Fold Lines Research Articles

A quadratic weighted centroid algorithm for tunnel personnel positioning

To improve the accuracy and generalization of tunnel personnel positioning systems, this article proposes a quadratic weighted centroid algorithm. By adopting a Gaussian filter model to improve the range accuracy of the received signal strength indicator algorithm and combining the centroid algorithm and weighting factor with a trilateration positioning model, a quadratic weighted centroid algorithm is proposed to improve the positioning accuracy of unknown positioning nodes. The key ideas behind the quadratic weighted centroid algorithm include an optimization of the received signal strength indicator range value scheme, a centroid algorithm based on trilateral measurement positioning, and a weighting factor to improve the positioning accuracy of the trilateral centroid positioning algorithm. Compared with the centroid algorithm, the Min-Max multilateration algorithm, and the weighted centroid based on distance algorithm, the simulation results showed that (1) the positioning performance of the quadratic weighted centroid algorithm was superior to the other three algorithms; (2) when the reference nodes were symmetrically arranged, the positioning accuracy was higher than a fold line layout; and (3) when the lateral reference node spacing was extended from 20 to 30 m, the average positioning error met positioning accuracy requirements, which could reduce overall system costs.

Numerical Simulation of the Effect of Small-Particle Size Droplet Removal in a Ship Desulfurization Tower Demister

The demisting efficiency of three structure demister and the influence of hook plate on the efficiency of demister were analyzed using fluent software. For a droplet with a particle size of 20μm, when α= 90°, L=20mm, and the inlet speed v=5m/s, the demisting efficiency of the wave plate demister has reached 96.67%. After installing the hook plate, the efficiency of the wave plate demister was significantly increased, the efficiency of the streamline plate demister was more than doubled, and The efficiency increase of the fold line plate demister was small. Finally, the comprehensive analysis showed that the wave plate demister had the highest efficiency and increasing the hook plate could increase the demisting efficiency but at the same time increased the pressure drop.

Dynamic modeling for foldable origami space membrane structure with contact-impact during deployment

The dynamic modeling for the foldable origami space membrane structure considering contact-impact during the deployment is studied in this paper. The membrane is discretized using the triangular elements of the Absolute Nodal Coordinate Formulation (ANCF), and the stress–strain relationship of the membrane is determined based on the Stiffness Reduction Model (SRM). A mixed method is proposed for the frictionless contact problem by combining the membrane surface-to-surface (STS) contact elements with the membrane node-to-surface (NTS) contact elements to improve precision. Compared with the traditional STS contact elements, the mixed method can effectively avoid mutual penetration of the element boundaries, especially for the foldable origami membrane structures undergoing overall motions. The penalty method is adopted to enforce the nonpenetration condition. Moreover, special constraints are built for the fold lines, and then the dynamic equations of the membrane multibody system considering the damping effect are formulated. The dynamic deployment procedure of a leaf-in origami membrane structure with contact-impact is performed employing this present mixed method. The results demonstrate the effectiveness and superiority of the presented mixed method in the solution of the complicated contact problem, and the influence of the contact-impact on the dynamic performance is analyzed.

Nonlinear rotational stiffness and clash prevention in perforated steel fold lines

Characterisation of the rotational stiffness of fold lines is necessary to analyse the compliant behaviour of origami-inspired structures, however limited data exists for fold lines manufactured from high-strength materials such as steel. This paper establishes a reliable characterisation of perforated steel fold lines, with three improvements to existing knowledge of their mechanics. First, a manufacture and testing method was developed for consistent measurement of fold line moment responses, over a large rotation range from an unfolded 0° up to 140°. Second, testing data showed inconsistencies with the bilinear analytical model commonly used to describe nonlinear fold line responses, so an enhanced nonlinear model was adapted and shown to give an improved fit over the initial elastic-plastic transition stage. A thick panel clash behaviour was also identified as causing a complex stiffening behaviour at large rotation angles; an ‘over-kerf’ manufacturing strategy was developed to eliminate this clash behaviour, allowing the enhanced model to give a good description of fold rotational stiffness over the complete tested range of rotation. Third, a parametric experimental study obtained fold line responses over a range of steel thicknesses and fold line parameters. This was used to give additional insight in the relative efficacy of bilinear and enhanced models and the interaction between clash behaviour, sheet thickness, and manufacture kerf.

Using Models to Build Fraction Understanding

We share the impact different models have on students' fraction thinking. We have come to understand, through several teaching experiments, how fraction circles, paper folding and number lines support students' learning about key fraction ideas including the role of the unit, partitioning, and fraction order.

