Unknown Length Research Articles

Energy coupled–dissipation control for 3-dimensional overhead cranes

Handling loads with small swings is difficult for a 3-dimensional overhead crane due to its hard nonlinearity. Moreover, the nonlinear dynamics increases the complexity of the required feedback, thus making the closed-loop system sensitive to a variation in the cable length that negatively influences the damping feature. To address these problems, a significant storage function characterized by the desired damping is constructed based on passivity. Consequently, a nonlinear controller is delivered by enforcing the coupled–dissipation inequality, thus drastically increasing the damping of the closed-loop system. In particular, new coupled–dissipation signals are fabricated to augment the coupling between the trolley movement and the payload sway. Due to its very simple structure that excludes the cable length, the proposed controller is robust to unknown cable lengths and easy to implement. In the frame of the Lyapunov theory, LaSalle’s invariance principle is applied to illustrate the corresponding stability. The effectiveness of the proposed control on improving the system performance is verified through simulation results.

The complete mitogenome of the fairy shrimp Streptocephalus cafer (Lovén, 1847) (Crustacea: Branchiopoda: Anostraca) from an ephemeral pond in Botswana, southern Africa

Fairy shrimps (Anostraca) constitute an important component of seasonally aquatic habitats, but few complete mitochondrial genomes have been published for this group. Here, we report the mitogenome of a common southern African species, Streptocephalus cafer, from Botswana (accession number: MN720104). Low-coverage shotgun sequencing recovered two contigs 15653 bp and 1347 bp in length that are separated by a repetitive region of unknown length within the non-coding control region. The mitogenome’s GC content is 31.80%. Phylogenetic analysis using protein-coding genes confirms the sister taxon relationship of S. cafer with the only other congener whose mitogenome has been reconstructed to date, the Asian S. sirindhornae.

Development of a new hybrid yarn construction from recycled carbon fibres for high-performance composites: Part IV: Measurement of recycled carbon fibre length

Due to the increasing application of carbon fibre–reinforced plastics, the use of recycled carbon fibres can help reduce the tremendous amount of carbon fibre waste growing worldwide. In this context, the processing of longer recycled carbon fibres (>40 mm mean length) into hybrid yarn constructions offers a promising solution. The characterisation of recycled carbon fibre length is essential for textile processes. However, to suit the atypical fibre characteristics of recycled carbon fibres compared to standard natural or man-made-fibres, the development of an adequate measuring technique is required. Investigations on the state of the art suggest that an adapted fibrograph method might pose an appropriate measuring system. Therefore, new test equipment and an alternative image analysing method based on pixel greyscale values were developed. To enable a calibration process, different samples with cut carbon fibre from carded and drafted slivers were intensively tested and compared. In addition, an adapted reference method was investigated by combining single fibre measurement and image processing techniques. In a final step, recycled carbon fibres samples with unknown fibre length were tested. Results proved that the presented measuring system is adequate for the testing of longer recycled carbon fibres in webs or slivers. All measured values were close to the measured reference length values (deviation ±4%).

Should laparoscopy be the initial approach for completion cholecystectomy in recurrent cholecystitis after subtotal cholecystectomy?

Presenter: Ileana Horattas MD | Cleveland Clinic, Akron General Background: Subtotal cholecystectomy has become a widely accepted alternative for patients presented with acute cholecystitis resulting in significant inflammation and anatomic distortion. Recurrent cholecystitis of the remnant gallbladder is an accepted complication of this procedure. International studies have shown completion cholecystectomy to be the definitive management of recurrent cholecystitis. Few investigators in the United States have focused on management of this scenario, and to this point open surgical approach has been recommended. Methods: Cholecystectomies undertaken by one hepatobiliary surgeon over a two-year period from 2017-2019 were reviewed. Cases of patients with previous cholecystectomy who then presented with acute cholecystitis and underwent laparoscopic completion cholecystectomy were compiled and reviewed to determine interval from initial cholecystectomy, operative time, use of intraoperative cholangiography, use of intraoperative indocyanine green (ICG), placement of drain, and total length of hospital stay (LOS). Results: Seven patients met inclusion criteria. The mean interval from initial cholecystectomy was 22 months (range 3-89 months with one patient presenting an unknown length of time from initial operation). Mean operative time was 119 minutes (range 79 minutes to 141 minutes). Five patients had an intraoperative cholangiogram and one case was completed with intraoperative ICG. A drain was left at the completion of three out of seven cases. Average LOS was less than one day (range 0-2) with three patients discharged in good condition post-operative day 0. No patients required an open operation. Conclusion: Laparoscopy is a safe and effective approach to completion cholecystectomy for patients with recurrent cholecystitis that avoids an open surgical procedure.

