Linear Segments Research Articles

Typical motion-based modelling and tracking for vehicle targets in linear road segment

In this paper, a typical motion-based modelling and tracking issue is investigated for vehicle targets in linear road segment by a variable structure multiple model (VSMM) method. Vehicle target motions in a road with multiple lanes are described by typical lane keeping and lane changing manoeuvres. To describe trajectories of typical manoeuvres, an Ornstein–Uhlenbeck process and a sine half-cycle are used to model lane keeping and lane changing motions in lateral direction, respectively. Note that starting point and length of lane changing motion are unknown in target tracking. Time-varying model sets are designed based on the current motion model with different motion parameters. A VSMM tracking frame is constructed to obtain target state estimates with time-varying model set. The effectiveness of the proposed typical motion-based tracking scheme is displayed by simulation results on road vehicle tracking.

Smoothing interpolation of five-axis tool path with less feedrate fluctuation and higher computation efficiency

Five-axis machine tools are widely used in aerospace, die and mold industries. Most of the time, the tool path is described by connecting a series of short linear segments. The tangency discontinuity of the linear segments leads to the discontinuity of the kinematic profiles, hence generating discontinuous interpolation points, and resulting in fluctuation of machine motion, which reduces the machining efficiency and causes excessive tracking and contouring errors. This paper aims to generate smooth interpolation points at servo sample intervals with the proposed G2 continuous five-axis corner rounding algorithm suitable for reducing feedrate fluctuation along the smoothed toolpath and improving machining efficiency, and the modified jerk-limited feedrate planning algorithm suitable for eliminating feedrate fluctuation within the feedrate planning units and improving interpolation computation efficiency. In this paper, the five-axis linear segments are first smoothed by curvature-optimized cubic Bezier splines, which reduces the number of the feedrate planning units along the smoothed toolpath and improves machining efficiency. Then, the jerk-limited feedrate planning algorithm is modified to ensure that the time interval of each different scheduled feedrate phase is an integer multiple of the axis position control loop closure time (i.e. servo sample interval), which eliminates the feedrate fluctuation within each feedrate planning unit and reduces the interpolation computation load of position command in each interpolation period (i.e. servo sample interval). At last, the effectiveness of the proposed algorithm is demonstrated with simulations and experiments following a five-axis, curved tool path on a CNC (Computer Numerical Control) machine tool.

Centaurea ozrenii (Asteraceae) ‒ a new local endemic and extremely rare species from Mt. Ozren near Sjenica in Serbia

A new species of Centaurea sect. Acrocentron (Asteraceae) was found on the Ozren mountain in southwestern Serbia near Sjenica and named as Centaurea ozrenii. It inhabits xerophilous and steppe-like habitats, on ultramafic geological substrate. Morphologically, it is close to C. calocephala, C. chrysolepis, C. orientalis, C. murbeckii, C. kotschyana and the recently described C. zlatiborensis. The most distinctive morphological features of the new species are undivided to simply pinnatisect (non lyrate) subglabrous leaves, with linear segments, upper leaves with an aristate apex and cream coloured to pale yellow florets of which the outer are much longer than the inner ones. The phyllaries are intermediate in relation to C. calocephala and C. kotschyana. The chromosome number of the new species is 2n = 22. Thorough field investigations confirmed the presence of C. ozrenii only at this localized site on Mt. Ozren with a population of 13 clusters of individuals with 23-52 flowering stems in an area of about 50 m2. Applying the IUCN Red List categories and criteria to the available data categorised C. ozrenii as a Critically Endangered (CR) species.

Preparation and performance testing of novel bendable optically transparent fluorinated hyperbranched linear long chain segment poly(amide-imide) films

A series of fluorinated hyperbranched linear long-chain segment poly(amide-imide)s were prepared. Subsequently, a detailed comparative study of the optical properties of the hyperbranched PAI films with those of commercial films was carried out.

