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This study investigated the role of mobile applications as aids in solving systems of linear equations with two variables through the graphical method. The use of mobile applications was examined in a group of primary and lower school students to evaluate their effectiveness in learning mathematics and improving their skills in solving systems of linear equations. The main goal of this scientific paper is to investigate and evaluate the role of mobile applications as aids in solving systems of linear equations, involving students in the research process. The research method included a mixed-methods design including quantitative analysis of mobile application results and qualitative analysis of students' experiences and opinions. Data collection was conducted through individual interviews and classroom observations. The results show that the use of these technological tools has a positive impact on the involvement of students, increasing the interest and efficiency of learning. The findings also highlight challenges and suggestions for improving the use of mobile applications in the mathematics teaching context. This study contributes to the understanding of the use of mobile technology for the development of mathematical skills at the lower secondary school level. [ABSTRACT FROM AUTHOR]

Unit distributions, exhibiting inherent symmetrical properties, have been extensively studied across various fields. A significant challenge in these studies, particularly evident in parameter estimations, is the existence and uniqueness of estimators. Often, it is challenging to demonstrate the existence of a unique estimator. The major issue with maximum likelihood and other estimator-finding methods that use iterative methods is that they need an initial value to reach the solution. This dependency on initial values can lead to local extremes that fail to represent the global extremities, highlighting a lack of symmetry in solution robustness. This study applies a very simple, and unique, estimation method for unit Weibull and unit Burr XII distributions that both attain the global maximum value. Therefore, we can conclude that the findings from the obtained propositions demonstrate that both the maximum likelihood and graphical methods are symmetrically similar. In addition, three real-world data applications are made to show that the method works efficiently. [ABSTRACT FROM AUTHOR]

Stress and deformation analysis of a cavity in an infinite/finite medium is a fundamental applied mechanics problem of interest in multiple physics and engineering disciplines. This paper develops a complete semianalytical solution for the cylindrical cavity expansion in nonassociated Mohr–Coulomb materials, by using the graphical approach and Lagrangian formulation of the cavity boundary value problem (through tracing the responses of a single material point at the cavity wall). The novelty of the new solution framework lies not only in the relaxation of the stringent intermediacy assumption for the vertical stress as usually adopted in the previous analyses, but also in the comprehensive consideration of nonhydrostatic initial stress conditions via arbitrary values of K0 (the coefficient of earth pressure at rest defined as the ratio between the horizontal and vertical initial stresses). The essence of the so-called graphical method, i.e., the unique geometrical analysis and tracking of the deviatoric stress trajectory, is fulfilled by leveraging the deformation requirement that during cavity expansion the progressive development of the radial and tangential strains must maintain to be compressive and tensile, respectively. With the incorporation of the radial equilibrium condition, the problem is formulated to solve a single first-order differential equation for the internal cavity pressure with respect to a pivotal auxiliary variable, for all the distinct scenarios of K0 being covered. Some selected results are presented for the calculated cavity pressure-expansion curve and limit cavity pressure through an example analysis. The definitive semianalytical solution proposed will be not only substantially advancing the current state of knowledge on the fundamental cavity expansion theory, but also able to serve as a unique benchmark for truly verifying the correctness and capability of the classical cornered Mohr–Coulomb constitutive model built in commercial finite element programs. [ABSTRACT FROM AUTHOR]

Single-point incremental forming (SPIF) has emerged as a cost-effective and rapid manufacturing method, especially suitable for small-batch production due to its minimal reliance on molds, swift production, and affordability. Nonetheless, SPIF's effectiveness is closely tied to the specific characteristics of the employed sheet materials and the intricacies of the desired shapes. Immediate experimentation with SPIF often leads to numerous product defects. Therefore, the pre-emptive use of numerical simulations to predict these defects is of paramount importance. In this study, we focus on the critical role of the forming limit curve (FLC) in SPIF simulations, specifically in anticipating product fractures. To facilitate this, we first construct the forming limit curve for Al1050 sheet material, leveraging the modified maximum force criterion (MMFC). This criterion, well-established in the field, derives FLCs based on the theory of hardening laws in sheet metal yield curves. In conjunction with the MMFC, we introduce a graphical approach that simplifies the prediction of forming limit curves at fracture (FLCF). Within the context of the SPIF method, FLCF is established through both uniaxial tensile deformation (U.T) and simultaneous uniform tensile deformation in bi-axial tensile (B.T). Subsequently, the FLCF predictions are applied in simulations and experiments focused on forming truncated cone parts. Notably, a substantial deviation in fracture height, amounting to 15.97%, is observed between simulated and experimental samples. To enhance FLCF prediction accuracy in SPIF, we propose a novel method based on simulations of truncated cone parts with variable tool radii. A FLCF is then constructed by determining major/minor strains in simulated samples. To ascertain the validity of this enhanced FLCF model, our study includes simulations and tests of truncated cone samples with varying wall angles, revealing a substantial alignment in fracture height between corresponding samples. This research contributes to the advancement of SPIF by enhancing our ability to predict and mitigate product defects, ultimately expanding the applicability of SPIF in diverse industrial contexts. [ABSTRACT FROM AUTHOR]

