Extensive Operations Research Articles

Linear Hahn-Banach type extension operators in Banach algebras of operators

Linear Hahn-Banach type extension operators in Banach algebras of operators

PPIExp: A Web-Based Platform for Integration and Visualization of Protein-Protein Interaction Data and Spatiotemporal Proteomics Data.

Integrating spatiotemporal proteomics data with protein-protein interaction (PPI) data can help researchers make an in-depth exploration of their proteins of interest in a dynamic manner. However, there is still a lack of proper tools for the biologists who usually have few programming skills to construct a PPI network for a protein list, visualize active PPI subnetworks, and then select key nodes for further study. We propose a web-based platform named PPIExp that can automatically construct a PPI network, perform clustering analysis according to protein abundances, and perform functional enrichment analysis. More importantly, it provides multiple effective visualization interfaces, such as the interface to display the PPI network map, the interface to display a dendrogram and heatmap for the clustering result, and the interface to display the expression pattern of a selected protein. To visualize the active PPI subnetworks in specific space or time, it provides buttons to highlight the differentially expressed proteins under each condition on the network map. Additionally, to help researchers determine which proteins are worth further attention, PPIExp provides extensive one-click interactive operations to map node centrality measures to node size on the network and highlight three types of proteins, that is, the proteins in an enriched functional term, the coexpressed proteins selected from the dendgrogram and heatmap, and the proteins input by users. PPIExp is available at http://www.fgvis.com/expressvis/PPIExp .

Non-contact fatigue crack detection in civil infrastructure through image overlapping and crack breathing sensing

Abstract Fatigue cracks are of critical structural safety concern in civil infrastructure. Many existing fatigue crack sensing methods are contact-based, hence extensive human operation is necessary for sensor and/or actuator deployment. In this study, we propose a vision-based non-contact approach to detect fatigue cracks through image overlapping. We treat crack breathing behavior, the small cyclic movement of the crack perpendicular to the crack path under repetitive fatigue loads, as a robust indicator for crack identification. The differential image features provoked by a breathing crack can be extracted, enhanced, and visualized through a series of image processing techniques. The performance of the proposed approach is experimentally validated through two laboratory setups including a small-scale steel compact specimen and a large-scale bridge to cross-frame connection specimen. Test results demonstrate the capability of the proposed approach in reliably identifying the fatigue crack, even the true crack is surrounded by other non-crack features.

Review: perspectives on renal and visceral protection during thoracoabdominal aortic aneurysm repair.

Open repair of a thoracoabdominal aortic aneurysm (TAAA) is an extensive operation and associated with significant perioperative morbidities and mortality, in large part due to distal aortic ischemia secondary to aortic cross-clamping that is necessitated during repair. Distal aortic ischemia may manifest as complications of the kidneys and viscera. Postoperative renal complications range from temporarily elevated levels of creatinine resulting from impaired kidney function to acute renal failure necessitating dialysis that may persist after hospital discharge. Continued advances in the management and adjuncts associated with TAAA repair since the groundbreaking era of E.S. Crawford have led to improved postoperative outcomes following surgery, but the dramatic improvements seen in reducing rates of spinal cord deficits, mesenteric ischemia and other serious postoperative complications have not been seen in contemporary rates of postoperative renal failure. We provide an overview of the various surgical techniques and adjuncts as they relate to the management of visceral and renal ischemia.

Linear extensions of Baire-alpha functions

In this paper, we extend the main result on linear extensions of some Baire-one functions, obtained recently by W. Sieg, to a larger class of Baire functions.Let A be a nonempty subset of a Hausdorff space X, and let α be an ordinal number <ω1. By Bα(X) we denote the space of all real functions X→R of Baire-class-α. F(A) is the set of functions A→R with a property F, such that F(A) is a linear subspace of Bα(A). We prove Borsuk–Dugundji-type extension theorems: we give an explicit form of a linear extension operator T:F(A)→F(X), where A is an Fσ and Gδ-subset of a normal space X. Our results apply for F=to be piecewise continuous, and F=to be of Baire-class-α. We show that T restricted to the subspace of bounded functions from F(A) is a positive isometry with the supremum norm. In particular, this solves partially an extension problem set in 2005 by Kalenda and Spurný.The same technique of proof can be used to obtain similar results for functions with values in separable normed spaces.