Morphosyntactic analysis of surigaonun: “Martsa Surigao”

This paper argued that Surigaonun morphosyntactic linearity is revealed in the textuality of Ellen Amores’ “Martsa Surigao”. The knowledge of the structure of Surigaonun language plays significant role in language learning, comprehension, formation of phrases, clauses and sentences, and effective communication using the language. Surigaonun language has no established pedagogic grammar, and there is no research conducted yet on the morphology and syntax of Surigaonun language using textuality. This study aimed to describe the morphosyntactic characteristics of Surigaonun language by analyzing the text “Martsa Surigao” to generate linguistic data on the Surigaonun word structure, the very basis for the morphemic structure of the words, which make up the constituents of the sentence. This qualitative research used the discourse analysis. Specifically, it focused on raw data idealization, morphological analysis, and syntactic analysis on immediate constituents and rewrite rules for each syntactic unit. The linear morphologic segmentation of morphemic contents of “Martsa Surigao” reveals 39 lexical phonemes of 13 simple forms and 26 complex forms; 21 grammatical morphemes of 4 prepositions, 9 pronouns, 5 conjunctions, and 3 determiners. The linear structuration of the textuality in idealized syntactic units reveals 12 simple sentences, 1 compound sentence, and 1 complex sentence according to form. Syntactically, Surigaonun sentences always begin with the predicate and end with the subject as their natural sentence patterning. Sentences are introduced by noun predicates, adjective predicates, adverb predicates, prepositional phrase predicates, intransitive verb predicates and transitive verb predicates. Therefore, the text reveals the morphosyntactic segmentation linearity in its textuality.

Estimation of the Three Phases by Direct Cost of Care for Non-surviving Patients with Cancer: A National Population-based Patient-level Study.

Background: Determining the cost structure of medical care from diagnosis to the death of patients with cancer is crucial for establishing budgets to support patients with cancer. The breakdown of the cost estimation in distinct phases of survival is essential for optimizing the allocation of limited funds. Therefore, this study aims to examine the patterns of direct medical costs of cancer care associated with seven major cancer types and estimate cost thresholds to distinguish each phase based on the incurred cost. Methods: In this nationwide, population-based study, we used claims data from the National Health Insurance Service, Korea. Patients newly diagnosed with cancer since 2006 and who died in 2016-2017 were enrolled, and their use of medical services during cancer survival from at least 6 months up to 12 years was observed. The monthly cost exhibited a non-linear function with two unknown thresholds resembling a U-shape; therefore, we fitted three linear segment models. Individual costs were assessed by dividing the survival time into the initial, continuing, and terminal phases by estimated thresholds, and the average medical cost for each phase was calculated. Results: Based on survival durations of 12 years or less, the initial phase occurred within 1.1-4.8 months after diagnosis, while the terminal phase was observed in 1.4-4.7 months before death. The length of these two phases increased with the increased survival time of the patients. Medical costs in these phases ranged from $4067-7431 and $3127-6114 (US dollars), respectively, regardless of the variations in survival time. However, the average costs in the continuing phase were higher for patients with a short survival time. Conclusions: This study highlights the cost dynamics in cancer care through a breakdown of the phases of survival. It suggests that through a more refined definition of the initial and terminal phases, the average cost in these stages increases, indicating the significant implications of the findings for resource allocation and tailored financial support strategies for patients with cancer with varying prognoses.

