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Nonuniform exponential dichotomy represents the nonuniform hyperbolicity for evolution family. Considerable efforts have been made to the relationship between the existence of nonuniform exponential dichotomies and the admissibility of a pair of function classes. In order to reduce the effect of nonuniformity, most results on this aspect need Lyapunov norms in function classes. However, it is difficult to construct an appropriate Lyapunov norm before the existence of a nonuniform exponential dichotomy is established, which happens in the converse problem from admissibility to dichotomy. In this paper, we prove the relationship without a Lyapunov norm. Then we apply our results to giving the relationship between nonuniform exponential dichotomy and invertibility of a differential mapping on some function spaces.

PurposeThe quality liability of prefabricated components (PCs) is a major issue among key stakeholders. The blockchain-based quality tracking systems are supposed to support a more transparent and trusting quality control process. However, many factors affect the stakeholders' willingness toward the adoption of such quality tracking systems. The purpose of this research is to investigate the key factors that influence the stakeholders' adoption decisions toward the application of the quality tracking system in PCs and develop coping strategies.Design/methodology/approachAn evolutionary game model is established that includes the manufacturer, constructor and developer. Four scenarios of equilibriums and the game's evolutionary stable strategies are analyzed, and the corresponding stability conditions are then obtained. Based on the tripartite game model, two representative projects are used as case studies to simulate how different factors affect the stakeholders' decisions.FindingsFirst, trade-offs between cost and benefits were the most prominent factor in the adoption decision-making. Second, the advancement of technologies would compensate for their immaturity. Third, subsidy and penalty provision of the developer and high-level trust both incentivize the stakeholders to adopt the quality tracking systems.Originality/valueThis research investigates the influence of technology, environment and participant related factors on the adoption decisions of the quality tracking system for PCs and discovered that technology maturity and advancement played an essential role. It is expected that the research findings would be of value to policy makers and project management personnel for better quality control of prefabricated construction.

Motivation: This paper proposes a motion artifact removal (MAR) algorithm and its evaluation method for wearable functional near infrared spectroscopy (fNIRS) system. Methods: Two types of motion artifacts (MAs) and their characteristics have been investigated, and a coarse/fine dual-stage MAR method is proposed, which can remove the MAs with different features and magnitudes to protect the original data from damage. In addition, an evaluation method is also proposed based on the classification of 4 mental tasks, which objectively quantize the performance of the MAR algorithms. Results: With the proposed MAR algorithm, the mental-task classification accuracy increased from 74.73% to 83.70% in average.

It was proved that both the normal hyperbolicity and invariant manifold for a uniformly hyperbolic compact invariant manifold and the invariant manifold for a uniformly hyperbolic noncompact invariant manifold are persistent under small perturbation. In this paper, we weaken the uniform normal hyperbolicity to the nonuniform one and prove that both the nonuniform normal hyperbolicity and invariant manifold for a nonuniformly eventually absolutely normally hyperbolic noncompact invariant manifold are persistent under small perturbation in Banach spaces. Unlike the uniform case, we need infinitely many families of norms to uniformize infinitely many exponential dichotomies correspondingly. We use the approximative exponential dichotomy and the pseudo orbit to overcome the difficulty.

Purpose We aimed to compare treatment efficacy, safety and material cost between tissue gel and coil regarding variceal embolization during transjugular intrahepatic portosystemic shunt (TIPS). Materials & Methods: This retrospective study including cirrhotic patients with variceal bleeding treated with TIPS combined with variceal embolization between January 2016 and August 2017. Patients were divided into three groups according to embolic agents used in variceal embolization: tissue gel group (Group A), combination group (Group B), and coil group (Group C). The primary endpoint was 1-year rebleeding rate after TIPS creation. The secondary endpoints included shunt dysfunction, overt hepatic encephalopathy, liver function, and embolic agents-related expense. Results A total of 60 patients (30, 10, and 20 in Group A, B, and C) were included. Variceal rebleeding occurred in 3 (10%), 0 (0%), and 4 (20%) patients within one year after TIPS creation in Group A, B, and C, respectively. Stent dysfunction occurred in 2 (3.3%) patients and 9 (15.0%) patients experienced overt hepatic encephalopathy. No significant differences were observed between three groups regarding primary and secondary endpoints except embolic agents-related expense, with a significantly lower cost in Group A when compared to the other two groups. Stent dysfunction occurred in two patients, with one patient in Group A developed acute occlusion caused by thrombus and another patient in Group C underwent stent stenosis during follow-up. Conclusions Compares to coil alone or combines with coil, tissue gel has similar treatment efficacy and safety, but with significantly lower cost for variceal bleeding during TIPS.