Impact of wildfires on Canada's oil sands facilities

Abstract. Exponential growth of oil and gas facilities in wildlands from one side and an anticipated increase of global warming from the other have exposed such facilities to an ever-increasing risk of wildfires. Extensive oil sands operations in Canadian wildlands, especially in the province of Alberta, along with the recent massive wildfires in the province, require the development of quantitative risk assessment (QRA) methodologies which are presently lacking in the context of wildfire-related technological accidents. The present study is an attempt to integrate Canadian online wildfire information systems with current QRA techniques in a dynamic risk assessment framework for wildfire-prone process plants. The developed framework can easily be customized to other process plants potentially exposed to wildfires worldwide, provided that the required wildfire information is available.

Posterior "Open Book" approach for type 1 internal hemipelvectomy.

Internal limb-sparing hemipelvectomy is currently the preferred surgical option for resection of pelvic tumours. Obtaining an acceptable functional outcome through the standard ilioinguinal or iliofemoral incisions, only compounds the already challenging dissection, resection and reconstruction of these extensive en-bloc extirpative oncologic operations. We describe a novel surgical approach to the lateral pelvis that minimises injury to the gluteal muscles, spares the gluteal vessels and provides a broad yet shallow operative field conducive to microsurgery with sizeable vasculature in close proximity to facilitate any microsurgical reconstruction. Access to the ilium and sacrum for Enneking Type 1 and Type 4 resections respectively is obtained by reflecting a skin and soft tissue flap anteriorly while the gluteal muscles are reflected posteriorly and inferiorly. This technique minimises the amount of tissue reflected in any particular direction, therefore, providing a broad and shallow operative field which benefits the orthopaedic oncologic surgeon and the plastic reconstructive surgeon. The "posterior open-book" approach offers a promising alternative to the standard ilioinguinal or iliofemoral incisions for internal limb-sparing Type 1 hemipelvectomies while also optimising the exposure for subsequent reconstructive procedures.

Extension operators and automorphisms

Many of the commonly studied extension operators that take a normalized locally univalent function f defined in the open unit disk D ⊆ C to a normalized locally biholomorphic mapping of the unit ball B ⊆ C n , n ≥ 2 , are of the form f ↦ Ψ ∘ Φ 0 [ f ] , where Φ 0 [ f ] ( z ) = ( f ( z 1 ) , f ′ ( z 1 ) z ˆ ) , z ∈ B , z ˆ = ( z 2 , … , z n ) , is the Roper–Suffridge extension of f and Ψ is a first-coordinate shear, an automorphism of C n of the form Ψ ( w ) = ( w 1 + g ( w ˆ ) , w ˆ ) , where g : C n − 1 → C is holomorphic and contains no terms of degree 0 or 1 in its Taylor expansion at the origin. Other studies have considered the Roper–Suffridge extension operator with the multiplier f ′ ( z 1 ) replaced by a different expression. Recently, it has been shown that the set of restrictions of automorphisms of C n to B satisfying some geometric property such as convexity or starlikeness is dense in the full respective family of geometric mappings when n ≥ 2 . We study large families of biholomorphic mappings on B generated by automorphisms of C n , abstract generalizations of the Roper–Suffridge extension operator, unitary rotations, and families of locally univalent functions on D . In many cases, families arising from distinct automorphisms will be seen to be disjoint, despite the fact that they contain the restrictions of the respective automorphisms to B and the previously noted density result. Of particular interest given our consideration of more general automorphisms related to extension operators, we show that the compositions of the Roper–Suffridge extension operator with a particular class of first-coordinate overshears, automorphisms of C n of the form Ψ ( w ) = ( h ( w ˆ ) w 1 + g ( w ˆ ) , w ˆ ) for g , h : C n − 1 → C holomorphic and h never 0, extend certain bounded starlike mappings of D to starlike mappings of B . We conclude with several open questions inspired by this work.