Inline corrugated board creasing

Corrugated board sheets that are used in corrugated boxes have to be cut and creased before being folded and glued in the shape of the final box. Cutting and creasing are done by rolling a sheet of corrugated between rollers, carrying ribs that either cut or crease the corrugated. This technology is applied for decades and performs very well. However the rollers have to be prepared in advance and one pair of rollers is required for each type and each dimension of a box.In case boxes have to be produced on demand, each and every box might have a specific size. Cutting and creasing between rollers is not possible and an alternative method is required. A corrugated board is put on an air permeable carpet. Underneath the carpet vacuum is created to prevent the board from moving. It is then cut using a sliding or a rolling knife. Creasing is done by a small wheel that is rolled over the cardboard along the folding lines, called top side creasing.Numerous types of corrugated board exist in terms of flute sizes and paper types. Creasing can be done parallel to the flutes or under an angle. There is a lack of knowledge regarding the optimal shape of the creasing wheel used for top side creasing. This paper presents experimental research aiming at the optimal shape of a multi-purpose creasing wheel.

Mate Analysis of Comprehensive Treatmentstrategy for Advanced Rectal Cancer

AIM: Objective to evaluate the clinical value of therapeutic lateral lymph node dissection in advanced rectal cancer after neoadjuvant radio-chemotherapy in patients with peritoneal retroperitoneum under MR suggesting perivascular iliac lymph node enlargement (lymph node diameter > 8mm). Methods: Because of this study is a retrospective study, the propensity to evaluate matching group is adopted to one group to Fujian Medical University Union Hospital, Fujian province hospital from January 2009 to June 2014 treated 103 cases of rectum MR images after neoadjuvant chemoradiation weeks iliac blood vessels have the progress of the lymph node enlargement period under peritoneal fold return rectal cancer line TME + therapeutic cases of lateral lymph node cleaning; In the group 2, 192 cases with the same tumor site, stage, type, gender and age as group 1 or similar were matched for the same period by propensity assessment, while the group 2 received TME only. The incidence of pelvic autonomic nerve injury after surgery, the 3-year local recurrence rate of pelvic cavity, and the 5-year tumor-free survival rate were compared between the two groups, so as to explore the clinical value of therapeutic periiliac dissection for advanced rectal cancer under peritoneal reflux. Results: The local recurrence rate of pelvic cavity in group 1 and group 2 was 2.91% (3/103) and 9.90% (19/192), respectively, 3 years after operation (P<0.05). Postoperative dysuria in group 1 and group 2 was 14.56% (15/103) and 5.21% (10/192), respectively, with significant difference (P<0.05). Postoperative sexual dysfunction in group 1 and group 2 was 12.50% (7/56) and 2.15% (2/93), respectively, with significant difference (P<0.05). The 5-year survival rates of group 1 and group 2 were 54.37% (56/103) and 51.56% (99/192), respectively, with no significant difference (P›0.05). The liver metastasis rates of group 1 and group 2 were 26.21% (27/103) and 29.17% (56/192), respectively. Lung metastasis rates in group 1 and group 2 were 19.41% (20/103) and 19.27% (37/192), respectively. Conclusion: After neoadjuvant chemoradiotherapy for advanced rectal cancer, selective lymphatic dissection along the iliac vessels guided by rectal magnetic resonance can reduce the local pelvic recurrence of patients for 3 years, but increase the probability of pelvic autonomic nerve injury, and periiliac lymph node dissection will not increase the 5-year survival rate of patients.

Prevention of hyper- and hypotrophic scars through surgical incisions in the direction of the “main folding lines” of the skin

Prevention of hyper- and hypotrophic scars through surgical incisions in the direction of the “main folding lines” of the skin

Rational Parametric Equation of a Circle From a Paper Fold

SummaryPlace a square sheet of paper with side length 1 into the first quadrant of a coordinate system in such a way that the lower-left corner coincides with the origin. Look at the set of points that are obtained by folding the lower-right corner of the sheet along a line passing through the origin. The points obtained in this fashion will lie on the unit circle whose center is the origin. By making use of two similar triangles, the illustration gives rise to a rational parametrization of the unit circle. The parameter t is the distance from the lower-right corner of the sheet to the point of intersection of the fold line with the right edge of the paper.