Simultaneous Localization and Mapping with Unknown Length of Dynamic Line Segment based on Moving Horizon Estimation

Simultaneous Localization and Mapping with Unknown Length of Dynamic Line Segment based on Moving Horizon Estimation

Profound cerebral cooling in an OHCA patient leads to an excellent neurological outcome after >10 h of ventricular fibrillation on eCPR

We here report a 40-year-old patient suffering from OHCA due to toxic drug abuse. Despite an unknown length of no- or slow-flow time on persisting ventricular fibrillation, the argument for the implantation of an ECLS was his juvenile age, lack of co-morbidities and severe hypothermia (26°C). In the following days, despite of a cerebral oedema this patient achieved a complete neurological regeneration without any clinical deficiencies and was discharged 17 days after admission. Even though the routine use of extracorporal life support systems (ECLS) i.e. va-ECMO as part of an eCPR in Out-of-Hospital Cardiac Arrest (OHCA) patients is not yet recommended by the current guidelines, some tertiary care centrers provide good evidence for eCPR therapy in these OHCA patients. The lack of randomized controlled trials confuses this scenario in general but locoregional clinical algorithms and hospital cooperation such as cardiac arrest center networks will help to stratify and guide these patients to the right place at the right time and thereby improve clinical outcome for these patients with normally poor prognosis. This latter is true for those patients selected by clinical parameters such as an initially shockable rhythm, low no-flow time and a successful bystander CPR which favour for an early initiation of an eCPR therapy. Moreover, young age (<65years), pH >7.0 and serum lactat <2 mmol/l support us in our decision making to initiate eCPR treatment in an otherwise complete insecure situation.

Influence of Residual Welding Stresses on the Limit Equilibrium of a Transversely Isotropic Cylindrical Shell with Internal Crack of Any Configuration

We reduce the elastoplastic problem of limit equilibrium of a transversely isotropic cylindrical shell weakened by an internal longitudinal plane crack of any configuration located in the field of residual stresses to the problem of elastic equilibrium of the same shell containing a through crack of unknown length. This problem, in turn, is reduced to a system of nonlinear singular integral equations. We propose an algorithm for the numerical solution of the obtained system together with the conditions of plasticity, boundedness of stresses, and uniqueness of displacements.

Flexural wave propagation analysis of single-walled carbon nanotubes using molecular structural mechanics approach

In the present study, the flexural wave propagation along single-walled carbon nanotubes (SWCNT) is investigated using molecular structural mechanics approach. The dispersion curves associated to the wave propagation characteristics (i.e., phase velocity versus wave number) of (5,5) and (10,10) armchair test tubes are obtained and compared with the results of the Molecular Dynamics (MD), non-local elastic Timoshenko beam model (NT) and non-local Euler beam model (NE). In addition to the advantages of the present approach such as low computational cost against MD technique and its independency to any extra parameters which have to be experimentally evaluated such as unknown length scales in NT and NE methods, the results show good agreement with the MD results, especially at the high wave number (small wavelength) regimes, which the NT and NE techniques fail to achieve an acceptable predictions.

Metatarsophalangeal proportions of Homo naledi

Post-cranial differences between extant apes and humans include differences in the length, shape and size of bone elements relative to each other; i.e. differences in proportions. Foot proportions are influenced by the different functional requirements of climbing and bipedal locomotion. Phalangeal length is generally correlated with locomotor behaviour in primates and there is variation in hominins in relative phalangeal lengths – the functional and evolutionary significance of which is unclear and currently debated. Homo naledi has a largely modern rearfoot (i.e. tarsal skeleton) and midfoot (i.e. metatarsal skeleton). The proximal pedal phalanges of H. naledi are curved, but the relative lengths are unknown, because the phalanges cannot reliably be associated with metatarsals, or in many cases even with ray number. Here, we assess the lengths of the proximal pedal phalanges relative to the metatarsals in H. naledi with resampling from modern human and chimpanzee (Pan troglodytes) samples. We use a novel resampling method that employs two boundary conditions, assuming at one extreme that elements in the sample are associated, and at the other extreme that no elements are associated. The associated metatarsophalangeal proportions from digits 1 and 2 are within the 95% confidence interval of the modern human distribution. However, the associated and unassociated proportions from digits 3–5 fall above the 95% confidence interval of the human distribution, but below and outside of the chimpanzee distribution. While these results may indicate fossil preservation bias or other sample-derived statistical limitations, they potentially raise the intriguing possibility of unique medial versus lateral pedal column functional evolution in H. naledi. Additionally, the relevant associated proportions of H. naledi are compared to and are different from those of H. floresiensis. Both species suggest deep phylogenetic placement so the ancestral condition of the pedal phalanges in the genus Homo remains unclear.
 Significance: 
 
