Minimum Area Method Research Articles

Minimum zone fitting and error evaluation for arc correction type convex contour of bearing roller

The minimum zone fitting and error evaluation for the arc-modified convex contour of a bearing roller have important applications for consistency detection and quantificational research of the elastohydrodynamic lubrication of a bearing roller. Based on the definition of the shape error and the geometric characteristics of the arc corrected roller convexity line of the bearing, a new fitting and error evaluation method for the total convexity contour of a bearing roller is presented. First, the reference cutoff points of the arc segment and straight line are determined based on the curvature difference of each measurement point. Then, the measuring points on both sides of the two reference cutoff points are selected as auxiliary cutoff points for arc fitting. The fitting error is obtained based on the minimum area method. Finally, a series of tangent equations are obtained based on the tangent principle between a line and two arcs, and the straightness error is determined by calculating the distances between the measuring points and the tangents. The example results show that an arc-modified convex contour can be fitted, and its global error can be evaluated effectively and precisely using the presented method. This study also provides a new idea for the minimum zone fitting of multi-segment curves along a plane.

Comprehensive Evaluation of NIMBY Phenomenon with Fuzzy Analytic Hierarchy Process and Radar Chart

The risk level of the NIMBY (Not In My Back Yard) phenomenon is crucial for the safety and economy of transmission and transformation projects which is rarely studied, especially for site selection and the construction of transmission lines and substations. In order to effectively evaluate the risk level to solve the dilemma caused by the NIMBY phenomenon, an evaluation method for quantifying the level of the NIMBY phenomenon is proposed. In this paper, thirty-one evaluation criteria and a risk model are put forward according to relevant laws and regulations that should be followed in the transmission and transformation project in China, then the scores corresponding to these criteria are obtained by a questionnaire survey. The radar chart method and minimum area method are applied to determine the weights of the element and unit layers. Furthermore, the overall risk level is evaluated by the fuzzy comprehensive evaluation method. In addition, a transmission and transformation project in Xi’an City, China, is used as an example to verify the correction of the risk model and its evaluation method. The results show that the weaknesses in the transmission and transformation project are analyzed, and suggestions for decreasing the risk level are put forward to minimize losses due to the NIMBY phenomenon.

Numerical Simulation and Experiment of Stress Relief and Processing Deformation of 2219 Aluminum Alloy Ring

Large aluminum alloy ring forgings are the core components of heavy-duty rocket fuel storage tanks, and the large residual stress inside the rings leads to poor shape accuracy of large thin-walled parts. The initial stress of the 2219 aluminum alloy ring blank was tested using the drilling method, and the creep constitutive coefficient of the 2219 aluminum alloy was determined through stress relaxation tests. The numerical simulation processes of thermal stress relief (TSR), vibration stress relief (VSR), and thermal–vibration stress relief (TVSR) were compared and established. Through the correlation analysis between the actual measurement results of residual stress and the simulation results, it can be seen that the strong correlation in three directions at each measurement point accounts for over 37.5%, and the moderate correlation accounts for over 62.5%. This indicates that the numerical simulation model of 2219 aluminum alloy ring containing initial residual stress can accurately reflect the size and distribution of residual stress inside the actual ring. The simulation results show that the derived constitutive model can describe the stress relaxation process of TVSR by combining a single thermal time effect stress relaxation constitutive theory with a VSR plastic deformation material model. The simulation models established above were used to calculate the residual stress homogenization ability of three types of aging. The results showed that VSR, TSR, and TVSR can homogenize and reduce the residual stress field inside the ring, improve the distribution of residual stress inside the ring, and have a better overall homogenization ability of TVSR. The VSR control has a certain effect on reducing and homogenizing residual stress, but compared with TSR and TVSR, the reduction and homogenization ability of residual stress control is limited. The homogenization control effect TVSR > TSR > VSR, and the maximum equivalent stress homogenization rates of VSR, TSR, and TVSR are 52.8%, 80.6%, and 82.2%, respectively. Then, numerical simulation technology was used to study how the initial residual stress in the blank causes the deformation of the ring during the thin-walled machining process. The roundness error theory of the minimum containment area method was applied to evaluate the deformation degree during the thin-walled numerical machining process, and the TVSR method was used for stress regulation. The deformation law of the thin-walled machining of the ring under different aging parameters was studied.