The least symmetric crystallographic derivative of the developable double corrugation surface: Computational design using underlying conic and cubic curves

Flat-foldable origami tessellations are a rich source of inspiration in the design of transformable structures and mechanical metamaterials. Among all such tessellations, the developable double corrugation (DDC) surface, popularly known as the Miura-ori, is perhaps the most ubiquitous origami pattern in science, engineering, and architectural design. Origami artists, designers, and researchers in various fields of science and engineering have proposed a range of symmetric variations for this pattern. While designing many such derivatives is straightforward, some of them present considerable geometric or crystallographic challenges. In general, the problem of finding flat-foldable derivatives for a given origami tessellation is more challenging for less symmetric descendants. This paper studies the existence and design of the least symmetric derivative of the Miura fold pattern with minimal unit cell enlargement in the longitudinal direction. The course of this study raises a fundamental problem in the flat-foldability of quadrilateral-shaped flat sheets on fold lines through their vertices. An analytical solution to this general problem is presented along with solutions for the special cases of convex quadrilaterals.

Virtual unfolding of folded papyri

Abstract The historical importance of ancient manuscripts is unique since they provide information about the heritage of ancient cultures. Often texts are hidden in rolled or folded documents. Due to recent improvements in sensitivity and resolution, spectacular disclosures of rolled hidden texts were possible by X-ray tomography. However, revealing text on folded manuscripts is even more challenging. Manual unfolding is often too risky in view of the fragile condition of fragments, as it can lead to the total loss of the document. X-ray tomography allows for virtual unfolding and enables non-destructive access to hidden texts. We have recently demonstrated the procedure and tested unfolding algorithms on a mockup sample. Here, we present results on unfolding ancient papyrus packages from the papyrus collection of the Musee du Louvre, among them objects folded along approximately orthogonal folding lines. In one of the packages, the first identification of a word was achieved, the Coptic word for “Lord”.

Activity law and hydraulics mechanism of landslides with different sliding surface and permeability in the Three Gorges Reservoir Area, China

The Three Gorges Hydropower Station is the largest hydropower station worldwide and the largest project ever built in China. There are about 2619 ancient landslides affected by reservoir level fluctuation in the Three Gorges Reservoir (TGR) area. More than 670 landslides have been reactivated and eight landslides have failed since the impoundment of the reservoir in June 2003, which seriously threatens people's safety and property. In this study, taking a large number of re-active and failed landslides as statistical samples, the activity and displacements of the reservoir landslide with special regard to different sliding surface and permeability are analyzed and discussed. It is noted that a significant correlation between the landslide movement and the reservoir filling process. The re-active landslides are mainly concentrated in the initial stage of water storage, and the frequency of activation as well as the degree of deformation decrease gradually after the third phase of water storage (175 m). Then the four dominant combinations of the inducing factors of re-active landslide are presented: (a) drawdown of water level, straight line sliding surface, 20–40% degree of immersion, and weak permeability; (b) drawdown of water level, arc sliding surface, 40–60% degree of immersion, and medium permeability; (c) raising of water level, fold line sliding surface, 20–40% degree of immersion, and good permeability; (d) raising of water level, chair shaped sliding surface, 0–20% degree of immersion, and good permeability. Furthermore, when the rate of the reservoir level fluctuation is greater than the permeability coefficient, the shape of sliding surface is from the straight line - the arc - the fold line - the chair shaped, and the hydraulics effect of reservoir water on landslide shifts from the seepage pressure effect to the buoyant effect. Meanwhile, the impact of the reservoir water filling on the landslide reactivation changes from favorable to worse, and the impact of the reservoir water drawdown on the landslide reactivation changes from worse to favorable.

Design of Negative Pressure Spiral Feeding Device for Tangential and Longitudinal Axial Intersection of Combine Harvester

A difficult problem occurred with straw clogging at the tangential and longitudinal axial intersection of rice combine harvesters, which seriously affected the efficiency and reliability of the threshing cylinder. The primary objective of this paper was to design a negative pressure spiral feeding device by CFD (computational fluid dynamics). The negative pressure spiral feeding combined structure of the tangential threshing cylinder and longitudinal axial threshing cylinder was established by Pro/E software. Then, the flow path model of the negative pressure spiral feeding device was analyzed by CFD. The airflow velocity distribution of the spiral feed head semicircular cross section and power consumption of the longitudinal axial spiral feeding head were used to verify the effectiveness and rationality of the negative pressure spiral feeding device. The results showed that the two-blade spiral structure and 30 mm pitch shroud structure were more suitable to ensure the smooth flow of straw at the tangential and longitudinal axial intersection. The resistance of the feeding head would cause the power consumption curve fluctuation. The power consumption curve of the improved shroud spiral feed structure was a stable regular fold line without upward trend. When the power consumption curve has an always upward trend, it means that congestion is about to happen. The characteristics of the power consumption curve indicated that the shroud negative pressure spiral feed device designed in this paper was reasonable and effective.