Plant Waste Drying in an Isothermal Model

The paper highlights advantages of using furnaces for processing vegetable waste, including the absence of condensation, minimal ash production, stable coolant temperature, and efficient heat exchange. To improve this machine and intensify the drying process, it is necessary to gather data on the heat and mass transfer characteristics during high-temperature drying of moisture-laden particles. Due to the inherent challenges of studying the drying process in a real furnace, the experiment was conducted using an isothermal (cold) model under laboratory conditions closely resembling real-world processes. (Research purpose) The research aims to assess the effectiveness of the proposed aerodynamic models for drying plant waste and validate the mathematical model for drying particles in a suspended bed. (Materials and methods) The study employs two suspended bed models with distinct vortex flow aerodynamics (flare and cyclone) in combustion chambers. The study investigates the drying kinetics of two specific fractions of sunflower husks, each with an equivalent particle diameter of 0.25 and 1.5 millimeters, and initial moisture levels of 15 and 18 percent. At various time intervals, measurements were taken for both the temperature and humidity of the husk particles, in addition to recording the temperature and relative humidity of the drying agent as it exited. The drying process operated in a cyclical mode. (Results and discussion) When the sunflower husk particles had an initial moisture content of 15 percent, two phases of increasing drying rates were observed, while at an 18 percent moisture content, three such periods were identified, with the first period displaying a constant rate. The results suggest that when the husks start with an initial moisture content of 15 percent, the drying curves exhibit minimal linear segments. This observation implies that the process is occurring as the drying rate decreases. (Conclusions) The experiment reveals the most effective drying mode in terms of intensity. It becomes evident that both the flarevortex and cyclone-vortex aerodynamic modes facilitate particle drying, with the cyclone-vortex mode delivering a notably more intense drying process. When transitioning from a model to a real-world process, it is essential to undertake a comparison of estimated processes with practical operational conditions, as exemplified by the particle drying model in a suspended bed.

Toolpath smoothing with reduced curvature and synchronized motion for hybrid robots

G01 commands are the most commonly used toolpath format in Computer Numerical Control (CNC) machining. Due to the discontinuity between adjacent linear segments, toolpath smoothing is necessary to improve machining efficiency and machined surface quality. This paper proposes an analytical C3 continuous local toolpath smoothing and synchronization method for a five-axis hybrid robot. Position and orientation smoothing are decoupled, with quintic B-spline segments replacing the original linear segments. The curvatures of the toolpath are reduced under constrained smoothing errors by weaving transition splines along the linear segments instead of confining them within the corners. A synchronization method based on arc length parameterization tailored to the smoothing method is also proposed. Tool tip position and tool axis orientation are synchronized using another monotonic, C3 continuous spline, which achieves smoother joint motion along the toolpath. For the hybrid robot with highly nonlinear kinematics, improved results in feedrate scheduling considering joint constraints can be realized. Simulations and experiments validate the effectiveness of the proposed method.

Decreases in Employer Referrals to First-Time Substance Use Treatment for Adults From 2004 to 2020.

The aim of the study is to examine trends of employer/employee assistance program referred admissions to outpatient substance use disorder (SUD) treatment in the United States. The publicly available Treatment Episode Data Set was used. Full-time employed adults with no history of SUD treatment referred to outpatient treatment by an employer/employee assistance program from 2004 to 2020 were included ( N = 36,142). Joinpoint regression examined admission trends. Employer/employee assistance program referred admissions to outpatient treatment decreased annually by 6.4% from 2004 to 2020 ( P < 0.001). Joinpoint analyses identified 2 linear segments from 2004 to 2008 (increased but not significant) and from 2008 to 2020. From 2008 to 2020, an average annual percent decrease of 8.7% ( P < 0.001) was identified. Findings from this repeated cross-sectional study suggest a missed opportunity for workplaces to serve as a potential SUD treatment access point.

Untangling Irregular Actin Cytoskeleton Architectures in Tomograms of the Cell with Struwwel Tracer.

In this work, we established, validated, and optimized a novel computational framework for tracing arbitrarily oriented actin filaments in cryo-electron tomography maps. Our approach was designed for highly complex intracellular architectures in which a long-range cytoskeleton network extends throughout the cell bodies and protrusions. The irregular organization of the actin network, as well as cryo-electron-tomography-specific noise, missing wedge artifacts, and map dimensions call for a specialized implementation that is both robust and efficient. Our proposed solution, Struwwel Tracer, accumulates densities along paths of a specific length in various directions, starting from locally determined seed points. The highest-density paths originating from the seed points form short linear candidate filament segments, which are further scrutinized and classified by users via inspection of a novel pruning map, which visualizes the likelihood of being a part of longer filaments. The pruned linear candidate filament segments are then iteratively fused into continuous, longer, and curved filaments based on their relative orientations, gap spacings, and extendibility. When applied to the simulated phantom tomograms of a Dictyostelium discoideum filopodium under experimental conditions, Struwwel Tracer demonstrated high efficacy, with F1-scores ranging from 0.85 to 0.90, depending on the noise level. Furthermore, when applied to a previously untraced experimental tomogram of mouse fibroblast lamellipodia, the filaments predicted by Struwwel Tracer exhibited a good visual agreement with the experimental map. The Struwwel Tracer framework is highly time efficient and can complete the tracing process in just a few minutes. The source code is publicly available with version 3.2 of the free and open-source Situs software package.

