Invalidation Mechanism Research Articles

Industrial‐Level Modulation of Catalyst‐Electrolyte Microenvironment for Electrocatalytic CO2 Reduction: Challenges and Advancements

AbstractCO2 reduction reaction (CO2RR), as a promising strategy for storing renewable energy and promoting carbon resource recycling, is critical for industrial development. Previous reports have extensively explored catalyst‐electrolyte microenvironmental modulation to elucidate coupling mechanisms and enhance catalytic conversion to multicarbon products. Currently, most reviews mainly focus on the impact of microenvironment modulation in low‐current systems on mechanism exploration and performance optimization, yet few of them can integrate macroscopic applications with microscopic investigations to explore the relevance between industrial development and catalyst‐electrolyte microenvironmental optimization. To address the gap, this review focuses on summarizing the challenges and advancements in microenvironment modulation for the development of high‐current devices. By introducing models of different scales sequentially, the connection between microenvironmental modulation and device performance is clarified. Then, various invalidation mechanisms and effective solutions are summarized to intuitively expound the impact of microenvironment modulation on high‐current stability. Meanwhile, as an intuitive measure of the rationality of microenvironment modulation, evaluation methods of device performance should be refined, which are also covered in further detail below. Finally, more valuable and challenging prospects are discussed for guiding the further industrial transformation of CO2RR.

Study on condensation invalid mechanism of superhydrophobic structure in gravity heat pipes

In order to study the effect of superhydrophobic structure failure on condensation heat transfer and flow in gravity heat pipe, superhydrophobic surfaces with three diameters (D = 10 μm, 15 μm, 20 μm), three heights (H = 19 μm, 22 μm, 25 μm), three angles (α = 75°, 82.5°, 90°) and two spacings (S = 50 μm, 70 μm) were established by means of simulation. The results showed that when the angle of the superhydrophobic structure is 90°, although the superhydrophobic structure fails, the contact angle hysteresis of the liquid film is small, the liquid film renewal cycle can reach 0.108 s at the fastest, and the average temperature of the wall surface is 4.2 % higher than that of the ordinary surface. When the liquid film is pinned to the surface, the temperature is positively correlated with the diameter. When the liquid film renewal period is short, the temperature is negatively correlated with the diameter and height of the structure, and the highest temperature is 284.477 K. When the spacing is 70 μm, there are two droplets in opposite directions between the columns, which is beneficial for droplets to be pulled out of the superhydrophobic structure columns, showing the wetting state of Cassie, and effectively correcting the occurrence of superhydrophobic failure. The research results provide a reference for the application of superhydrophobic structure in heat pipes.

Photocatalytic mechanisms and photocatalyst deactivation during the degradation of 5-fluorouracil in water

Photocatalytic oxidation and micropollutants have both attracted extensive attention in the field of wastewater treatment. However, invalidation mechanism of photocatalytic system and target transformation are still a challenge. Here, we used TiO2 supported on nickel foam (TiO2/NF) and 5-fluorouracil (5-FU) as model photocatalyst and pharmaceutical micropollutant to investigate photocatalytic transformation pathways of 5-FU and inhibition mechanisms of its degradation efficiency reduction. Incredibly, removal efficiency of 5-FU dramatically decreased from 80% to 20% after 120 h continuous operation, owning to the competition for hydroxyl radical (•OH) between trans-intermediates and 5-FU, accumulated in the solution. Using HR-MS, the produced intermediates during photocatalytic degradation of 5-FU were revealed to be that mono/polyhydroxylated compounds, short-chain oxides and carboxylation ones were main trans-intermediates. Combining ATR-FTIR, SEM-EDS and validation experiments for factors, it was found that the inhibition of 5-FU degradation should be contributed to the competition for •OH in the bulk or preferential consumption of •OH in TiO2 diffusion layer, by the aforementioned intermediates. The present study provides insights into photocatalytic oxidation of 5-FU and basic information about mechanisms of inhibition on target contaminant removal.

Test study on thickness of soil layer at top of plate affecting uplift failure of the NT-CEPP

This paper studies the influence of the thickness of the soil layer on the head of the plate on the carrying capacity of the new type concrete plates-expanded pile (NT-CEPP) under vertical tension, and innovatively uses the half-section pile test method to measure undisturbed soil and ANSYS is used for comparative analysis. Due to the small-scale test based on the half-section pile and disturbed soil, not only can the overall invalidation mechanism of the soil around the pile be seen more clearly, but the undisturbed soil can also be used to better ensure the stability of the soil. At the same time, in the test, depending on the real station under construction, the authenticity and economy of the test should be ensured. The results of test reveal that the invalidation behaviour of the on the top of plate of the NT-CEPP has little effect on the adjacent soil layer when the soil thickness of embedded slab is more than 3 times the length of the cantilever of the slab, and the characteristics of adjacent soil-layer had no influence on the carrying capacity of the plate.