 Modern humans demonstrate straight and relatively short pedal phalanges, whereas H. naledi demonstrates curved phalanges of an unknown relative length. This research analyses the relative length of the proximal phalanges to the metatarsals to determine if naledi has relatively short phalanges similar to modern humans or is distinct from modern humans in both its phalangeal length and curvature.
 This analysis further develops a statistical resampling method that was previously applied to large fossil assemblages with little association between bones.

Classification of affect using deep learning on brain blood flow data

We present a convolutional neural network- and long short-term memory-based method to classify the valence level of a computer user based on functional near infrared spectroscopy data. Convolutional neural networks are well suited for capturing the spatial characteristics of functional near infrared spectroscopy data. And long short-term memories are demonstrated to be good at learning temporal patterns of unknown length in time series data. We explore these methods in a combined layered architecture in order to improve classification accuracy. We conducted an experiment with 20 participants, wherein they were subjected to emotion inducing stimuli while their brain activity was measured using functional near infrared spectroscopy. Self-report surveys were administered after each stimulus to gauge participants' self-assessment of their valence. The resulting classification using these survey labels as ground truth provided a three-class classification accuracy 77.89% in across subject cross-validation. This method also shows promise for generalization to other classification tasks using functional near infrared spectroscopy data.

Psychosocial Support in Children Victims of Mount Sinabung Eruption

The eruption of Mount Sinabung in Tanah Karo, North Sumatera, which occurred in November 2013 has caused some people to evacuate to avoid the risk of greater disaster. The eruption produced psychological impacts not only on the parents but also on the children, due to the disruption of life activities, radical life changes and living with other citizens, in unknown length of time. Based on the situation, the Faculty of Psychology, University of Sumatra Utara as part of the USU’s Sinabung Task Force took the initiative to serve the people affected by the eruption of Sinabung, especially the children in the form of Psychosocial Support for Children Victims of Sinabung Eruption activities. The activities performed was psychoeducation and psychological assistance. Psychoeducation assistance was provided in the form of training for trainers (TOT) for 15 people from community cadres in Sinabung, while child psychological assistance was done in the form of trauma healing activity in 250 children in evacuation. This services resulted in cadres and children getting their spirits back to focus on the purpose of life they must achieve with their current limitations, more calm, less stress level, more excited, and feel motivated to go back to life with hope for a better future still exist.

Energy-Based Nonlinear Adaptive Control Design for the Quadrotor UAV System With a Suspended Payload

In this paper, the control problem for an underactuated quadrotor unmanned aerial vehicle (UAV) with a suspended payload is investigated. An energy-based nonlinear controller is proposed that is able to control the quadrotor UAV's position and the payload's swing angle asymptotically. An adaptive control design is developed to compensate for the unknown length of the cable which is used to connect the UAV and the payload. The Lyapunov-based stability analysis is employed together to prove the stability of the closed-loop system. Detailed real-time experimental results illustrate the good performance of the proposed controller.

Accurate estimation of fish length in single camera photogrammetry with a fiducial marker

Abstract Videogrammetry and photogrammetry are increasingly being used in marine science for unsupervised data collection. The camera systems employed are complex, in contrast to “consumer” digital cameras and smartphones carried by potential citizen scientists. However, using consumer cameras in photogrammetry will introduce unknown length estimation errors through both the image acquisition process and lens distortion. This study presents a methodology to achieve accurate 2-dimensional (2-D) total length (TL) estimates of fish without specialist equipment or proprietary software. Photographs of fish were captured with an action camera using a background fiducial marker, a foreground fiducial marker and a laser marker. The geometric properties of the lens were modelled with OpenCV to correct image distortion. TL estimates were corrected for parallax effects using an algorithm requiring only the initial length estimate and known fish morphometric relationships. Correcting image distortion decreased RMSE by 96% and the percentage mean bias error (%MBE) by 50%. Correcting for parallax effects achieved a %MBE of −0.6%. This study demonstrates that the morphometric measurement of different species can be accurately estimated without the need for complex camera equipment, making it particularly suitable for deployment in citizen science and other volunteer-based data collection endeavours.