Dynamic characterizations of gas–solid flow in a novel multistage fluidized bed via nonlinear analyses

A novel multistage fluidized bed for dry desulfurization was presented for the improvement of a gas–solid flow structure. Experiments based on pressure signal acquisition were performed under extensive operating conditions. To obtain a systematic understanding of flow behaviors in the multistage fluidized bed, we applied nonlinear analysis methods coupled with wavelet decompositions. Some interesting phenomena were observed. The chaotic extent in the enlarged sections of the multistage fluidized bed is more sensitive to gas velocity than the solid circulating rate. In comparison with the traditional conveying section, change in flow behavior was observed in the enlarged section according to the Hurst analysis results. Particle movements including inter-particle, gas–particle and particle–wall dominate dynamic behaviors in the fluidized bed under examined operating conditions. The gas–solid interaction in the enlarged section was more intensive than that in the traditional conveying section. Dynamic comparisons between the lower and upper enlarged sections were also conducted. High similarities at the aspect of variation trend of dynamic characterizations were observed along the bed height of each section.

Systems of holomorphic multivalued projections on complex manifolds

Let M be a submanifold of a connected Stein manifold X . We construct a global system of holomorphic multivalued projections X −→M . In particular, for every locally bounded family F ⊂ O(M ) we get a continuous extension operator F −→ O(X ).

Postoperative pain after spinal surgery in the paediatric population.

Postoperative pain is a major aftereffect of surgery. Especially severe occurs after extensive operations within the spine. The goal of the study was to investigate the laboratory predictive factors of intensive postoperative pain in children undergoing extensive surgery Patients and methods: We recruited 41 children, age median 13 years (IQR:10-15 years) undergoing extensive spine surgery. The subjects were divided into two groups based on the intensity of postoperative pain measured using the 10-point numerical rating scale (NRS), visual analog scale (VAS) or faces pain scale-revised (FPS-R). Patients with a score of 5 or higher were included in the study group and those with NRS of less than 5 were included in the control group. We collected detailed clinical and laboratory data before, during and after surgery. The highest intensity of pain was observed in the first 6 hours after surgery. The postoperative pain was associated with a higher drop in hemoglobin concentration and hematocrit level in peri-operative period (p=0.006 and p=0.019 respectively) as well as higher changes in mean arterial pressure during surgery. Additionally, we found that children with intensive pain had higher total protein concentration after surgery. We reported that the drop in hemoglobin and hematocrit level, fluctuation in mean arterial pressure as well as total protein concentration could be useful prognostic factors of early postoperative pain. < p > < /p >.

New trajectory control method for robot with flexible bar-groups based on workspace lattices

For robot with flexible bar-groups that comprise flexible link, flexible joint and joint clearance, it is difficult to guarantee highly accurate and efficient work. To address this problem, dynamic models of flexible links and flexible joints are studied in this paper, and a comprehensive dynamics model is established by constraints. Based on this comprehensive dynamics model, the comprehensive dexterity is defined by the index functions of condition number, minimum singular and dynamics operand, which can reflect the actual situation. Taking the comprehensive dexterity as the main basis, the novel idea of workspace lattice is put forward, and based on the Fourier transform and the principles of probability and statistics, the workspace lattice of robot system can be obtained. The proposed method is experimentally applied to a light-weight parallel robot, and its feasibility and effectiveness are verified. Moreover, extensive actual operation is performed by the light-weight parallel robot, which demonstrates the adaptive capability and the robustness of the proposed method.

Extended pleurectomy decortication: the current role.