Objectives: To present a case series of modified transjugular intrahepatic portosystemic shunts (TIPS) and percutaneous transhepatic intrahepatic portosystemic shunts (PTIPS) in cirrhotic patients with variceal bleeding (VB). In addition, the scientific literature pertaining to PTIPS was reviewed. Methods: This retrospective clinical case series included six cirrhotic patients with VB who were treated with PTIPS after the failure of endoscopic band ligation or endoscopic injection sclerotherapy combined with vasoactive drugs. The treatment was conducted between January 2017 and June 2019 at a single institution. Three patients suffered from severe atrophy of the right or left lobar of the liver as well as the main right or left branch of the portal vein. The remaining three patients showed severe atrophy of the whole liver and portal vein, resulting in widening of the liver fissure. A paired t-test was used to compare the changes in portal pressure gradient between before and after the PTIPS operation. The rebleeding rate, treatment efficacy, complications, and technical success rate were all assessed during follow-up. Results: All six PTIPS procedures were performed successfully, with no severe procedural-related complications observed. None of the patients experienced VB during a mean follow-up of 22.8 (range, 18.0–28.0) months. The mean portosystemic pressure gradient decreased from 28.3 ​± ​4.3 ​mmHg pre-procedure to 12.3 ​± ​2.6 ​mmHg immediately post-procedure (P ​

This paper addresses the impact of adding 0.14 wt% of vanadium to a fine-grained DP1300 steel, particularly in terms of damage and ductility. Variants with and without V were heat treated so as to obtain a similar vol% of martensite in the microstructures, and hence both steels had comparable tensile strengths. As a result of the V addition, ferrite grain size was reduced from 4.8 to 2.9 μm in rolling and normal directions in the reference steel to 1.6 and 0.8 μm in the V-added steel, respectively. Consequently, significant ductility improved achieved in the V-added steel. Through this research, we have investigated the influence of V on the mechanical properties of the ferrite and martensite phases, plastic compatibility between ferrite and martensite, and the fracture morphology. The hardness of ferrite and martensite were determined using statistical nanoindentation tests. Microstructural damage was investigated during in-situ tensile tests coupled with scanning electron microscopy followed by fractography. X-ray computed tomography was conducted to quantify microstructural damage and for further analysis of fracture. Results show that adding V to DP1300 leads to grain refinement, microstructural homogenization, enhancement of martensite ductility, and improved mechanical compatibility between ferrite and martensite. Hence, strain is distributed more homogeneously between the two phases in the V-added steel and strain localization is reduced. This helps to suppress the evolution of microstructural damage during post-uniform elongation leading to improved ductility. Dimple-based ductile fracture was dominant accompanied by some quasi-cleavage fracture in both steels and shear fracture was observed in the V-added steel.

Functional near-infrared spectroscopy (fNIRS) is considered as a non-invasive and effective brain-computer interface technology. Wearable high-resolution fNIRS requires a large-scale LED array, which consumes a lot of power, and shorten the battery life. This paper proposes a spatial adaptive sampling (SAS) method that can take advantage of the spatial sparsity of fNIRS devices and greatly reduce the power consumption while maintaining high image quality. To improve the performance of the proposed SAS technique, a low power binary neural network (BNN) is proposed to accurately predict the current brain task. And the optimal dynamic LED pattern for each brain task is investigated. The proposed SAS technique is validate through an off-line experiment, it can reduce the power consumption of the LED array by 62.5% compared to not using SAS technology while maintaining a PSNR (Peak Signal to Noise Ratio) of 33 dB.

