for numerous timber structural applications, amongst them, the not yet exploited potential in conjunction with CLT. This paper summarises experimental investigation on the performance of GiR in CLT. Two 5-ply CLT panel thicknesses (139 and 175 mm), two steel rod diameters (dR = 12.7 and 19.1 mm), and five anchorage lengths (la = 6dR, 10dR, 12dR, 14dR and 18dR) were considered in applications parallel and perpendicular to the CLT major strength axis. A total of 220 uni-axial quasi-static monotonic tension tests were conducted. The results, assessed in terms of load-carrying capacity (ranging from 14 kN to 154 kN) and failure modes (plug-shear failure and lamination tear-out), demonstrated the impact of the connection’s geometric design parameters and that steel rods glued into CLT offer an alternative high capacity connection. The results will serve as the benchmark for subsequent numerical modelling, including the determination of joint capacity.

Design and Analysis of Prosthetic Heart Valves and Assessing the Effects of Leaflet Design on the Mechanical Attributes of the Valves

Prosthetic heart valves are commonly used as a treatment for aortic valve deficiencies. The performance of these prosthetic valves should be in accordance with the natural heart valve with respect to opening and closing, blood flow, and vortex formation. These performance parameters depend on the design of leaflets and overall geometrical parameters of the valve. To better understand the effects of leaflet design on the performance of the valve, we have carried out fully coupled fluid–structure interaction analyses of opening and closing of prosthetic heart valves with various leaflet designs. Maximum stress, valve opening, and flow stream pattern are obtained for different valve designs and used to assess the performance of the valves. The results show that the stress and the valve opening depend on the curvature and the inclination of the leaflets. A 3D model is designed based on the obtained results, and a full FSI analysis is performed to assess its performance. The results show that the presented design gives better values for valve opening area and leaflet stresses than that in the published data.

Piezoelectric unimorph and bimorph cantilever configurations: Design guidelines and strain assessment

Multi-stable configurations of piezoelectric harvester are quite successful in achieving the two important goals, the broadband frequency response and large orbit oscillations exhibiting periodic, multi-periodic, and chaotic solutions. However, in the quest of achieving large amplitude broadband frequency response, assessment of induced strain levels considering the limits on the strain in piezoelectric material has received minimal attention. In this context, the investigation presents analytical formulation for the assessment of induced strain and voltage(s) in piezoelectric unimorph and bimorph cantilevers. The formulation quantifies not only the induced voltages in individual piezoelectric layers of a bimorph, but also the equivalent voltages in parallel and series connection modes, respectively. Also, while computing the induced voltage in the first piezoelectric layer, the contribution from the induced voltage of second piezoelectric layer to the acting bending moment is captured in the formulation. The formulations are validated through the experiments and results from the literature. Further, we have applied two practically useful normalization schemes, the - and -normalizations to the analytical expressions. Using the two normalization schemes, influences of variation of substrate and adhesive layer thicknesses, elastic moduli of layers, and substrate-to-composite length fraction are visualized and discussed. Based on the results, summarized guidelines for design and selection of geometric and material parameters are presented, which may also be applicable for other sensing and actuation applications. At last, practically suitable ranges and optimum values for the normalized design variables are proposed.

Ultra-light kirigami lantern chain for superior impact mitigation

Kirigami-based metamaterials are demonstrated to possess peculiar mechanical behaviors via carefully engineered architectures. This paper reports on the comprehensive investigation of a novel kirigami-based lantern chain. We tailor and fabricate the kirigami lanterns using simple paper sheets yet achieve an exceptional impact mitigation capability (orders of magnitude lower transmission compared to various available metamaterials). Detailed experimental and numerical exploration uncovers that the unique folding–unfolding behavior of kirigami lanterns during stress wave propagation yields energy redistribution and storage in different cells. Accordingly, an expanded waveform with decreasing amplitude and oscillating tails is achieved within the 1D chain, largely mitigating the impact. Meanwhile, the plastic deformation of paper materials also contributes to outstanding performances. Based on a validated finite element (FE) model, the governing laws of critical parameters, including impact energy, cell number, petal number, and hinge number, are systematically explored, where we find that the mitigation effect is also satisfactory even at the increased impact energy scenarios. Furthermore, an adaptable design of kirigami chain length and other geometric parameters is exploited to realize highly efficient and controllable mitigation when subjected to specific impact energy. This paper illustrates a new route to designing superior impact mitigation structures with ultra-lightweight materials, offering insights for innovation of next-generation impact protection strategies in the automotive and aerospace industries.