Ellipsometrically obtained spectral dependences of ordinary αxy and extra-ordinary αz extinction/attenuation coefficients within the spectral range λ = 300…980 nm of uniaxially anisotropic polytetrafluoroethylene (PTFE) films were analyzed. We considered the capabilities and specific features of the graphical representation technique for determining the contribution of Rayleigh scattering and Urbach absorption to light attenuation in the spectral range beyond fundamental absorption. It has been shown that the graphical approach enables to estimate these contributions qualitatively, semi-quantitatively or quantitatively, depending on the situation. The conclusions made using the analysis of graphical representation are confirmed by numerical solution of the inverse problem via simulation of the αxy (λ), αz (λ) experimental dependences within the framework of a best-fit procedure. Being based on both of these approaches, we have ascertained that, in the as-prepared PTFE films, the so-called anomalous light scattering (ALS) with the spectral dependence of scattering coefficient αs ≈ as λ–p (p > 4) takes place. Transformation of scattering from ALS to the Rayleigh one with p ≅ 4 due to annealing is accompanied by an increase of Urbach (subband) absorption. Both of these factors cause narrowing the dynamic range of extinction coefficient values. Both scattering and absorption coefficients are higher for the component of light polarized along the normal to the substrate as compared to the component polarized in parallel to it. The relationship between observed behavior of the scattering and absorption coefficients and the film structure has been discussed. [ABSTRACT FROM AUTHOR]

The Bayesian approach is applied to estimation of the Weibull-power law process (WPLP) parameters as an alternative to the maximum likelihood (ML) method in the case when the number of events is small. For the process model considered we propose to apply the independent Jeffreys prior distribution and we argue that this is a useful choice. Comparisons were also made between the accuracy of the estimators obtained and those obtained by using other priors—informative and weakly informative. The investigations show that the Bayesian approach in many cases of a fairly broad collection of WPLP models can lead to the Bayes estimators that are more accurate than the corresponding ML ones, when the number of events is small. The problem of fitting the WPLP models, based on ML and Bayes estimators, to some real data is also considered. It is shown that the TTT-concept, used in the reliability theory, is not fully useful for the WPLP models, and it may be so for some other trend-renewal processes. In order to assess the accuracy of the fitting to the real data considered, two other graphical methods are introduced. [ABSTRACT FROM AUTHOR]

We propose a powerful graphical method for evaluating the natural complex frequencies and amplitudes of the layered structures for their electromagnetic characterization. Its advantage is to show a pattern of the location of the natural complex frequencies so that it would be possible to examine how they can move for a possible error in the measurement system. The method is validated by a two-layered structure by comparing the natural complex frequencies and amplitudes computed by the proposed method and the inverse Fourier transform. It has been applied to monitor the effect of noise in a measurement system. [ABSTRACT FROM AUTHOR]

Actuator rate limit phenomenon is ubiquitous in control systems, but it has always been neglected in practical engineering. Especially, few papers are published to investigate the system identification while considering the rate limit. Step function is commonly used in parameter estimation and its first‐order derivative at the step time goes to infinity, which is not affordable by real actuators. As a result, the rate limit slows down the system response speed, misleads the parameter identification, and subsequently affects the controller design and deteriorates the control performance. This study proposes both graphical method and curve fitting method to identify the first‐order plus time‐delay (FOPTD) systems with consideration of the actuator rate limit effect whose limit value is unknown. Quantitative analyses of the parameter mismatch in the traditional FOPTD model and parameter sensitivity analyses are also carried out. Both simulation results and experimental results have shown the necessity and feasibility of defining a new model structure which includes the rate limit value. [ABSTRACT FROM AUTHOR]

In order to investigate the interaction of genotype × trait and relationships among agronomic traits on 12 maize hybrids, an experiment was conducted in a randomized complete block design (RCBD) with three replicates in four regions of Karaj, Birjand, Shiraz, and Arak. Results of analysis of variance indicated that most of the genotypes were significantly different in terms of agronomic traits. Mean comparison by Duncan's method showed that KSC705 genotype was more favorable than other genotypes in all studied regions. SC604 genotype in Birjand and Karaj regions and KSC707 genotype in Shiraz region have higher rank than other genotypes. Correlation analysis was used to investigate the relationships between traits. In most of the studied regions, traits of number of grains in row and number of rows per ear were positively and significantly correlated with grain width and grain weight with grain yield. Graphical analysis was used to further investigate. Genotypes–trait interaction graph explained 59.27%, 61.22%, 59.17%, and 61.95% of total variance in Karaj, Birjand, Shiraz, and Arak, respectively. Based on the multivariate graph, KSC705, KSC706, and SC647 genotypes were identified as superior genotypes in all studied regions and KSC400 genotype did not show much response to change in traits. Correlation between grain width and number of rows in ear, plant height and grain length, one thousand grain weight and grain thickness, and ear diameter with number of grains in row was positive and significant. The results of classification graph of genotypes also divided the cultivars in to three groups as follows: KSC703, KSC400, and KSC706 genotypes in the first group; DC370, SC604, and SC301 in the second group; and KSC260, KSC704, KSC707, and SC301 in the third group. [ABSTRACT FROM AUTHOR]