On drilling speed of London Clay from MWD data with time-series algorithm for ground characterisation

The ground conditions around an old tunnel in London Clay strata were extensively studied. The correlation between ‘measurement while drilling’ (MWD) drilling parameters and drillhole investigation results, however, was not satisfactory due to the significant noise in the drilling speed. In this paper the original MWD data published in the literature are re-examined and the associated noise issue is addressed by transferring the data in depth series into the data in time series. The curve of the drill-bit advancement depth with net drilling time can be visually divided into many linear segments. Each linear segment has a gradient or constant drilling speed and represents a homogeneous geomaterial zone with constant resistance to drill-bit loading. The depth variation of the constant drilling speed zones is further compared and well verified with the depth variation of lithological strata units identified from rotary-cored samples. A strength grade system is also proposed based on the linear zoning results. A new rock quality designation is calculated from the thickness of the zone of constant drilling speed for the London site and is compared with those at four other sites; this further enhances the understanding and confidence in the linear zoning result and the constant drilling speeds as resistant strengths associated with the lithological strata units in London Clay.

Efficient Navigation and Motion Control for Autonomous Forklifts in Smart Warehouses: LSPB Trajectory Planning and MPC Implementation

The rise of smart factories and warehouses has ushered in an era of intelligent manufacturing, with autonomous robots playing a pivotal role. This study focuses on improving the navigation and control of autonomous forklifts in warehouse environments. It introduces an innovative approach that combines a modified Linear Segment with Parabolic Blends (LSPB) trajectory planning with Model Predictive Control (MPC) to ensure efficient and secure robot movement. To validate the performance of our proposed path-planning method, MATLAB-based simulations were conducted in various scenarios, including rectangular and warehouse-like environments, to demonstrate the feasibility and effectiveness of the proposed method. The results demonstrated the feasibility of employing Mecanum wheel-based robots in automated warehouses. Also, to show the superiority of the proposed control algorithm performance, the navigation results were compared with the performance of a system using the PID control as a lower-level controller. By offering an optimized path-planning approach, our study enhances the operational efficiency and effectiveness of Mecanum wheel robots in real-world applications such as automated warehousing systems.

Piecewise linear approximation with minimum number of linear segments and minimum error: A fast approach to tighten and warm start the hierarchical mixed integer formulation

In several areas of economics and engineering, it is often necessary to fit discrete data points or approximate non-linear functions with continuous functions. Piecewise linear (PWL) functions are a convenient way to achieve this. PWL functions can be modeled in mathematical problems using only linear and integer variables. Moreover, there is a computational benefit in using PWL functions that have the least possible number of segments. This work proposes a novel hierarchical mixed integer linear programming (MILP) formulation that identifies a continuous PWL approximation with minimum number of linear segments for a given target maximum error. The proposed MILP formulation also identifies the solution with the least maximum error among the solutions with minimum number of segments. Then, this work proposes a fast iterative algorithm that identifies non necessarily continuous PWL approximations by solving O(S log N) linear programming (LP) problems, where N is the number of data points and S is the minimum number of segments in the non necessarily continuous case. This work demonstrates that tight bounds for the MILP problem can be derived from these approximations. Next, a fast algorithm is introduced to transform a non necessarily continuous PWL approximation into a continuous one. Finally, the tight bounds and the continuous PWL approximations are used to tighten and warm start the MILP problem. The tightened formulation is shown in experimental results to be more efficient, especially for large data sets, with a solution time that is up to two orders of magnitude less than the existing literature.

Nunchaku: optimally partitioning data into piece-wise contiguous segments.