A Fault Diagnosis Algorithm for Microgrid Three-Phase Inverter Based on Trend Relationship of Adjacent Fold Lines

Fault diagnosis of a microgrid inverter is susceptible to asymmetric interference such as overcurrent component and bias component. It may lead to uncertain fluctuation of diagnosis features, even false alarm and erroneous triggering of protection units. Therefore, for a microgrid inverter, a robust fault diagnosis algorithm is necessary to cope with such asymmetric interference. Motivated by this observation, first, a new fault feature extraction method is proposed in this paper by the trend relationship of adjacent fold lines for data curve. It can be used to extract the fault feature and it is not affected by asymmetric interference. Second, a trend encoding method is proposed to encode the trend feature of a fold line, which is well visualized, easily identified, stored, and calculated. Third, two main indexes are calculated by the encoded features to represent the degree of abnormal and location information. Fourth, the diagnosis results are realized through the logical relation operations. Compared with the existing fault diagnosis algorithms, multiswitches fault can be accurately diagnosed in the case of asymmetric interference. Finally, the detailed experiment results and comparisons are shown to validate the proposed algorithm.

Effects of orbital septum fat redistribution on multiple malformation of upper eyelid after blepharoplasty

Objective The multiple malformation of upper eyelid, including the excessive width of fold line, sunken and/or multiple folded upper eyelid are the common complications after blepharoplasty. The aim of this study was to investigate the clinical effect of orbital septum fat redistribution on correcting these deformities. Methods From September 2015 to September 2017, 38 patients with multiple malformations of upper eyelid were treated. The incision of upper eyelid and the excessive skin was designed and resected. After completely relieving the scar adhesion zones, we set the lateral orbital septum fat free and transposed it to the inner side of orbital septum or superior border of tarsus with suturing fixation. Then we routinely completed the double eyelid operation. Results Thirty-eight patients with multiple malformations of upper eyelid were treated successfully. The patients were followed up for 6 months to one year, and the results were totally satisfactory. The operation was not performed again. Conclusions The orbital septum fat redistribution can successfully correct the multiple malformation of upper eyelid. It should become a regular procedure in blepharoplasty. Key words: Double eyelid reconstruction; Sunken upper eyelid; Excessive width of fold line; Multiple folded upper eyelids; Orbital septal fat replacement

Minimal Scar Formation After Orthopaedic Skin Incisions Along Main Folding Lines.

Patients, particularly those who are young, often develop noticeable orthopaedic scars. In order to achieve minimal scarring, surgeons should attempt to place incisions in skinfolds or skin creases. Optimal incision lines can be determined from the direction of stretch marks (striae distensae), which develop perpendicular to lines of tension or main folding lines. A composite diagram of photographs of 213 individuals with striae distensae was created and compared with 276 images of incisions and scars derived from the Internet. Classically described Langer cleavage lines often run counter to real tension lines and poorly predict the optimal direction for skin incisions. Whenever possible, main folding lines should be utilized as a guide in planning surgical incisions for young patients as well as for correction of problem scars.

Functional morphology and structural characteristics of the hind wings of the bamboo weevil Cyrtotrachelus buqueti (Coleoptera, Curculionidae)

ABSTRACTResearch data of the microstructure and surface morphology of insect wings have been used to help design micro air vehicles (MAV) and coating materials. The present study aimed to examine the microstructure and morphology of the hind wings of Cyrtotrachelus buqueti using inverted fluorescence microscopy (IFM), scanning electron microscopy (SEM), and a mechanical testing system. IFM was used to investigate the distribution of resilin in the hind wing, and SEM was performed to assess the functional characteristics and cross-sectional microstructure of the wings. Moreover, mechanical properties regarding the intersecting location of folding lines and the bending zone (BZ) were examined. Resilin, a rubber-like protein, was found in several mobile joints and in veins walls that are connected to the wing membranes. Taken together, structural data, unfolding motions, and results of tensile testing suggest two conclusions on resilin in the hind wing of C. buqueti: firstly, the resilin distribution is likely associated with specific folding mechanisms of the hind wings, and secondly, resilin occurs at positions where additional elasticity is needed, such as in the bending zone, in order to prevent structural damage during repeated folding and unfolding of the hind wings. The functional significance of resilin joints may shed light on the evolutionary relationship between morphological and structural hind wing properties.