The AE AOD – ΔAE AOD grid proposed by Gobbi et al. (2007) is a graphical method used to visually represent the spectral characterization of aerosol optical depth (AOD), i.e. Angström exponent (AE) and its curvature, in order to infer the fine mode contribution (η) to the total AOD and the size of the fine mode aerosol particles. Perrone et al. (2014) applied this method for the wavelengths widely used in lidar measurements. However, in neither case does the method allow for a direct relationship between η and the fine mode fraction contribution to the total aerosol population. Some discussions are made regarding the effect of shape and composition to the classical AE-ΔAE plot. The potential use of particle backscatter measurements, widely used in aerosol characterization methods together with extinction measurements, is also discussed in the AE-ΔAE grid context. A modification is proposed that yields the submicron contribution to the total volume concentration by using particle extinction data, and a comparison to experimental measurements is made. Our results indicate that the use of a modified AE-ΔAE grid plot to directly obtain submicrometric and micrometric mode fraction to the total aerosol population is feasible if a volume-based bimodal particle size distribution is used instead of a number-based one. • AE AOD – ΔAE AOD graphical grid plots (Gobbi) yield fine-mode contribution to AOD. • A modified Gobbi plot is proposed that links fine-mode volume contribution to AOD. • The use of particle backscatter measurements is discussed in the AE-ΔAE grid context. [ABSTRACT FROM AUTHOR]

Currently, informative graphics has attracted considerable attention for its efficient and effective methods of communication. The ways in which people receive information strongly influence their ability not only to comprehend the information but also to capitalize on the purported benefits of the information. Informationdesign approaches can facilitate the creation of many good-quality designs. By understanding both the history of information design and pertinent case studies, we can familiarize ourselves with information-design methods and applications. In this article, I discuss the evolution and various forms of informative graphics on the basis of historical, content-oriented, and phenomenological analyses. I investigate visual representations' roles and identify the strengths and deficiencies of visual communication for information design. Historical evidence--such as Playfair's graphic charts and his method, Winderlich's clinical graphics, Nightingale's statistical graphs, and Snow's dot maps--show that appropriate visual formats can depict data and that these depictions can demonstrate effects over time. The graphical method can also aid in the measurement of small-time intervals between biological effects. Multiple variables enhance the exploratory power of graphics in relation to analysis and discovery. Narrative graphics associate the spatial dimension with time-series displays to depict space and time. Although many disciplines acknowledge "the importance of communication,"the general public in Taiwan has only recently begun to acknowledge the importance of informative graphics. We should reflect now and then on the evolution and various forms of informative graphics. [ABSTRACT FROM AUTHOR]

The classical method (namely inclining experiment) has been used to estimate the vertical center of gravity (VCG or more often KG) of ships for many years. This method is based on the assumption that the metacenter is unchanged in the calculation of KG when the vessel is heeled. However, ships built today have knuckles, chines, dead-rise which may give rise to excessive change in the water-plane. The location of the metacenter is changed on these vessels when heeled. Therefore, determination of the vertical center of gravity may be somewhat erroneous. In this study, three different methods based on the assumption of unchanged metacenter have been examined. Employing the Graphical method, Polar method and Generalized method, the KG values of all vessels can be calculated without any dependence on the metacenter. The three methods mentioned in this study were studied and applied on ten different ships. Furthermore, the results from the classical method compared with those obtained from the recently developed methods. Based on this comparison, it is observed that the new methods developed have similar results to the classical method. Therefore, these methods may be a good alternative to the inclining experiment in the future. Moreover, uncertainty analyses have been performed for the results obtained from the classical method just to realize if there are any critical GM values within the margin of error. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a graphical approach to assess the detectability of multiple simultaneous faults in mechanical systems such as Air Handling Units (AHUs). Symptoms of multiple simultaneous faults can cancel each other out, resulting in no indication of abnormality and rendering these faults undetectable when the measurements collected from AHUs are processed. Still, such undetectable faults can lead to significant energy inefficiency and economic loss. We present a method to assess the detectability of a given set of faults provided the causal relations among the variables and the sensor configuration in the system. Fault detectability assessment informs decision makers about possible risk scenarios the system is exposed to and enables them to design/modify the system to reduce this exposure, e.g. by adding extra sensors where necessary. Our approach first constructs a graphical representation of a given system so that the causal relations among the variables and whether they are sensed can be visually observed, which can help predict until where a fault symptom can propagate. Then, our approach examines a given set of faults to check whether it is possible for that set to be detected by the given set of available sensors. We illustrate the application of our approach to an operational AHU and classify which sets of faults are detectable and which are not. We compare our approach with alternative methods and show that one of its benefits is the capability of handling systems with unpredictable input variables. [ABSTRACT FROM AUTHOR]

The ion mobility and ion density are key physical parameters in research of ion flow field of high‐voltage DC (HVDC) transmission lines. The Gerdien tube is one of the practical tools that can be utilised in situ measurement of ion mobility and ion density of coronated lines. The mobility spectrum, connecting the ion mobility and ion density, is an effective approach in analysis of the characteristics of corona ions and the effects of environmental factors on them. In previous studies, single measurement‐electrode Gerdien tube is frequently used to get the mobility of one single ion via graphical method or the total ion density when the tube is operating as a counter. To enable it to obtain the ion mobility spectrum, a method is devised by the analysis of graphical method and the transition phenomenon in current–voltage characteristics of the tube. Furthermore, the method is applied to the raw data of current–voltage characteristics published in the literatures. The ion mobility spectra are obtained and compared with those having been reported. By doing this, the method is validated. This new approach makes applications of Gerdien tubes more advantages in experimental researches of ion flow field of HVDC transmission lines. [ABSTRACT FROM AUTHOR]