As an effective method to reduce the unsafe behavior of construction workers, safety training has always been the hotspot of safety management research. In recent years, while there is an ever-growing research interest on developing effective training techniques and methods, few studies have improved safety training with the targeted interactions with construction workers. Therefore, based on natural language processing technology, this paper introduced the chatbot into construction safety training and designed a framework for personalized construction worker safety training on mobile phones. In particular, the single-round question and answer technique with the chatbot was introduced with an illustrative example. Through word segmentation, part-of-speech tagging, similarity calculation, and threshold comparison, questions and sentences from regulations could be compared to determine which sentence should be chosen as the most matching answer, and to improve workers’ ability to work safely. In this way, this research provided an innovative, adaptive, convenient and knowledge-rich personalized safety training approach, in the hope of reducing cognitive difficulty and increasing learning interests of construction workers.

When Proof-of-Stake (PoS) underlies a consensus protocol, parties who are eligible to participate in the protocol are selected via a public selection function that depends on the stake they own. Identity and stake of the selected parties must then be disclosed in order to allow verification of their eligibility, and this can raise privacy concerns. In this paper, we present a modular approach for addressing the identity leaks of selection functions, decoupling the problem of implementing an anonymous selection of the participants, from the problem of implementing others task, e.g. consensus. We present an ideal functionality for anonymous selection that can be more easily composed with other protocols. We then show an instantiation of our anonymous selection functionality based on the selection function of Algorand.

This paper presents a multichannel functional continuous-wave near-infrared spectroscopy (fNIRS) system, which collects data under a dual-level light intensity mode to optimize SNR for channels with multiple source-detector separations. This system is applied to classify different cortical activation states of the prefrontal cortex (PFC). Mental arithmetic, digit span, semantic task, and rest state were selected as four mental tasks. A deep forest algorithm is employed to achieve high classification accuracy. By employing multigrained scanning to fNIRS data, this system can extract the structural features and result in higher performance. The proposed system with proper optimization can achieve 86.9% accuracy on the self-built dataset, which is the highest result compared to the existing systems.

Relationship between exponential dichotomies and admissibility of function classes is a significant problem for hyperbolic dynamical systems. It was proved that a nonuniform exponential dichotomy implies several admissible pairs of function classes and conversely some admissible pairs were found to imply a nonuniform exponential dichotomy. In this paper we find an appropriate admissible pair of classes of Lyapunov bounded functions which is equivalent to the existence of nonuniform exponential dichotomy on half-lines R ± separately, on both half-lines R ± simultaneously, and on the whole line R . Additionally, the maximal admissibility is proved in the case on both half-lines R ± simultaneously.

We have investigated the effect of vanadium addition on a DP1300 ferrite-martensite steel, particularly in terms of microstructure, deformation, and damage behavior at the microscopic level. DP steels with and without vanadium addition were given slightly altered heat treatments to produce similar martensite content and ultimate tensile strength in both steels. The addition of 0.14wt% vanadium to the reference alloy yields a dispersion of nano-scale vanadium carbonitrides throughout the microstructure along with a pronounced grain refinement. Microscopic digital image correlation (μDIC) was employed to analyze the local strain partitioning between ferrite and martensite at the grain level. It was found that the addition of V increases the mechanical compatibility between ferrite and martensite. The consequent enhanced mechanical homogeneity and reduced strain gradients at the ferrite-martensite interface suppresses damage, thus enhancing ductility of the V-added alloy. Interrupted tensile tests coupled with X-ray computed tomography confirm that microstructural damage growth is slower in the V-added steel during post-uniform elongation prior to fracture.

In this short note, we verify R. Bryant's claim: there does exist the singular Landsberg Finsler surface with a vanishing flag curvature which is not Berwaldian.

In this paper, the isoperimetric problem in the 2-dimensional Finsler space form [Formula: see text] with [Formula: see text] by using the Busemann–Hausdorff area is investigated. We prove that the circle centered the origin achieves the local maximum area of the isoperimetric problem.

In this paper we study the roughness of tempered exponential dichotomies for linear random dynamical systems in Banach spaces. Such a dichotomy has a tempered bound and describes nonuniform hyperbolicity. We prove the roughness without assuming their invertibility and the integrability condition of the Multiplicative Ergodic Theorem. We give an explicit bound for the linear perturbation such that the dichotomy is persistent. We also obtain explicit forms for the exponent and the bound of tempered exponential dichotomy of the perturbed random system in terms of the original ones and the perturbations.