The invalidation mechanism of kinetic hydrate inhibitors under high subcooling conditions

Vinyl lactam-based polymers have been shown to be excellent kinetic hydrate inhibitors (KHIs), inhibiting the formation and growth of methane hydrate under low subcooling conditions. However, under moderate/high subcooling conditions, they lose their inhibitory effect and can even be converted into hydrate promoters. In this work, molecular dynamics simulations were employed to explore the invalidation mechanism of two vinyl lactam-based KHIs, namely, PVP-A and PVP, under high subcooling conditions. By analyzing the nucleation and growth trajectories of methane hydrate in the absence/presence of KHIs, we found that the addition of KHIs could shorten the nucleation time of methane hydrate by reducing the mass transfer resistance of methane and water molecules and accelerating the formation of the hydrate precursor. Additionally, KHIs can facilitate the formation and survival of sII hydrate by improving the kinetic superiority of the methane-water homogeneous solution.

Effective E-Healthcare System

Focus of health care data research has shifted towards configuring and handling e-health information from heterogeneous e-health administration entities in a Content Distribution Network (CDN) for gaining e-health benefits which may be a testing errand. In recent trends, CDNis typically is used to reserve e-health networking substance as ongoing images captured in real time sequences and ongoing videos. In mobile cloud computing, due to patient's movement, it is required for medicinal services professionals to bring information of patient health with quick access of e-health data to make effective choices and select medication. Caching and its invalidation mechanism will provide the solutions in effective e-health data availability. A lot of caching methodologies are proposed, such as the Scalable Asynchronous Cache Consistency Scheme (SACCS) which has demonstrated more versatility over others. In this article, the authors recommend another reserve reinstatement algorithm with SACCS in consideration that is dependent upon rule-based Least Profit Value.

Quantitative invalidation characterization of Portland cement based on BSE and EDS analysis

The degradation of mechanical properties of Portland cement caused by the invalidation of Portland cement is a serious problem that affects the quality of concrete nowadays. However, an effective invalidation characterization method of Portland cement has not been set up. Back scattering electron (BSE) and energy-dispersive spectrometry (EDS) were adopted to quantitatively characterize the invalidation of Portland cement in this study. The EDS results demonstrated that the acicular crystals generated near cement particles in BSE images are ettringites. Therefore the invalidation of Portland cement is mainly caused by the expansive ettringite generated from the hydration of oxides containing Aluminium, and crystallisation corrosion is the main invalidation mechanism. When the microstructure of acicular morphology with a length longer than 3.0 μm is observed from BSE images of Portland cement samples, the cement can be quantified as exhibiting complete invalidation. Meanwhile, the content changing of element in the area of ettringite formation acquired with EDS analysis can also be used to characterize the invalidation of Portland cement. When the content of oxide containing aluminium is not more than 5.0%, the cement is not judged as invalidated; the invalidation of cement will occur once the content of oxide containing aluminium exceeded 5.0%; when the content of oxide containing aluminium exceeded 10.0%, the cement is considered completely invalidated.

Lazy Management for Frequency Table on Hardware-Based Stream Lossless Data Compression

The demand for communicating large amounts of data in real-time has raised new challenges with implementing high-speed communication paths for high definition video and sensory data. It requires the implementation of high speed data paths based on hardware. Implementation difficulties have to be addressed by applying new techniques based on data-oriented algorithms. This paper focuses on a solution for this problem by applying a lossless data compression mechanism on the communication data path. The new lossless data compression mechanism, called LCA-DLT, provides dynamic histogram management for symbol lookup tables used in the compression and the decompression operations. When the histogram memory is fully used, the management algorithm needs to find the least used entries and invalidate these entries. The invalidation operations cause the blocking of the compression and the decompression data stream. This paper proposes novel techniques to eliminate blocking by introducing a dynamic invalidation mechanism, which allows achievement of a high throughput data compression.

Invalidation Method for Wireless Mobile Network to Maintain Consistency

This paper is proposed for the distributed cache invalidation mechanism (DCIM), it is a client-based cache consistency scheme which is implemented on the top of a previously proposed architecture for the caching data items in mobile ad hoc networks (MANETs), namely COACS, where special nodes cache the queries and the addresses of the nodes that store the responses to these queries. Caching frequently accessed data items on the client side is an effective technique for improving performance in a mobile environment. The classical cache invalidation strategies are not suitable for the mobile environments due to frequent disconnections and mobility of the clients. The huge amount of demand has been created due to trend toward wireless communications and advances in mobile technologies are which increasing the consumer demands for ubiquitous access to Internet-based information and services. DCIM can be implemented using ns2, and compared against the client-based and server-based schemes to assess its performance experimentally. Hear introduce DCIM that is totally client-based. DCIM is a pull- based algorithm that implements adaptive time to live (TTL), piggybacking, and pre-fetching, and provides near strong consistency capabilities. Keywordsdata caching, pull-based, TTL, shared data.