For metallic or composite materials, the judicious choice of cutting conditions depends on several factors that may be of such objectives (time, cost of production, material removal rate, etc.) or constraints (cutting force, temperature in the machining area, consumed power, etc.). The quality of the results depends on the optimization method and the efficiency of the algorithm involved. In this paper, graphical and particle swarm optimization (PSO) methods are proposed. They aim to determine the optimal cutting conditions (cutting speed and feed per tooth) in slotting of multidirectional carbon fiber reinforced plastic laminate (CFRP), referenced G803/914, with three knurled tools having different geometries. The experiences that led to the measures of roughness, temperature, cutting efforts, and consumed power are made in the same working conditions with cutting speed ranging from 80 to 200 m/min and feed per tooth from 0.008 to 0.060 mm/rev/tooth. The results illustrate that for the graphical method, the optimum cutting speed depends on the performance “maximum total removal rate” and is the same for all the studied knurled tools while optimum feed per tooth depends on the “roughness” performance: its value depends on the tool geometry. For the PSO technique, optimum cutting speed and feed per tooth values are variable and depend on the tool geometry. [ABSTRACT FROM AUTHOR]

In this paper, a new deployable mechanism of ring and frustum type is developed for aviation and aerospace applications. Considering the ring and frustum type, the truss deduction method is utilized to determine the configuration to implement the centripetal (axial and radial) movement. A graphical method-based approach is presented to analyze the DOF of the designed mechanism which is verified to be one both by using a virtual prototype and a physical prototype. Scissors mechanism is utilized to achieve the required high folding and unfolding ratio and to guarantee the internal space of the mechanism is not occupied. Except the inherent characteristic of a deployable mechanism, the proposed mechanism has enough kinetic energy to overcome the gravity to jump off the ground when it stretches thoroughly. Considering the required kinetic energy, springs are used as the driver to store enough energy. The dynamic model of the mechanism is put forward to identify the stiffness of the driving spring and the mass of each connecting rod and the upper and lower platforms. The virtual prototype simulation and the physical prototype both validate the function of the new design and the feasibility of the proposed analytical approaches. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive delay‐dependent stability analysis of a micro‐grid system with constant communication delays. First, an exact method that takes into account both gain and phase margins (GPMs) is proposed to determine stability delay margins in terms of system and controller parameters. The method implements an elimination procedure to transform transcendental characteristic equation into a standard polynomial of the crossing frequency. The real roots of this new standard polynomial exactly match with the purely imaginary roots (crossing frequencies) of the original characteristic equation with transcendental terms. Second, an effective and simple graphical method is implemented to compute all stabilising proportional integral (PI) controller gains for a given time delay. The approach is based on extracting stability region and the stability boundary locus in the PI controller parameter space having user defined GPMs, and relative stability. The time‐domain simulation studies indicate that the proposed schemes give better desired dynamic performance as compared with the recently developed schemes for micro‐grid with communication delays. [ABSTRACT FROM AUTHOR]

This paper proposes a method for determining a development of the rotation surface, which is the rotation of hypocycloids with 4 branches. It has been chosen a four-cusped hypocycloid called astroid, because, due to its aesthetic shape, this could be used in industrial design. This paper proposes getting the development for a rotation surface generated by astroid. It is applied the graphical method of descriptive geometry by analogy with the developed by the sphere. This approximate graphical method is applied relatively simple and can be used when a high precision is not required for the product. [ABSTRACT FROM AUTHOR]

Industrialized closing systems appear as rational solutions in steel-structured construction. These closing systems, consisting of multi-layered panels, have been applied in projects where it is intended to obtain a high sound transmission loss without raising the cost and without using a lot of mass. However, acoustic isolation depends on several factors, including the type of connection between the panels, requiring a preliminary study of the acoustic performance of the closing system to prevent future interventions. This paper uses a simplified graphical method to evaluate the influence of the type of connection (line-line, line-punctual or punctual-punctual) of industrialized closing panels on the estimation of the sound transmission loss that occurs across the wall constituted by these panels. The panels are combined, forming multi-layered closings interleaved by a layer of air, either without or with a sound-absorbing material between them. The results show that it is necessary to check the effectiveness of each type of fastening of the closing systems because, for example, for the frequency range between 500 and 2,000 Hz, the sound transmission loss of a closing system consisting of cementitious plate with glass wool and line-punctual and punctual-punctual connections exceeds in 6.25% the sound transmission loss of the same system with line-line fastening. For a system composed of expanded polystyrene with glass wool, the sound transmission loss provided by line-line fastening exceeds in 7.0% the sound transmission loss of the same closing system with line-punctual and punctual-punctual fastenings. [ABSTRACT FROM AUTHOR]