Novel gusset plate design using high strength steel and heat treatment

Gusset plates for high seismic regions are designed to allow brace buckling while minimizing damage to the beam or column by having large rotational capacity. The conventional approach is to use linear fold lines to permit the rotation, which can result in overly large plates. A more compact design uses elliptical fold lines, but both designs can lead to damage to welds with surrounding components. In this paper, a new approach is proposed by defining a yield path through the use of a locally weakened zone created through heat treatment. In this method, inelastic deformation will be concentrated into the weakened zone. The objective of the research is to develop a connection in which the failure mechanism is tightly controlled, which will eliminate unexpected damage mechanisms and result in small gusset plate designs. A series of microhardness, tensile, and bend tests are performed on the heat treated steel samples to study the effect of heat treatment on their mechanical properties. A design methodology for the heat treated gusset plate is proposed, and finite element analysis is used to compare the behavior of the proposed gusset plates.

A meshless method for the nonlinear von K\xe1rm\xe1n plate with multiple folds of complex shape

We present a meshless discretisation method for the solution of the non-linear equations of the von Kármán plate containing folds. The plate has Mindlin–Reissner kinematics where the rotations are independent of the derivatives of the normal deflection, hence discretised with different shape functions. While in cracks displacements are discontinuous, in folds, rotations are discontinuous. To introduce a discontinuity in the rotations, we use an enriched weight function previously derived by the authors for cracks (Barbieri et al. in Int J Numer Methods Eng 90(2):177–195, 2012). With this approach, there is no need to introduce additional degrees of freedom for the folds, nor the mesh needs to follow the folding lines. Instead, the folds can be arbitrarily oriented and have endpoints either on the boundary or internal to the plate. Also, the geometry of the folds can be straight or have kinks. The results show that the method can reproduce the sharp edges of the folding lines, for various folding configurations and compare satisfactorily with analytical formulas for buckling or load-displacement curves from reference solutions.

Krakowskie pamiątki po Jędrzeju Śniadeckim

Jędrzej Śniadecki memorabilia from Kraków This article presents the results of a search for memorabilia related to Jędrzej Śniadecki (1768–1838), a prominent Polish chemist, doctor and columnist. He was born in Żnin in Greater Poland, educated in Kraków and his professional life was associated with Vilnius. This search for memorabilia related to Jędrzej Śniadecki (except for archival materials) was conducted in Vilnius and Kalczuny in Belarus, which has a school museum devoted to Jędrzej Śniadecki and other scholars. However, no personal belongings related to the scholar were found at these locations. At present, the only items known to have belonged to Jędrzej Śniadecki are included in the collection of the Jagiellonian University in Kraków. These items are: an 18th-century microscope, a line gauge dating to 1834 and a ceremonial spade which formed an element of the academic regalia worn by professors of the Imperial University of Vilnius. The article discusses the above mentioned items and their provenance. In 1964, the microscope was transferred to the Jagiellonian University Museum in Kraków from the Botany Unit of the Jagiellonian University by Professor Władysław Szafer (1886–1970) with the information that it had belonged to Jędrzej Śniadecki. It is a Cuff-type microscope made of wood, cardboard, bone and glass, manufactured in Nuremberg. The microscope attributed to Śniadecki bears the initials JFF. It is not a high quality product, but microscopes from Nuremberg gained popularity as toys rather than test instruments. The second item attributed to Jędrzej Śniadecki is a 24-inch folding line gauge which consists of two parts. It was bought in 1957 by the Jagiellonian University Museum from Professor Andrzej Ciechanowiecki, who had inherited it in 1945 from Maria Kazimierzowa Osiecimska-Czapska (née Śniadecka), a great-granddaughter of Jędrzej Śniadecki. In the family, this item was regarded as a memento of Jędrzej Śniadecki which came from Boltup. Another memento of the scholar is a ceremonial spade. Tradition has it that it belonged to Jędrzej Śniadecki and was an element of the ceremonial regalia worn by the professors of the Imperial University of Vilnius. In 1878, the spade was donated to the Archaeological Cabinet of the Jagiellonian University by Kazimierz Jan Wilczyński (1806–1885), a doctor, art collector, publisher and member of the Vilnius Temporary Archaeological Commission.