When analyzing 1D time series, scientists are often interested in identifying regions where one variable depends linearly on the other. Typically, they use an ad hoc and therefore often subjective method to do so. Here, we develop a statistically rigorous, Bayesian approach to infer the optimal partitioning of a dataset not only into contiguous piece-wise linear segments, but also into contiguous segments described by linear combinations of arbitrary basis functions. We therefore present a general solution to the problem of identifying discontinuous change points. Focusing on microbial growth, we use the algorithm to find the range of optical density where this density is linearly proportional to the number of cells and to automatically find the regions of exponential growth for both Escherichia coli and Saccharomyces cerevisiae. For budding yeast, we consequently are able to infer the Monod constant for growth on fructose. Our algorithm lends itself to automation and high throughput studies, increases reproducibility, and should facilitate data analyses for a broad range of scientists. The corresponding Python package, entitled Nunchaku, is available at PyPI: https://pypi.org/project/nunchaku.

Donor-acceptor hyperbranched copolyimides contain different linear segment for electrochromic and resistive memory devices

In this work, two hyperbranched copolyimides (O-coPI and F-coPI) were synthesized which the diamine donors in the linear segment contain different substituents. To investigate the effects of substituents in donors on their memory behavior, the corresponding linear polyimides (F-LPI and O-LPI) were also discussed. The devices based on hyperbranched copolyimides exhibited non-volatile write once read many times memory (WORM) behavior, while the devices based on linear polyimides exhibited volatile memory dynamic random-access memory (DRAM) behavior. Polyimides (O-coPI and O-LPI) prepared with methoxy-substituted diamine donors have low switching voltages due to their good electron-donating properties. In addition, O-coPI and O-LPI also exhibit electrochromic properties. Hyperbranched copolyimide O-coPI have higher optical contrast and faster response time than that of linear polyimide O-LPI. This work provides a new direction for the development of multifunctional memory materials.

Digital monitoring of rotary-percussive drilling with down-the-hole hammer for profiling weathered granitic ground

Rock and geotechnical engineering investigations involve drilling holes in ground with or without retrieving soil and rock samples to construct the subsurface ground profile. On the basis of an actual soil nailing drilling for a slope stability project in Hong Kong, this paper further develops the drilling process monitoring (DPM) method for digitally profiling the subsurface geomaterials of weathered granitic rocks using a compressed airflow driven percussive-rotary drilling machine with down-the-hole (DTH) hammer. Seven transducers are installed on the drilling machine and record the chuck displacement, DTH rotational speed, and five pressures from five compressed airflows in real-time series. The mechanism and operations of the drilling machine are elaborated in detail, which is essential for understanding and evaluating the drilling data. A MATLAB program is developed to automatically filter the recorded drilling data in time series and classify them into different drilling processes in sub-time series. These processes include penetration, push-in with or without rod, pull-back with or without rod, rod-tightening and rod-untightening. The drilling data are further reconstructed to plot the curve of drill-bit depth versus the net drilling time along each of the six drillholes. Each curve is found to contain multiple linear segments with a constant penetration rate, which implies a zone of homogenous geomaterial with different weathering grades. The effect from fluctuation of the applied pressures is evaluated quantitatively. Detailed analyses are presented for accurately assess and verify the underground profiling and strength in weathered granitic rock, which provided the basis of using DPM method to confidently assess drilling measurements to interpret the subsurface profile in real time.

A novel tool path smoothing algorithm of 6R manipulator considering pose-dependent dynamics by designing asymmetrical FIR filters

The joint dynamic constraints of robot manipulators are normally set to conservative constant values to meet the dynamic tolerances at different poses, which leads to incomplete utilization of the joint drive capability. To fully utilize the drive capability of joint drives, this paper proposes an asymmetrical finite impulse response (FIR) filter-based tool path smoothing algorithm, which considers the pose-dependent dynamics of the robot with 6 rotational (6R) joints. To analyze the pose-dependent motor drive capabilities, a simplified dynamics model is established by considering both the tangential and joint dynamic constraints. An asymmetrical FIR filter-based tool path smoothing algorithm is also proposed to realize different constraints of the acceleration and the deceleration limits at different positions of the linear segments. The tool tip position and the tool orientation commands are respectively smoothed in the Cartesian coordinate system and spherical coordinate system, with the constraints of the tool path deviations in the task frame. The synchronization of the position and the orientation is realized by adjusting the parameters of FIR filters. The simulation and experimental results show that the proposed algorithm guarantees the corner error tolerances of the tool tip position and the tool orientation. Moreover, the proposed method improves the robot motion efficiency by more than 10 % through the full utilization of the joint drive capability compared with the traditional tool path smoothing algorithm based on symmetrical FIR filters.