Significant part of the world cultural heritage is represented by masonry buildings. Many of them are characterised by a complex architecture like as the religious buildings and need to be preserved, from a structural point of view, especially in high seismic risk areas. The recent earthquakes showed that the Historical and Monumental buildings are often characterised by high seismic vulnerability. The lowest seismic performances are associated with the presence of thrusting elements like as arches and vaults. In this background, the numerical analyses and experimental simulations provide important information about the structural behaviour of such elements. The structural behaviour of curved elements can be complex to simulate and to predict exclusively by numerical analyses. Indeed, the experimental tests can provide an efficient contribution to the calibration and interpretation of the numerical models. The present work focuses on a particular typology of vaults generally used as roofs in religious buildings. These vaults typically do not include any backfill and are slender. These typologies of masonry vaults cannot be analysed with classical approaches where no-tension is assumed. In fact, the tensile strength must be included in order to assess the seismic capacity of these masonry elements. A simplified analytical model, which includes the tensile strength, was proposed. Validation of the analytical model is provided by comparing predictions of the load capacity and the failure mode with those obtained from previous shaking table test series on two full scale masonry vaults. The proposed method represents a useful modelling tool in order to design dynamic tests on masonry vaults and to assess their vulnerability. [ABSTRACT FROM AUTHOR]

In this study, wind energy potential of Osmaniye was statistically analyzed which based on an h ourly m easured wind s peed d ata in 2013. Today, developing countries like our country especially member states of the European Union have turned to renewable energy sources in order to meet the rapidly growing need for energy. Wind power distribution plays a crucial role in producing electricity from wind power and building wind turbines. The Weibull and Rayleigh Distributions were used to investigate the region's wind energy potential. The preresearch results show that the wind energy potential in Osmaniye is statistically suitable for electricity production. We have collected the data on the 2013 hourlymeasured wind speed from Osmaniye Meteorology Station of the General Directorate of State M eteorology. We have used the 2013 wind speed values of Osmaniye for inquiring the accordance of blowing hours with the Weibull and Rayleigh Distribution function. The adaptation of blowing time of wind speed which was measured for one year in 2013 was investigated at the Weibull and Rayleigh distribution function at Osmaniye region. Graphical and Moment method were used to calculate the parameters of the Weibull and Rayleigh distribution. The shape 'k' and scale parameter 'c' of Graphical method were calculated 1.0046 - 1.7744 (m/s), respectively. The shape 'k' and scale parameter 'c' of Moment method were calculated 1.6394- 2.5391 (m / s), respectively. Consequently, the value obtained by Weibull model, according to the value obtained by Rayleigh model gave better results. [ABSTRACT FROM AUTHOR]

Chemical absorption method plays an important role in the process of CO 2 separation. One major problem for chemical absorption is huge energy consumption, which is affected by the performance of absorbents. Developing a type of absorbent with high absorption capacity and low regenerative energy consumption is a research topic that attracts attention. The combination of two or more amines is one way to develop new solvents. However, the change of amine liquid ratio can cause a series of complex nonlinear changes in absorption capacity, absorption heat, the heat of vaporisation and sensible heat. It is of interest to visualise the amine solution mixing ratio optimisation to help reduce the energy consumption and increase the absorption capacity. Derivative analysis of standardised vs variables diagram (DSVD), a kind of graphical method based on maximum benefit and minimum consumption, is proposed to determine the optimal mixing ratio of binary amine solution. This novel approach helps to visualise what kind of amines are not suitable for compounding, what kind of amines have the best compounding ratio, and how to determine the optimal compounding ratio. The optimal mixing ratio of the Methyldiethanolamine (MDEA) - Piperazine (PZ) system and MDEA - Monoethanolamine (MEA) were optimised by this method. The optimal ratio of MDEA - PZ and MDEA - MEA are 0.6 (PZ: MDEA = 0.6:0.4, wt.%) and 0.8 (MEA: MDEA = 0.8:0.2, wt.%). • Derivative analysis of standardised vs variables diagram (DSVD) is proposed. • A new method to determine the optimal mixing ratio of binary amine solution. • Multi-objective graphic solution based on benefit and consumption. • The mixing ratio of MDEA + MEA system and MDEA + PZ system was optimised. [ABSTRACT FROM AUTHOR]

The peculiarity of lidar systems is to provide profiles of optical properties of the atmosphere. The use of specific wavelengths and the selection of different kinds of backscattering (elastic, Raman, polarisation selective) permit to obtain information about suspended particles (aerosols). The authors show here a case study in which particle signals are detected from the boundary layer up to the stratosphere. Information on the size distribution of the different layers can be obtained, using a graphical method relying on the spectral dependence of aerosol extinction. The authors apply this method, for the first time to their knowledge, to stratospheric aerosol. [ABSTRACT FROM AUTHOR]

Highlights: [•] A graphical integration method is developed for work exchange network. [•] Linearly approximated sink auxiliary lines are proposed. [•] Five matching rules are proposed for identifying the feasible match. [•] The proposed method can be applied to target the maximum energy recovery. [Copyright &y& Elsevier]

Highlights: [•] Heat integration of heat exchanger networks featuring batch streams is firstly considered. [•] A new method based on the heat duty–time (Q–t) diagram is proposed. [•] Energy targeting and network design can be obtained easily. [•] Both direct and indirect heat integration of batch streams are considered. [Copyright &y& Elsevier]