User-defined consistency sensitive cache invalidation strategies for wireless data access

In order to fulfill users’ insatiable interests in accessing Internet services and information wirelessly, one of the key optimization techniques is caching frequently accessed data items in a local cache. A strong consistency is implicitly assumed in most caching schemes but it may cause a long query delay. In this paper, we propose a consistency-sensitive cache invalidation scheme, called ConSens, based on the existing Invalidation Report (IR) and Updated IR (UIR) based cache invalidation frameworks. In the ConSens scheme, each user is able to set its own consistency level with a server independently. This user-defined cache consistency can support diverse consistency requirements of applications. We also propose both lazy request and opportunistic data access techniques to effectively balance the data accessibility and query delay. In addition, we enhance the IR-based cache invalidation mechanism and propose a multiple data transmission scheme, called MDT, to further reduce the query delay. Extensive performance evaluation studies show that the proposed strategies can effectively balance the data accessibility, reduce the query delay, and significantly increase the number of opportunistic accesses according to the user-defined consistencies.

Zhang et al. reply

replying to J. Luo et al. , 10.1038/nature12589 (2013). We agree with Luo et al.1 that the magnetoresistance effects that we reported2 were dependent on the method used to measure them. The reason that there is a difference in the results depending on whether method 1 or method 2 is used (adopting the measurement notation of ref. 1) is that there are two voltage-stabilizing diodes in the Keithley 2400 instrument we used. We were unaware that when this instrument was used both as current source and voltmeter, one diode connected the input port of the current source to the input port of the voltmeter, whereas the other diode connected the output port of the current source to the output port of the voltmeter. The diodes caused a crossover of the Hall coefficient from negative to positive when the instrument was used to conduct a Hall measurement in this configuration, leading us to propose an invalid mechanism for the abnormal magnetoresistance. Therefore the mechanism we proposed2—minority injection and an induced p-n boundary—does not provide a correct explanation for the observed geometry-enhanced magnetoresistance. Although such a mechanism does not operate in our samples, we note that a p–n boundary could still enhance magnetoresistance in certain circumstances according to our and others’ theoretical calculations and experiments2,3,4.

DCIM: Distributed Cache Invalidation Method for Maintaining Cache Consistency in Wireless Mobile Networks

This paper proposes distributed cache invalidation mechanism (DCIM), a client-based cache consistency scheme that is implemented on top of a previously proposed architecture for caching data items in mobile ad hoc networks (MANETs), namely COACS, where special nodes cache the queries and the addresses of the nodes that store the responses to these queries. We have also previously proposed a server-based consistency scheme, named SSUM, whereas in this paper, we introduce DCIM that is totally client-based. DCIM is a pull-based algorithm that implements adaptive time to live (TTL), piggybacking, and prefetching, and provides near strong consistency capabilities. Cached data items are assigned adaptive TTL values that correspond to their update rates at the data source, where items with expired TTL values are grouped in validation requests to the data source to refresh them, whereas unexpired ones but with high request rates are prefetched from the server. In this paper, DCIM is analyzed to assess the delay and bandwidth gains (or costs) when compared to polling every time and push-based schemes. DCIM was also implemented using ns2, and compared against client-based and server-based schemes to assess its performance experimentally. The consistency ratio, delay, and overhead traffic are reported versus several variables, where DCIM showed to be superior when compared to the other systems.

The surface morphologies and spectroscopy analysis of VC coatings on the substrate of Cr12MoV prepared by TD process after salt spray

The normal temperature corrosion of VC coating on the substrate of Cr12MoV prepared by TD process was tested in 5% NaCl aqueous solution, its surface morphologies and corrosion components after salt spray were observed with SEM and EDS, respectively, and the effects of salt spray on micro-structures of VC coating were analyzed. Moreover, the invalidation mechanism of VC coating after salt spray and its effect on substrate material were discussed. The experimental results shown that the uniformity and integrity of VC coating surface are destroyed by salt spray for 120 h, a large number of the pits are produced on the coating surface, and the coating falls off, which speeds corrosion breakage of its substrate; the oxidated film on its surface becomes rougher, broken and discontinuous, and falls off easily, which reduce the ability of resistance salt spray; the failure modes of VC coating after salt spray are expressed with falling off of oxidated film, stress concentration and pore effect and so on, the corrosion breakage of oxidated fi lm is the corrosion result of deoxidization corrosion from oxygen and HCl produced by NaCl and vapor.