Superior TRAIL gene expression and cancer cell apoptosis mediated by highly branched-linear poly(β-amino ester)s

Extensive efforts have been dedicated to enhancing the expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in cancer cells for the development of effective cancer treatments. However, highly safe and efficient delivery of TRAIL gene remains a significant challenge, especially using cationic polymers. Here, a series of highly branched-linear poly(β-amino ester)s (H-LPAEs) are developed through a unique oligomer branching strategy. H-LPAEs exhibit a more uniform distribution of linear segments and branching units, leading to excellent DNA condensation and favorable physicochemical properties of H-LPAE/DNA polyplexes. In SW1353 and BMSC cells, the optimized H-LPAEs, H-LPAEB4−S5−TMPTA, achieves superior gene transfection efficiency of 58.0% and 33.4%, which were 2.5-fold and 2.0-fold higher than that of the leading commercial gene transfection reagent, Lipofectamine 3000. Excitingly, H-LPAEB4−S5−TMPTA mediated 56.7% and 28.1% cell apoptosis in HepG2 cells and HeLa cells highlighting its potential application in cancer gene therapy. In addition, locally administered H-LPAEB4−S5−TMPTA delivered TRAIL DNA to HepG2 xenograft tumors and inhibited tumor growth in vivo. This study not only proposes a novel strategy for synthesizing poly(β-amino ester)s with a unique branched-linear topology but also identifies a promising candidate for highly efficient TRAIL gene transfection.

A model for contact and friction between beams under large deformation and sheaves

This work focuses on the modeling of contact between sheaves and flexible axially moving beams. A two-dimensional beam finite element is employed, based on the absolute nodal coordinate formulation (ANCF) with an improved selective reduced integration for the virtual work of elastic and viscous damping forces. For the efficient modeling of contact between flexible axially moving beams and sheaves in systems such as belt-drives or reeving systems, a number of newly developed algorithms is presented. The computation of normal contact is based on a penalty formulation using a spring-damper model, while for the efficient contact detection a bounding box which fits the exact dimensions of the finite elements is employed. For the detection and computation of contact, the beam elements are divided into linear segments. The modeling of tangential contact is based on a bristle model for friction extended for being compatible with an implicit time integration. A numerical example of a belt drive showed good convergence and agreement with analytical solutions.

Pseudocatalytic acceleration of hydrothermal leaching of amylose from starch in acidic media

Kinetic studies were conducted at 60–700C using buffer solutions with pH 3–5 to establish the effect of solution acidity on the efficiency of amylose leaching from starch. It was shown that the kinetic data are well described by the Kruger-Ziegler model. It was established that as the pH of the solutions decreases from 5.0 to 3.0, the activation energy of amylose leaching process decreases from 185 to 22 kJ/mol, and its dependence on hydrogen ion concentration is described by two linear segments within the pH ranges of 3.0–3.3 and 3.6–5.0. The effect of reducing the hydrogen bond energy upon addition of an additional proton to the water molecule was demonstrated through quantum-chemical modeling using the Gaussian 09 software. It was shown that protonation of the water molecule leads to a decrease in the effective charge on the oxygen atom from –0.626 to –0.142 unit of electron charge. At the same time, the linearity of the hydrogen bond along the –ОН–О– atoms is violated, the length of the hydrogen bond increases from 1.856 to 2.370 Å, and the binding energy decreases by 4.6 times. Thus, hydrogen ions can be considered as a kind of pseudo-catalyst for the process of amylose leaching from starch grains, since in their presence the activation energy of the process decreases and its rate increases. It was concluded that the process of hydrothermal leaching of amylose from starch can be intensified by carrying it out in acidic media without additional heating of starch suspensions.