Several international institutions have defined background or baseline levels to assess heavy metal concentrations on marine sediments in order to use these values as a reference for sediment quality indices. This criterion for marine sediment quality is applied to evaluate the potential risk of pollutants in aquatic ecosystems. However, those values were established using samples collected in large areas which present specific geochemical conditions. Then there may be a lack of accuracy in the results when using these parameters in other areas. In this context, 15 sediment cores (8 cm diameter; 2 m length) were recovered along the 400 km Asturian coastline, which is an area with representative lithological conditions for the Bay of Biscay, to determine more precise baseline levels for marine sediments from the Bay of Biscay. An evaluation of statistical and empirical methods was done to determine which method delivers the best results. Statistical methods such as mean±2SD and median±2* Median Absolut Deviation (MAD) are strongly influenced by outliers and data distributions which make these approaches less robust. Graphic techniques such as Cumulative Distribution Function (CDF) avoid the problems that asymmetrical data distributions may cause but introduce a certain level of subjectivity in the results due to the baseline values obtained depending on the researcher's experience. Finally, the Probability Curve (CP) method solves issues which may occur when using other techniques and allows one to establish baseline levels based on different percentiles. Regarding the features of the data analysed in this study, the baselines obtained via the CP method with the 95th percentile appear to be the most accurate for the Bay of Biscay. A wide variation has been found between the new baseline values and other international and national levels. Disparity between those levels and the baselines obtained in this study can be generated by granulometric and geological factors. The notable increase in Hg baseline values with respect to OSPAR Background Concentration values (BCs) (0.05 μg g−1 and 0.6 μg g−1 respectively) and the huge different with CEDEX levels and new threshold levels (0.35 μg g−1 and 1.2 μg g−1 respectively) emphasised the relevance of defining specific baselines and threshold levels, as the ones obtained in this study, not only to obtain more precise criteria for marine sediment quality to be used in environmental assessments, but also to propose new threshold levels for the evaluation of dredged material before dumping into ocean sites. • 95th percentile on Probability Curve method determine the most accurate baselines. • Regional geological diversity causes baselines very different from OSPAR. • Natural Hg concentrations were twelve times higher than the OSPAR level. • Recalculated Hg Spanish sediment management level was 3 times the actual value. • Specific baselines and threshold levels are needed to get accurate assessments. [ABSTRACT FROM AUTHOR]

This paper approaches the issue of profiling gear hob bounded by a cylindrical helical surface with constant pitch, reciprocally enveloping with an ordered surfaces curl. The process kinematics of generation reproduces the 3D gear between the worm and the wheel. This gear has crossing axes and it is used for the profiling of the primary peripheral surface of the gear hub in the intermediary surface method (the common rack-gear of the surfaces curl to be generated and the primary peripheral surface of the gear hob). An algorithm in the CATIA design environment is presented, based onto an original method for the determination of the reference rack-gear form—the rack-gear reciprocally enveloping with the surfaces curl, using the principle of the cylindrical helical motion decomposition in translation and rotation motions. Graphical and analytical profiling examples are presented for the gear hob for generation of a parallel spline shaft and for the generation of a toothed wheel with involute teeth. Solutions for the interference problems, problems due to the singular points onto the profiles, are presented. [ABSTRACT FROM AUTHOR]

In this paper, we propose a method based on the surfaces enveloping theory developed as a vertical application in the CATIA graphical design environment. This method is created for profiling tools intended to generate cylindrical helical surfaces with constant pitch. The devised method is applicable for the profiling of disc tools which are bounded by a primary peripheral surface of revolution. A few examples for the determination of the tool's 3D primary peripheral surface are presented such as helical flutes of cutting tools, worms with wide pitches, and gear involute flanks. The results are presented in both graphical and tabular form for completeness. Screen snapshots of the CATIA-based vertical application are also shown. [ABSTRACT FROM AUTHOR]

This paper presents an optimal scheme of excitation capacitor to decrease the capacity of static excitation controller (SEC) for dual stator-winding induction generator (DWIG) system applied in wind power generation. The investigations into reactive excitation power released by the excitation capacitor and SEC illustrate that the optimal excitation capacitor is not only related to generator parameters, speed range, and load, but also affected by wind turbine power curve. Based on the objective of minimizing the capacity of SEC, several methods are employed here to select an appropriate excitation capacitor. Through the analysis of DWIG control mechanism and model of SEC in the stator-voltage-orientation synchronous d– q frame, a decoupling control strategy using the space vector modulation is obtained. On the basis of this, the simulation and experimental works from the prototype of 18-kW six/three-phase DWIG wind power system are carried out to verify the optimal scheme. The results demonstrate the correctness and effectiveness of this optimization scheme. [ABSTRACT FROM PUBLISHER]