Diversity, Ecology and Therapeutic Properties of the Medicinal Plants in Ziban Region (Algeria)

With the aim to assess the floristic population diversity, distribution and therapeutic properties in the Ziban region (Algeria), a survey was conducted along two successive study years in the main area. The objective of this study was to contribute to the knowledge and description of this plant groups with exhaustive inventory spontaneous vegetation. In order to study the dynamics of medicinal plants, we used a quantitative method based essentially on the classic technique of linear surveys and floristic inventory using the minimum area method. The results showed that the floristic procession of medicinal plants is represented by 21 species belonging to the 13 families, with a total of 31 species for the 08 study stations, which represents 68% of the total procession. The results obtained showed that the overall recovery is higher at the Ain Ben Noui station with 69%, even if the clumps of Aristida pungens, Atractylis serratuloides and Atriplexhalimus are isolated and scattered. The lowest overall coverage at the Oumache station is less than 21%, as it is an area with sandy soils. The species that contribute most to the recovery of mobile sand accumulations is Astragalus armatus with a rate of 76.19% at the Ain Ben Noui station. Frequency results allowed us to say that Atriplex halimus and Zizyphus lotus are the ubiquitous species (100% of the surveys). On the other hand, Nitraria retusa, Teucrium polium, Shismus barbatus, Sueda mollis and Halocnemum strobilaceum are the species present in only one survey.

A Method for Identification of Anomalous Geological Zones

In the paper, a new approach to identifying zones with rare anomalous manifestations of geological processes is proposed. The approach is based on two one-class classification methods of machine learning: the method of minimum area of alarm and the method of preference. The algorithm of minimum area of alarm is nonparametric. It is trained on a sample of anomalous events and computes the field of anomalous zones. The knowledge obtained by this method is non-verbalized. The method of preference allows approximating the obtained solution by a rather simple logical rule that defines the anomalous region in terms of analyzed properties of the geological environment. Examples of this approach to finding areas of possible foci of strong earthquakes and to make a regional forecast of deposits are considered.

Analysis, Design, and Experimental Research of a Novel Wheelchair-Stretcher Assistive Robot

Life care for disabled or semi-disabled elderly has become an increasingly common problem in society. In this paper, a novel wheelchair-stretcher assistive robot, which can meet the physiological needs of patients, is investigated and designed. The following tasks are conducted: (1) the mecanum wheel is adopted as the executive device of the walking mechanism, and its kinematics is analyzed in detail. (2) A five-link mechanism with single degree of freedom is proposed to realize the folding motion of the robot. Through the minimum conclusive area method, the optimal sizes of the armrests link and the side link are 507.9, and 332.5 mm, respectively. Based on the force analysis of the linkage mechanism, six torsion springs and RV (rotate vector) reduction motor are used as the driving device, which reduces the driving torque of the motor. (3) Based on the STM32 (STMicroelectronics 32-bits Microcontroller) chip, and combined with the theoretical analysis, the mechanical structure and the control system of the whole prototype are designed, and the feasibility of each module is verified by experimental research. The results confirm that the proposed robot has good performance, and that the control algorithm for the walking mechanism and the lifting mechanism are suitable.

Machine Learning Methods for Seismic Hazards Forecast

In this paper, we suggest two machine learning methods for seismic hazard forecast. The first method is used for spatial forecasting of maximum possible earthquake magnitudes ( M m a x ), whereas the second is used for spatio-temporal forecasting of strong earthquakes. The first method, the method of approximation of interval expert estimates, is based on a regression approach in which values of M m a x at the points of the training sample are estimated by experts. The method allows one to formalize the knowledge of experts, to find the dependence of M m a x on the properties of the geological environment, and to construct a map of the spatial forecast. The second method, the method of minimum area of alarm, uses retrospective data to identify the alarm area in which the epicenters of strong (target) earthquakes are expected at a certain time interval. This method is the basis of an automatic web-based platform that systematically forecasts target earthquakes. The results of testing the approach to earthquake prediction in the Mediterranean and Californian regions are presented. For the tests, well known parameters of earthquake catalogs were used. The method showed a satisfactory forecast quality.