Fast sampling of parameterised Gaussian random fields

Gaussian random fields are popular models for spatially varying uncertainties, arising for instance in geotechnical engineering, hydrology or image processing. A Gaussian random field is fully characterised by its mean function and covariance operator. In more complex models these can also be partially unknown. In this case we need to handle a family of Gaussian random fields indexed with hyperparameters. Sampling for a fixed configuration of hyperparameters is already very expensive due to the nonlocal nature of many classical covariance operators. Sampling from multiple configurations increases the total computational cost severely. In this report we employ parameterised Karhunen–Loève expansions for sampling. To reduce the cost we construct a reduced basis surrogate built from snapshots of Karhunen–Loève eigenvectors. In particular, we consider Matérn-type covariance operators with unknown correlation length and standard deviation. We suggest a linearisation of the covariance function and describe the associated online–offline decomposition. In numerical experiments we investigate the approximation error of the reduced eigenpairs. As an application we consider forward uncertainty propagation and Bayesian inversion with an elliptic partial differential equation where the logarithm of the diffusion coefficient is a parameterised Gaussian random field. In the Bayesian inverse problem we employ Markov chain Monte Carlo on the reduced space to generate samples from the posterior measure. All numerical experiments are conducted in 2D physical space, with non-separable covariance operators, and finite element grids with ∼104 degrees of freedom.

Constraints on the nature of the effusive volcanic eruptions that incised Ravi Vallis, Mars

Ravi Vallis is a Martian outflow channel that is widely interpreted as a product of one or more catastrophic outbursts of groundwater from adjacent Aromatum Chaos. However, solar system analogs are unknown for formation of large channels by outbursts from aquifers, and the Ravi Vallis region lacks the obvious sedimentological and mineralogical signatures expected of aqueous origins. Instead, the basic nature of this channel system is consistent with volcanic origins involving voluminous effusions of low-viscosity lavas. On bedrock slopes of only 0.2°, 50-m-deep lava flows with viscosities of 1 Pa s are predicted to have been characterized by discharge rates of ∼3 × 107 m3/s for 25-km-wide flows, with associated mechanical incision rates of ∼4 m/day and thermal incision rates of ∼2 m/day. Formation of Aromatum Chaos and the preserved 215-km-long extent of Ravi Vallis is conservatively estimated on the basis of thermal considerations to have required eruption of a minimum of ∼64,000 km3 of lava, but greater volumes would have been necessary to form the original (unknown) length of this channel system. A volcanic origin for Ravi Vallis is consistent with development of all Martian outflow channels by igneous processes, and with the broader premise that early development of immense volcanic channel systems is typical of all large rocky bodies.

Unknown-Length Handwritten Numeral String Recognition Using Cascade of PCA-SVMNet Classifiers

Automatic recognition of handwritten digit string with unknown length has many potential real applications. The most challenging step in this problem is how to efficiently segment connected and/or overlapped digits exhibited in the input image. Most existing numeral string segmentation approaches combine several segmentation hypotheses to handle various types of connected digits. This paper proposes a new handwritten digit string recognition without applying any explicit segmentation techniques. The proposed method uses a new cascade of hybrid principal component analysis network (PCANet) and support vector machine (SVM) classifier called PCA-SVMNet. PCANet is an emerging unsupervised simple deep neural network typically with only two convolutional layers. The proposed PCA-SVMNet model adds a new fully connected layer trained separately using SVM optimization method. Cascaded stages of PCA-SVMNet classifiers are constructed and trained to recognize various types of isolated and connected digits. Every PCA-SVMNet classifier is trained separately using combinations of real and synthetic touching digits. The first 1D-PCA-SVMNet stage is trained to recognize isolated handwritten digits (0...9) while forwarding non-isolated digits to the next stages. Each of the following stages is designed to recognize a class of connected digits and forwards the higher class to its successor. Multiple stages can be added accordingly to classify more complex touching digits. The experimental results using NIST SD19 real dataset show that the cascade of PCA-SVMNet classifier efficiently recognizes unknown handwritten digit string without applying any sophisticated segmentation methods. The proposed method achieves state-of-the-art recognition accuracy compared to other segmentation-free techniques.