Abstract: Increase in refining demand and tighter environmental regulations have led to sharp increases in hydrogen consumption of oil refineries. Hydrogen conservation and effective use are of interest to refineries whose operations and profitability are constrained by hydrogen. Purification is widely used in hydrogen networks of refineries to reduce hydrogen production load. To minimize hydrogen utility consumption, it is necessary to optimize the hydrogen network with purification as a whole. In this paper, for hydrogen purification process, a triangle rule (which can be generalized to polygon rule) is proposed for graphical representation of its mass balance. The proposed procedure treats the product concentration and recovery rate of the purification process as adjustable parameters. An ensuing graphical method is developed for targeting the pinch point and minimum utility consumption of the hydrogen system with purification reuse. This graphical method can be used for any purification devices and in systems with any utility concentration. A refinery case is studied to demonstrate the optimization method. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a novel systematic model-based methodology for performing integrated process design and controller design (IPDC) for chemical processes is presented. The methodology uses a decomposition method to solve the IPDC typically formulated as a mathematical programming (optimization with constraints) problem. Accordingly the optimization problem is decomposed into four sub-problems: (i) pre-analysis, (ii) design analysis, (iii) controller design analysis, and (iv) final selection and verification, which are relatively easier to solve. The methodology makes use of thermodynamic-process insights and the reverse design approach to arrive at the final process design–controller design decisions. The developed methodology is illustrated through the design of: (a) a single reactor, (b) a single separator, and (c) a reactor–separator-recycle system and shown to provide effective solutions that satisfy design, control and cost criteria. The advantage of the proposed methodology is that it is systematic, makes use of thermodynamic-process knowledge and provides valuable insights to the solution of IPDC problems in chemical engineering practice. [Copyright &y& Elsevier]

Abstract: A pulse test is one of the simplest identification tests. Here a simple graphical method that uses the integral of pulse response and identifies a first order plus time delay (FOPTD) model is proposed. It can be effectively applied to noisy pulse responses because the integral of the pulse response is used. It can also be applied to noisy step responses, improving the previously developed area method. [Copyright &y& Elsevier]

Abstract: Prediction of maximum load bearing capacity and crack growth for ductile materials using existing models like J-R curve approach has the problem of transferability and the use of micro-mechanical model (e.g. Gurson Tvergaard, and Needleman [Tvergaard V, Needleman A. Analysis of cup cone fracture in a round tensile bar. Acta Metall 1984;32:157–169]) are limited by the requirements of the huge computation time and large numbers of critical metallurgical parameters as input to analysis. Marie and Chapuliot [Marie S, Chapuliot S. Ductile tearing simulation based on local energy criterion. Fatigue Fract Engng Mater Struct 1998;21:215–227] of CEA, France, proposed a simple but convenient ductile crack growth model using critical fracture energy (G fr) for crack growth and J i for initiation, both of which are material parameters. They also proposed several schemes, namely, graphical and slope of modified plastic J-integral vs crack growth, J M-pl − Δa methods for the evaluation of the value of G fr from specimens as well as from components. In all these methods the role of non-crack displacement in the crack growth process was not considered. The necessary modifications due to non-crack displacement in the above methods to evaluate the values of G fr was studied and published [Acharyya S, Dhar S, Chattopadhyay J. (2003). The effect of non-crack component on Critical fracture energy on ductile material. Int J Pressure Vessels Piping 2004;81:345–353] by the authors earlier. In this paper, the modified methods and formulation have been applied to evaluate the values of G fr from experimental and FE simulated results for compact tensile (CT), three point bend (TPB) specimens and also from components like pipes and elbows. Then statistical estimation is done from these G fr values to assess whether G fr can be accepted as constant value material parameter. Finally, the mean value of G fr obtained from statistical computation is used as material constant along with crack initiation toughness parameter (J i)SZW to consider crack growth for FE simulation of load vs load-line–displacement (LLD) and load vs crack growth curves for different specimens and components. Finite element simulated results are compared with the experimental results and good matching between the two for several components are found and maximum error in prediction of maximum load is found to be within 12%. [Copyright &y& Elsevier]

Water system integration with regeneration recycling can reduce freshwater consumption and wastewater discharge to the maximum extent. In this paper, by analyzing the limiting composite curve of a single-contaminant water system, a method is proposed to construct the optimal water supply line for regeneration recycling. Accordingly the targets for regeneration recycling water systems are obtained. The targets in sequence are the minimum freshwater consumption (the minimum wastewater discharge), the minimum regenerated water flowrate, and the optimal regeneration concentration. The post-regeneration concentration is taken to be fixed in the sequential targeting procedure. The interactions of these targets are analyzed, and formulas for calculating these targets are proposed. The results show that for a single-contaminant regeneration recycling water system, the minimum freshwater consumption is determined by the shape of the limiting composite curve below the post-regeneration concentration. The optimal regeneration concentration is defined as the minimum regeneration concentration at the minimum freshwater consumption and the corresponding minimum regenerated water flowrate. The minimum regenerated water flowrate and the optimal regeneration concentration are both related to the geometrical features of the limiting composite curve of the water-using system and to the post-regeneration concentration. The optimal regeneration concentration has no direct relationship with the pinch concentration. [Copyright &y& Elsevier]

In areas of varying geology, it is difficult to infer water quality from specific conductance or electrical conductivity (EC) data without an understanding of the expected range of EC values based on local bedrock composition. This paper describes a user-friendly graphical screening method that addresses this issue by plotting the EC against concurrent alkalinity data, which correlates well with the presence of carbonate bedrock under natural conditions, and thus serves as an index of bedrock type. The upper limit of EC vs. alkalinity expected in a stream is determined using regional groundwater quality data, based on the assumption that stream chemistry reflects groundwater under baseflow conditions. Stream samples with EC/alkalinity values that consistently plot above this limit are considered impacted by anthropogenic sources. The effect of dilution and runoff on the EC vs. alkalinity plot of stream samples is considered using a simple baseflow/storm runoff-mixing model. The graphical method''s utility as a screening tool is demonstrated by application to stream chemistry data from watersheds of southeastern Pennsylvania and northwestern New Jersey conductivity in several distinct geologic settings; however the method is general and widely applicable to watersheds in humid temperate regions. Its use is intended for watershed stewards of both professional and nonprofessional qualification. [Copyright &y& Elsevier]