Extended pleurectomy/decortication (EPD) has been formally defined but there remain technical areas of debate between practitioners. This is partly attributable to the relative rarity of this operation which is largely confined to a small number of specialist centres. Nevertheless, there is a widespread acceptance that extended pleurectomy/decortication (P/D) is a realistic and favourable alternative to extrapleural pneumonectomy. There may, however, remain a small number of clinical cases where this more extensive operation may be indicated. Preservation of the lung has widened the selection criteria for this form of radical mesothelioma surgery but there remain important factors to consider when offering extended P/D. In many patients with poorer prognostic factors the less radical operation of video assisted partial pleurectomy may be preferable. However, a randomized trial showed no survival benefit for this operation over simple talc pleurodesis. The future for P/D may also lie in the outcome of the MARS2 randomized controlled trial which will report in the next few years. Meanwhile there is a clinical and ethical dilemma when asked to perform this operation outside of the context of a clinical trial in the face of the lack of high grade evidence. The role of P/D is in one respect expanding but this may be short lived pending the findings of its assessment against non-surgical treatment.

Extension of functions in non-isotropic Nikolskii–Besov spaces and approximation of their derivatives

We consider non- isotropic Nikolskii and Besov spaces with norms defined using `-averaged' moduli of continuity of functions of appropriate orders along the coordinate directions, instead of moduli of continuity of given orders for derivatives along these directions. We construct continuous linear maps from such spaces of functions defined in domains of certain type to the ordinary non- isotropic Nikolskii and Besov spaces on in such a way that these maps are function extension operators. Hence both kinds of spaces coincide on such domains. We also find the weak asymptotics of approximation characteristics related to the problem of recovering the derivative from the values of a function at a given number of points, Stechkin's problem for the differentiation operator, and the problem of width asymptotics for non- isotropic Nikolskii and Besov classes in these domains.

Modeling the groundwater temperature response to extensive operation of ground source heat pump systems: A case study in Germany

Ground source heat pump (GSHP) systems have been considered to be a low-carbon technology to provide heating and cooling for buildings in urban environments. This study focuses on the short-and long-term evolution of groundwater temperature induced by high-density GSHP installations in an urban residential area in Cologne, Germany. Specifically, a 2D heat transport model considering both thermal convection and conduction has been constructed using the finite element simulator OpenGeoSys. The simulated temperature changes within the initial few years were compared to the monitored dataset, while the GSHP heating load and thermal conductivity were calibrated. Subsequently, the validated model was run for 25 years to evaluate the long-term trend of the subsurface temperature. Also, effects of model uncertainties were explored with different simulated scenarios. Results indicate that sufficiently large groundwater flow and a high cooling ratio can effectively mitigate ground cooling. Based on these findings, best and worst-case scenarios were formulated for the studied case and the sustainability of GSHP operation were evaluated accordingly. As an outcome, specific design and operation criteria were proposed for the sustainable utilization of shallow geothermal energy for the heating and cooling of buildings in urban areas.

Time-of-Flight Sensor in a Book Reader System Design for Persons With Visual Impairment and Blindness

This paper integrates a time-of-flight (ToF) sensor to a high-resolution charge-coupled device camera in a new and fully automated book reader design for individuals with visual impairment and blindness. This cost-effective and portable book reader design integrates, in a unique way, a 3-D map extracted by a low-resolution ToF sensor and a high-resolution image as means to correct the page curvature of bound books. This is achieved by a seamless registration process of two imaging modalities, so that the low-resolution ( $160 \times 120$ pixels) depth map accurately reflects the entire book spread as captured by the high-resolution camera ( $3072 \times 2304$ pixels). As part of the automated registration process, the book reader will give the user a warning message if the book is misplaced within its field of view. The reading accuracy is further improved by a mathematical framework formulating the flattening and extension operations, which together optimally dewarp the book spread images. This correction process is resilient to potential misplacement of the book within the book reader platform. The testing phase led to a reading accuracy of over 95%, involving an unprecedented acquisition and processing of 200 pages. A database consisting of all the 200 high-resolution book spread images together with their respective extracted depth maps are made available to the research community for further developments.