In order to achieve the packages with much higher performance, more I/Os, lower profile and lighter weight, the thickness of silicon wafer has been decreased dramatically in recent years, but which degrades the strength of thinned wafer. In this paper, three-point bending test was adopted to evaluate the thinned wafer fracture strength, and the impacts of back-grinding process parameters on the wafer fracture strength were addressed. Results show the trend of an increase in wafer strength with an increase in grinding wheel rotational speed and a decrease in grinding wheel feed rate. Also, it is found that the strength decreases progressively from the center of wafer to the edge for most wafer samples.

The volatilization behavior of rhenium in the process of oxidative roasting of a molybdenite concentrate with 43.55 wt.% Mo and 321 g/t Re is explored based on identifying the relationship between volatilization of sulfur and rhenium. The results show that rhenium volatizes after sulfur and precise control of operating variables plays an important role in separating rhenium from molybdenite concentrate. When the roasting parameters are optimized as follows: roasting temperature 600 °C, roasting time 2 h, roasting atmosphere air, the volatilization rate of rhenium reaches 89.26%. In the process of solidification roasting, the volatilization rate of rhenium decreased almost to zero when the ratio of slaked lime/molybdenum concentrate was 10% excess to the stoichiometric requirement at 600 °C for 2 h.

The effects of microwave roasting on separation of rhenium (Re) and molybdenum (Mo) from a molybdenite concentrate have been investigated based on evaluation of the heating characteristics of the concentrate in the microwave field. The results show that a variety of operating variables, namely microwave power, sample weight, sample geometry, roasting temperature, roasting time and atmosphere significantly impact on the volatilization rates of Re and Mo. The optimum conditions for Re-Mo separation are microwave power 1300 W, sample weight 20 g, sample geometry pellets, temperature 600 °C, time 1.5 h, and atmosphere 20%O2. Under these experimental conditions, the volatilization rate of Re reaches 88.12%, while that of Mo is just 5.15%. Microwave-assisted roasting provides an alternative route to separating Re and Mo from molybdenite concentrate.

In this paper, under the assumption of Gauss curvature vanishing at infinity, we will prove Meeks' conjecture: the number of disjointly supported minimal graphs in $\mathbb{R}^3$ is at most two., 8 pages

In this paper, we give the general form of spherically symmetric Finsler metrics in $R^n$ and surprisedly find that many well-known Finsler metrics belong to this class. Then we explicitly express projective metrics of this type. The necessary and sufficient conditions that projective Finsler metrics with spherical symmetry have constant flag curvature are also obtained.

In this paper, we derive a gradient estimate for the linear combinations of eigenforms of the Hodge Laplacian on a closed manifold. The estimate is given in terms of the dimension, volume, diameter and curvature bound of the manifold. As an application, we obtain directly a sharp estimate for the heat kernel of the Hodge Laplacian., Some comments are added and references are revised

As the number of software vulnerabilities increases, the research on software vulnerabilities becomes a focusing point in information security. A vulnerability could be exploited to attack the information asset with the weakness related to the vulnerability. However, multiple attacks may target one software product at the same time, and it is necessary to rank and prioritize those attacks in order to establish a better defense. This paper proposes a similarity measurement to compare and categorize vulnerabilities, and a set of security metrics to rank attacks based on vulnerability analysis. The vulnerability information is retrieved from a vulnerability management ontology integrating commonly used standards like CVE ( http://www.cve.mitre.org/ ), CWE ( http://www.cwe.mitre.org/ ), CVSS ( http://www.first.org/cvss/ ), and CAPEC ( http://www.capec.mitre.org/ ). This approach can be used in many areas of vulnerability management to secure information systems and e-business, such as vulnerability classification, mitigation and patching, threat detection and attack prevention.

Along with the increasing interest in (h, k)-dichotomy, more attentions are paid to sub-exponential growth in research of asymptotic behaviours. In this paper, we generalize a projected discrete Gronwall's inequality given in [J. Differ. Equ. Appl. 10 (2004), 661–689] to a general one, which may include both terms of sub-exponential growth inside the summation and non-monotonic terms outside the summation. We demonstrate our results with concrete non-monotonic functions and sub-exponential functions. We apply our results to estimating bounded solutions of a non-linear difference equation with an (h, k)-dichotomy.