Outlanders in an unusual habitat : Holothuria mammata (Grube, 1840) behaviour on seagrass meadows from Ria Formosa (S Portugal)

Holothuria mammata is one of the new target species from the Mediterranean and Atlantic. Usually, it inhabits rocky bottoms, staying in crevices and holes during the day and leaving them in the night for feeding on sandy bottoms. However, it can be found in unusual habitats such as seagrass with diurnal and nocturnal feeding. This study provides information for the first time on the behaviour, density and small scale distribution of H. mammata in a seagrass habitat from Ria Formosa (S Portugal). To reach these aims, a mark/recapture methodology was used. Abundance was estimated through R statistical software v.2.15.3 (package “Rcapture”). The minimum area method was applied in GRASS GIS v.6.4.2 for home range. Size distribution was estimated applying a ShapiroWilk test. Rayleigh test for randomness was applied to study the directionality of movements. A circular one-way ANOVA was used to test for differences in movement direction. Capture probability was higher on seagrass than sand and the total length of the individuals ranged from 13 to 25cm. Movement speed was between 4.7 and 14.7 m day-1. Movements were not directional. H. mammata differs in its behaviour from the related Holothuria arguinensis occurring in the same habitat.

On the design of power- and area-efficient Dickson charge pump circuits

This paper aims at investigating some methods for designing an area- and power-efficient Dickson charge pump circuit for on-chip high-voltage source generation. A comprehensive study on two conventional methods, with one of them based on optimizing the number of stage for minimum silicon area (minimum area method) and the other for maximum power efficiency (optimal power method), will be presented by considering both top- and bottom-plate parasitic capacitances. It was found that when the parasitic factors are as large as 0.1, the area and power efficiencies of the charge pumps designed with either the optimal power or minimum area method do not have much degradation. However, when the parasitic factors are small, charge pumps designed with the optimal power and minimum area methods can, respectively, result in a large area and poor power efficiency. The power efficiency of the charge pump designed with the minimum area method may be reduced by 50 %, while the area of the charge pump designed with the optimal power method can be 1---2 times larger, when the parasitic factors are 0.01. Hence, neither the optimal power nor minimum area methods should be used when the parasitic factors are small, unless the power or area is the only concern in the design. With this connection, the number of stage which leads to an area and power-efficient charge pump is suggested. Validity was proved by the good agreement between the simulated and the expected results for some designed charge pump circuits of the proposed design strategy.

Research and application of surface feature analysis for scatter data points

A new effective algorithm of surface feature analysis based on scattered data points is proposed, which includes three steps:First, the local surface reference data parameterized using method of minimum area for enclosure rectangle is obtained based on R*-tree dynamic spatial access model; Second, the surface curvature is computed on the basis of the polynomial surface fitted by the parameterized data in the first step; Third, the distribution of surface feature is reflected through color plot mapped by surface curvature. Experimental examples show that this algorithm can be used by various data, high operating efficiency and accuracy of surface feature analysis.

Performance Evaluation of Superheated Steam Temperature Control System based on Tuning Methods of Analog Controllers

This paper explains the method of obtaining the best analog controller for a superheated temperature control system based on the least value of integral time weighted absolute error. The superheated steam temperature system is of fifth order model. This higher order model is converted into delay plus first order model by minimum area method. Analog controllers (P, PI, PID) are designed for Superheated steam temperature system by applying different turning methods. Simulations are performed by using the fifth order mathematical model of the system. The least value of integral time weighted absolute error decides the best analog controller.