Moisture-sensitive mechanical metamaterials with unusual and re-programmable hygroscopic deformation modes.

Mechanical metamaterials are of great interest due to their counterintuitive deformation under various physical fields. However, the research on metamaterials responding to moisture is still rare and controllable hygroscopic deformation is vital for sensoring, actuating, and stress elimination in a moisture environment. Inspired by the hygroscopic deformation of pinecones, this work studies 2D moisture-sensitive mechanical metamaterials exploiting bi-material curved strips as building blocks by simulations and experiments, which especially demonstrates repeatable programming ability to realize customized unusual hygroscopic deformations. Depending on the structural design of geometrical parameters and material configurations, the metamaterials exhibit a tunable coefficient of hygroscopic expansion from negative to positive, and unusual hygroscopic deformation modes including anisotropic, shearing, gradient, bending, and 3D deformation of 2D structures. Programmable metamaterials of arbitrary hygroscopic deformation are achieved by pixelated design and coding the building blocks. More importantly, the hygroscopic deformation is re-programmable by adopting erasable moisture-proof coatings on specific areas of metamaterials, i.e., it can continuously provide different customized deformation modes in a sample.

Experimental investigation of performance of high-shear atomizer with discrete radial-jet fuel nozzle: mean and dynamic characteristics

The present study focuses on the performance of a novel high-shear atomizer with a discrete radial-jet fuel nozzle to overcome the constraints associated with the simplex-pressure-swirl and duplex-fuel nozzles at the high-end power demand of a gas turbine combustor. The high-shear atomizer consists of multiple inner and outer radial swirlers with interchangeable flare and fuel nozzle. The performance of the atomizer with discrete radial-jet fuel nozzle is elucidated at ALR (mass ratio of air to liquid) 14.1 through variations in geometrical design parameters of the swirl cup. The parameters of interest are the split ratio (γ), relative swirl direction of inner and outer swirler (co- and counter-rotation), flare angle (θ) and flare mixing length (η). Spray characteristics at ALR 4.72, 7.08 and 9.44 are also presented for an atomizer by freezing the geometrical design. The particle image velocimetry diagnostic technique is employed to capture the spray flow field. The non-dimensional radial (W/Df; W, radial width of CTRZ (in mm) and Df, exit diameter of flare (mm)) and axial (L/Df) sizes of the central toroidal recirculation zone and near field swirl number (SN5) of the flow are explored. Further, variations in the droplet size distribution of the atomizer across all the ALR are discussed in detail. The Sauter mean diameter across all the test cases is found to be in the range of 9–30 μm, 15–37 μm, 15–50 μm and 23–75 μm at ALR 14.1, 9.44, 7.08 and 4.72 respectively, which shows good atomization capability of the atomizer with discrete jets. The spatial distribution of the spray volume/mass in an azimuthal plane is examined in the circumferential and radial directions, which shows consistent and excellent azimuthal symmetry of the spray even with a decrease in ALR value. The overall mean and dynamic spray characteristics of the atomizer suggest that high-shear atomizer in combination with a discrete radial-jet fuel nozzle would be a better candidate than an atomizer with a simplex pressure-swirl fuel nozzle in rich-quench-lean concept-based gas turbine combustors.

Geometry and Topology Optimization of Switched Reluctance Machines: A Review

Switched reluctance machines (SRMs) have recently attracted more interest in many applications due to the volatile prices of rare-earth permanent magnets (PMs) used in permanent magnet synchronous machines (PMSMs). They also have rugged construction and can operate at high speeds and high temperatures. However, acoustic noise and high torque ripples, in addition to the relatively low torque density, present significant challenges. Geometry and topology optimization are applied to overcome these challenges and enable SRMs to compete with PMSMs. Key geometric design parameters are optimized to minimize various objective functions within geometry optimization. On the other hand, the material distribution in a particular design space within the machine domain may be optimized using topology optimization. We discuss how these techniques are applied to optimize the geometries and topologies of SRMs to enhance machine performance. As optimizing the machine geometry and material distribution at the design phase is of substantial significance, this work offers a comprehensive literature review on the current state of the art and the possible trends in the optimization techniques of SRMs. The paper also reviews different configurations of SRMs and stochastic and deterministic optimization techniques utilized in optimizing different configurations of the machine.