On operations of possibilistic belief structures

This paper studies operations on possibilistic belief structures, which are constructed by basic possibility assignments, or equivalently, maxitive belief structures, as a framework for modeling imprecise possibility distributions. Different from Dempster–Shafer structures, it is shown that there is no one-to-one correspondence between basic possibility assignments and their induced upper and lower possibilities. The operations on the set of basic possibility assignments might not induce the operations on their upper and lower possibilities. An operation on basic possibility assignments is called proper if it is also the operation on their upper and lower possibilities. We introduce set operations and point operations on basic possibility assignments. Set operations include intersection, union, complement, difference, projection, marginalization, cylindrical extension, vacuous extension and Cartesian product operations. Point operations include all binary and unary operations. We show that all point operations are proper. For set operations, it is shown that union, projection, marginalization, cylindrical extension, vacuous extension and Cartesian product operations are proper, while intersection, complement and difference operations are not proper. In addition, we study construction of compatible possibility distributions and show that the lower possibility of a basic possibility assignment can be represented by the infinimum of compatible possibility distributions. We also show that the local computation technique can be applied to the computation problem of possibilistic belief structures.

KeggExp: a web server for visual integration of KEGG pathways and expression profile data.

Effective visualization is important for knowledge discovery when analysing expression profile data. However, existing tools for visually integrating expression profile data with KEGG pathway maps lack extensive interactive visualization operations. KeggExp simultaneously presents the pathway map of one pathway, dendrogram and heatmap of the genes in the pathway and scatter map of one gene; and also provides interactive operations for highlighting specific genes on the pathway map, including differentially-expressed genes, co-expressed genes selected from the heatmap and user-input genes. With KeggExp, researchers, including those without programming skills, can take advantage of its interactive operations to determine key genes or pathways when analysing expression profile data. Freely available at http://www.fgvis.com/expressvis/KeggExp/. Language: JavaScript, python; Libraries: D3.js, Rxjs, Angular, Django, Django rest frame work, Scipy. Supplementary data are available at Bioinformatics online.

Mathematical analysis on out-of-sample extensions

Let [Formula: see text] be a data set in [Formula: see text], where [Formula: see text] is the training set and [Formula: see text] is the test one. Many unsupervised learning algorithms based on kernel methods have been developed to provide dimensionality reduction (DR) embedding for a given training set [Formula: see text] ([Formula: see text]) that maps the high-dimensional data [Formula: see text] to its low-dimensional feature representation [Formula: see text]. However, these algorithms do not straightforwardly produce DR of the test set [Formula: see text]. An out-of-sample extension method provides DR of [Formula: see text] using an extension of the existent embedding [Formula: see text], instead of re-computing the DR embedding for the whole set [Formula: see text]. Among various out-of-sample DR extension methods, those based on Nyström approximation are very attractive. Many papers have developed such out-of-extension algorithms and shown their validity by numerical experiments. However, the mathematical theory for the DR extension still need further consideration. Utilizing the reproducing kernel Hilbert space (RKHS) theory, this paper develops a preliminary mathematical analysis on the out-of-sample DR extension operators. It treats an out-of-sample DR extension operator as an extension of the identity on the RKHS defined on [Formula: see text]. Then the Nyström-type DR extension turns out to be an orthogonal projection. In the paper, we also present the conditions for the exact DR extension and give the estimate for the error of the extension.

Subcritical approach to conformally invariant extension operators on the upper half space

In this work we obtain sharp embedding inequalities for a family of conformally invariant integral extension operators. This family includes (among others) the classical Poisson extension operator and the extension operator with Riesz kernel. We show that the sharp constants in these inequalities are attained and classify the corresponding extremal functions. We also compute the limiting behavior at the boundary of the extensions of the extremal functions.