Machine vision based inspection of oil seals

Abstract In this research, the dimensions (inner and outer diameters) and surface defects of oil seals are measured or inspected by a machine vision system. There are four steps of the measurement: (1) obtain the threshold value of an image, (2) use that value and a boundary-tracking method to ascertain the positions of boundary points, (3) use the Gaussian technique to smooth the boundary points, and (4) use the minimum errors area method to calculate inner and outer diameters. Before inspecting for surface defects, the center position must be calculated. With that position determined, the gray levels of the circumferential pixels in the inspected regions can be obtained. To check the gray levels, an improved moving-range chart and an individual observation control chart are employed, thus completing the inspection.

Analysis of a membrane/distillation column hydrid process

Distillation of low relative volatility mixtures is highly energy intensive and can require tray numbers greater than 150. Two design methods for a hybrid process are given to minimize the tray number in a distillation column that contains a membrane unit: the minimum area method and the Smoker's equation method. The Smoker's equation method is used to study the effect of different membrane variables on the tray number. The optimal position of the membrane unit on the distillation column is close to the feed to the distillation column. The number of trays in the distillation column does not decrease indefinitely with an increase in the membrane surface area due to the decreased selectivity. Maximum reduction in tray number of the distillation column occurs when the ration of the membrane feed rate to the membrane area is close to 0.1 mol/m 2 s. An analytical expression for optimal placement of a membrane unit on a distillation column is given for a special case using the minimum area method. Finally, simulations were performed to prove that both methods are equally valid.

Estimating the home ranges of sugar gliders (Petaurus breviceps) (Marsupialia: Petauridae), from grid-trapping and radiotelemetry

In this study, we examined the number of captures and radio-locations of sugar gliders (Petaurus breviceps) necessary to give reasonable estimates of home ranges. Using home ranges determined by radiotelemetry (RTHR) as a standard, we compared nine methods of estimating trap home range (THR) from grid-based mark-recapture data. Correlation analysis was employed to determine which method of estimating THR most closely correlated with RTHRs. A minimum of 12 captures appears to be adequate for reasonable long-term THR estimates derived from the harmonic mean measure (HMM, 50% isopleth). When RTHRs were estimated by either the minimum convex polygon method (MCP) or the HMM (95% isopleth) from loci collected every 30min, a minimum of 36 radio-locations was adequate. Mean RTHR estimates for identical data sets were 53 775m*2 and 35 333m*2 calculated from the MCP and the HMM (95% isopleth) respectively. A number of methods for analysing grid-trapping data produced THR estimates that were significantly correlated with RTHR estimates. Correlations were highest when RTHRs were estimated with the HMM as opposed to the MCP. RTHR estimates derived from the MCP were most strongly correlated with THR estimates derived by the minimum area method, HMM (50% isopleth) and observed range circle (r*2>0.48). When RTHR estimates were derived from the HMM (95% isopleth), the same correlations were higher (r*2>0.88) and THRs estimated by the boundary-strip methods and the adjusted range circle were also highly correlated (r*2>0.65). The significance of the correlations suggests that reasonable short-term THR estimates may be obtained from small capture samples by these above-mentioned methods of calculation. The HMM appeared to exhibit the greatest overall utility, with both radio-tracking and grid-trapping data. The success of the HMM in describing home range appears to be in its ability to depict centres of activity. The technique is most appropriate for animals such as sugar gliders which use concentrated but patchily distributed food resources, and consequently display uneven patterns of use of space.

A study of home range, movements and shelter use in adult and juvenile echidnas, Tachyglossus aculeatus (Monotremata: Tachyglossidae), in Western Australian wheatbelt reserves.

Ten adult and six juvenile Tachyglossus aculeatus were radio-tracked in two Western Australian wheatbelt reserves between January and November 1988. Mean body weights were 4.5 ± 0.2 kg (SE) (adults) and 2.5 ± 0.1 kg (juveniles). A maximum adult weight of 5.9 kg was recorded. Home-range determinations were based on 1848 observations (range 31 to 261 per echidna), using a modified minimum area method. Home-range sizes were 65 ± 17 ha (SE) (adults) and 23 ± 6 ha (juveniles), and these overlapped substantially. Home-range sizes and body weights were not correlated. Adults preferred low density burrows in heath at all times of year, especially in winter months. Juveniles showed no clear shelter preferences. Some shelters were used repeatedly, often with conspecifics. Shelter reuse was inversely correlated with home range size. Periodically, some T. aculeatus left reserves for different periods, using road verges and crossing long distances of farm land. These movements could not be explained by reference to mate search because they involved adults and juveniles, and occurred at varying times, sometimes well outside their known breeding period. All juveniles dispersed between August and October, at an estimated 12 months of age.