Recently, Marie and Chapuliot have described ductile failure in terms of fracture energy which is associated with the local plasticity surrounding the crack tip. They introduced critical fracture energy, Gfr, as a new energy release term related to crack growth and also claimed that Gfr is a material property. They also proposed several schemes for the determination of the value of Gfr from specimens as well as from components. In all these methods the role of non-crack displacement in the crack growth process has not been considered. For the specimens or the components for which non-crack displacements are significant the proposed methods have some limitations in their application. In this paper an attempt has been taken to model the ductile crack growth phenomenon with the same approach of Gfr considering the effect of non-crack displacement during crack growth. The necessary modifications in a graphical method for determination of Gfr have been suggested. The expression for Ernest''s JM-pl from which Gfr is calculated is also modified. The values of Gfr have been determined using the modified schemes for CT specimens and pipes with circumferential cracks and checked for whether Gfr is an intrinsic material property. [Copyright &y& Elsevier]

In this research, a stable environmental isotope study was carried out from an analysis of water samples collected from rainfall, runoff (total discharge), springs (subsurface flows) and wells (groundwater) between 1996 and 2000. The research site was the Güvenç Basin located near Yenimahalle-Ankara with a drainage area of about 16.125 km⊃2. The aim of the study was to investigate the rainfall-runoff relationship for the Güvenç Basin using the stable isotope method in the separation of hydrographs. Recorded total discharge hydrographs are separated into their components using isotopes (oxygen-18, deuterium) contents. Among these samples, unit hydrographs from 2 single-peaked storm hydrographs were derived using both isotope and graphical (Barnes semi-log) methods and the derived unit hydrographs' peaks were compared. It was found that the contribution of subsurface flow originating from various sublayers of the basin is important in hydrograph separation when using the isotope method of approach. [ABSTRACT FROM AUTHOR]

Contributions to statistical theory and general methodology published in Biometrika, 1901–2000, are telegraphically reviewed. [ABSTRACT FROM PUBLISHER]

The spline smoothing approach to nonparametric regression is extended to cover the estimation of curves that branch at certain specified points in time. This extension is motivated and illustrated by data from an experiment on sunflowers. Apart from providing insight into this particular data-analytic problem, the work described demonstrates the power of the roughness penalty approach in coping with curve estimation of a nonstandard kind. Particularly in the context of certain experiments in horticulture and arboriculture, the experimental material may be treated identically to the control up to a certain known time part of the way through the experiment. To display and investigate the effect of treatments applied during growth it is of interest to estimate a branching curve. In the simplest case we want to study two growth curves that are common up to a certain known time and then diverge (or branch) after the application of a treatment to part of the experimental material. The spline-smoothing approach to nonparametric regression as discussed, for example, by Silverman (1985) can be extended to deal with branching curves by defining a roughness penalty that measures the local variation in all branches of the curve system. The usual residual sum of squares is penalized by the addition of a multiple of this roughness penalty, and the resulting penalized sum of squares can be minimized. The solution branching curve is made up of a number of cubic spline branches that fit together according to rules that are derived in the present article and that allow the curve system to be found by solving a set of sparse linear equations. A nonparametric approach to this curve estimation problem is virtually essential, because it is hard to contemplate extensions of the usual parametric growth curve models that allow for branching curves in any way that is not rather artificial.... [ABSTRACT FROM AUTHOR]

This paper studies the problem of tangible assets acquisition within the company by proposing a new hybrid model that uses linear programming and fuzzy numbers. Regarding linear programming, two methods were implemented in the model, namely: the graphical method and the primal simplex algorithm. This hybrid model is proposed for solving investment decision problems, based on decision variables, objective function coefficients, and a matrix of constraints, all of them presented in the form of triangular fuzzy numbers. Solving the primal simplex algorithm using fuzzy numbers and coefficients, allowed the results of the linear programming problem to also be in the form of fuzzy variables. The fuzzy variables compared to the crisp variables allow the determination of optimal intervals for which the objective function has values depending on the fuzzy variables. The major advantage of this model is that the results are presented as value ranges that intervene in the decision-making process. Thus, the company's decision makers can select any of the result values as they satisfy two basic requirements namely: minimizing/maximizing the objective function and satisfying the basic requirements regarding the constraints resulting from the company's activity. The paper is accompanied by a practical example. [ABSTRACT FROM AUTHOR]

In order to minimize the quantity of superconducting wire used in superconducting High Gradient Magnetic Separation (HGMS) systems, we developed two computational techniques to simulate the magnetic field created by superconducting solenoids: a detailed numerical model and a simplified graphical method. The numerical model is used as a standard of comparison to evaluate the accuracy of the graphical method. The evaluated error in the graphical determination of superconducting wire volume was less than 4.6% in hypothetical HGMS systems for purifying dissolved fission products in nuclear reprocessing. Compared with the case where an HGMS filter and a superconducting solenoid have the same length, our optimization technique shows that a large amount of wire reduction is possible. [ABSTRACT FROM PUBLISHER]