Single Reference Grid Continuous-Time Formulation for Batch Scheduling

Abstract Short term scheduling of multipurpose batch processes has received growing attention over past decades. It concerns the optimal allocation of a set of limited resources to tasks over time in order to enhance the revenue of plants. This paper addresses the short term scheduling of batch processes through a continuous-time mixed integer linear programming (MILP) formulation based on the state-task network (STN) representation that allows to consider multiple intermediate due dates for market requirements. The proposed formulation can be classified as a slot-based approach that views the time horizon as a set of ordered blocks of unknown and variable lengths. Compared to previous similar approaches, it is simpler and leads to a smaller mathematical model without decoupling tasks from units. A few benchmark problems are used to illustrate the computational advantages of the proposed optimization approach.

Supply Chain Disruptions and Causal Outcomes: Evidence from the Bankruptcy of Hanjin Shipping

Problem: How do supply chain disruptions in the form of unanticipated inventory delays affect firms' inventory holdings? Methodology: I exploit the bankruptcy announcement of Hanjin Shipping in 2016 as an exogenous shock to the global flow of inventory. This announcement stranded \$14 billion of cargo in transit as ports refused to unload Hanjin vessels. As a result, cargo on Hanjin vessels were rendered inaccessible out in the open sea for an unknown length of time. I use a novel dataset featuring tens of millions of sea-based imports from U.S. Customs to identify the: (1) identity of impacted firms, (2) magnitude of experienced cargo delays, and (3) monetary value of delayed cargo. Using a matched difference-in-differences approach, I estimate the impact of this supply chain disruption on firms' inventory holdings. Results: Impacted firms exhibit persistent increases to their inventory holdings, despite having similar pre-disruption inventory levels with their matched counterparts. Specifically, impacted firms increase inventory holdings by 4.6 percentage points on average, and the effect size increases monotonically with the realized length of delay, cargo value, and liquidity. Relevance: I provide causal estimates from a single supply chain disruption, which may help practitioners and academics better understand and manage supply chain risk. Managerial Implications: Supply chain disruptions can delay, degrade, and even destroy inventory. In addition, they can also inflict uncertainty to the flow of inventory, which can cause costly increases to firms' inventory holdings.

Explosive Asset Price Bubble Detection with Unknown Bubble Length and Initial Condition

AbstractRecent research has proposed a method of detecting explosive processes that is based on forward recursions of OLS, right‐tailed, Dickey–Fuller [DF] unit root tests. In this paper, an alternative approach using GLS DF test statistics is considered. We derive limiting distributions for both mean‐invariant and trend‐invariant versions of OLS and GLS‐based Phillips, Wu and Yu (2011, International Economic Review 52, 201–226) [PWY] test statistics under a temporary, locally explosive alternative. These limits are shown to be dependent on both the value of the initial condition and the start and end points of the temporary explosive regime. Local asymptotic power simulations show that a GLS version of the PWY statistic offers superior power when a large proportion of the data is explosive, but that the OLS approach is preferred for explosive periods of short duration as a proportion of the total sample. These power differences are magnified by the presence of an asymptotically non‐negligible initial condition. We propose a union of rejections procedure that capitalizes on the respective power advantages of both OLS and GLS‐based approaches. This procedure achieves power close to the effective envelope provided by the two individual PWY tests across all settings of the initial condition and length of the explosive period considered in this paper. These results are shown to be robust to the point in the sample at which the temporary explosive regime occurs. An application of the union procedure to NASDAQ prices confirms the empirical value of this testing strategy.

Free and Moving Boundary Problems of Heat and Mass Transfer

Bisection method is used to solve a moving boundary problem. This moving boundary problem was solved by the maze of mathematical manipulations by several authors. The method of using bisection is simple as compared to the lengthy mathematical manipulation of other methods. The procedure of the paper is useful in other moving boundary problems of heat and mass transfer, including boundary value problems involving ordinary differential equations with unknown interval length.