Time Intervals for Estimating Pronghorn and Coyote Home Ranges and Daily Movements

The authors compared estimates of home range and daily movement for radio-tagged pronghorns (Antilocapra americana) and coyotes (Canis latrans) based on subsamples of data collected at short time intervals during nonconsecutive 24-hour sampling sessions. Home-range size, calculated by either the minimum area method or the linked-cell grid method, and daily distance traveled were underestimated when sampling intervals were based on statistically independent data. Autocorrelated data provided a better estimate of true home-range sizes than independent data for all sampling intervals. Estimates of daily movement based on sampling intervals > 4 hours for pronghorns and >3 hours for coyotes were not correlated with the actual distance traveled. These relationships suggest that restricting sampling effort to statistically independent time intervals sacrifices biologically significant information.

Maximization of entropy and minimization of area as criteria for NMR signal processing

The process of maximizing the entropy of an NMR spectrum can be approximated by minimizing the total area enclosed between the spectrum and the baseline. The two criteria become mathematically equivalent in the limit of a high signal-to-noise ratio. When noise is present the maximum-entropy and minimum-area reconstructed spectra show similar discrimination against out-of-phase signals, sinc ripples, and electronic noise; but algorithms based on the minimum-area method require shorter computer processing times.

Comparison of trap- and radio-revealed home ranges of the brush-tailed possum (Trichosurus vulpeculaKerr) in New Zealand lowland forest

Abstract Four brush-tailed possums were fitted with radio transmitters and located hourly on 3 nights each month for 2 years. The home ranges found by this technique are compared with those revealed by live-trapping on a 30 × 30 m interval grid in lowland indigenous forest during the same 2-year period. The minimum-area method, a modified minimum-area method, range lengths, 3 boundary-strip methods, and Koeppl's elliptical method are compared. Estimates of home range based on trap-revealed and radio-revealed data differed greatly; the areas of home ranges found by the use of radios were mostly considerably larger than those revealed by live-traps. The activity centres of the home ranges found by trapping corresponded well with those found by radio-tracking.

Coyote Movements, Habitat Use, and Food Habits in Southwestern Oklahoma

Coyote Movements, Habitat Use, and Food Habits in Southwestern Oklahoma

A Radiotracking Study of Home Range and Activity of the Brown Lemming (Lemmus trimucronatus)

Home range was determined for brown lemmings by a radiotracking procedure throughout June and July 1972–1973 with 1795 location fixes obtained for 12 adult males, 10 adult females, and three juveniles (<20 grams) in 1972 and 3000 fixes recorded from 13 males and 12 females in 1973. Home range was calculated by the minimum area method. For 1972 animals mean male home range measured 1.33 ha (hectare) (S.D. .986, range .183 to 2.85 ha); mean female home range was .681 ha (S.D. .901, range .143 to 1.454 ha). For 1973 animals, mean male home range was .876 ha, (S.D. 1.0, range .0004 to 2.80 ha); mean female home range was .413 ha, (S.D. 1.03, range .015 to 1.68 ha). Males tended to have larger home ranges than females; 1972 home ranges tended to be larger than those of 1973 but these differences were not statistically significant. An indirect measure of activity termed change in location was defined as a difference of 2° or more in successive fixes. An analysis of this measure indicated males were significantly more active than females during both years, and 1972 animals were significantly more active than those studied in 1973. Activity was also measured directly by a telemetering system. For a sample of three males and three females, it was determined that males were active (for example, moving, feeding, and grooming) 75 percent of the time during a 24-hour period; females were active 67 percent of the time. Males spent about 69 percent of a 24-hour period outside of burrows, females 55 percent.