Optimization of Self-organization Model of Electronic Connector under Fretting Wear Based on Taguchi Method

The self-organization model of an electronic connector under fretting wear is studied to explain the invalidation mechanism in fretting wear driven by integrating local rules. The electronic connector under fretting wear is the object to be studied. In order to confirm the local rules of self-organization model of fretting wear and their parameters,Taguchi method is proposed to optimize the self-organization model of an electronic connector under fretting wear. Taguchi method is applied to set up a dominant relationship between the self-organization rules and evaluation function quantitatively. That is to say,the experimental data of an electronic connector under fretting wear is regarded as the evaluation function. And Taguchi method is used to design and solve the simulation of unknown parameters in an integrated rule of the cellular automata model. Thus,from a high quality self-organization model,the invalidation mechanism of an electric connector can be expressed in high precision. Meanwhile,the study and practice on the subject shows that Taguchi method is an effective and simple tool to solve the complicated system based on the integration of a bottom-up self-organization theory and a top-down planning theory.

The invalidation mechanism of bolt-mesh support in soft coal roadway

The bolting is easy to go out of force in soft coal roadway. Based on the field measured data, the reason of bolt pre-stressed hysteresis descending in soft coal roadway was analyzed in detail by theoretical analysis and field measurement. Closely encircling the changing law of anchorage force during the bolt bearing course, the reason of the low initial anchorage force in soft coal roadway, the effect of surrounding rock deformation on bolt anchorage force and the circulating hysteresis descending of anchorage force as well as the impact of the structure stability on bearing structure of the bolt-mesh support were analyzed. The analyzed results show there exists a great amount of bolt pre-stress hysteresis descending in soft coal roadway because of remarkable difference between bolt and soft coal deformable capability. Thus, many comprehensive measures should be taken to effectively control the initial loose deformation of non-anchorage rocks between two bolts, to achieve higher initial anchorage force and to prevent anchorage force losing during bolt bearing course. At the same time along with increasing the bolting strength, the structure compensating measures should be taken to ensure the structure stability of the bolt-mesh support and to realize the high-strength stable bolting.

InvisiFence

A multiprocessor's memory consistency model imposes ordering constraints among loads, stores, atomic operations, and memory fences. Even for consistency models that relax ordering among loads and stores, ordering constraints still induce significant performance penalties due to atomic operations and memory ordering fences. Several prior proposals reduce the performance penalty of strongly ordered models using post-retirement speculation, but these designs either (1) maintain speculative state at a per-store granularity, causing storage requirements to grow proportionally to speculation depth, or (2) employ distributed global commit arbitration using unconventional chunk-based invalidation mechanisms. In this paper we propose InvisiFence, an approach for implementing memory ordering based on post-retirement speculation that avoids these concerns. InvisiFence leverages minimalistic mechanisms for post-retirement speculation proposed in other contexts to (1) track speculative state efficiently at block-granularity with dedicated storage requirements independent of speculation depth, (2) provide fast commit by avoiding explicit commit arbitration, and (3) operate under a conventional invalidation-based cache coherence protocol. InvisiFence supports both modes of operation found in prior work: speculating only when necessary to minimize the risk of rollback-inducing violations or speculating continuously to decouple consistency enforcement from the processor core. Overall, InvisiFence requires approximately one kilobyte of additional state to transform a conventional multiprocessor into one that provides performance-transparent memory ordering, fences, and atomic operations.

Cache invalidation strategies for internet-based mobile ad hoc networks

Internet-based mobile ad hoc network ( Imanet) is an emerging technique that combines a mobile ad hoc network ( Manet) and the Internet to provide universal information accessibility. Although caching frequently accessed data items in mobile terminals (MTs) improves the communication performance in an Imanet, it brings a critical design issue when data updates. In this paper, we analyze several push and pull-based cache invalidation strategies for Imanets. A global positioning system (GPS) based connectivity estimation (GPSCE) scheme is first proposed to assess the connectivity of an MT for supporting cache invalidation mechanisms. Then, we propose a pull-based approach, called aggregate cache based on demand (ACOD) scheme that uses an efficient search algorithm for finding the queried data items. In addition, we modify two push-based cache invalidation strategies, proposed for cellular networks, to work in Imanets. They are called modified timestamp (MTS) scheme and MTS with updated invalidation report (MTS + UIR) scheme, respectively. We compare the performance of all these schemes as a function of query interval, cache update interval, and cache size through extensive simulation. Simulation results indicate that the ACOD scheme provides high throughput, low query latency, and low communication overhead, and thus, is a viable approach for implementation in Imanets.

The Effect of Vacuum Thermal Cycling on LF6 Aluminium Alloy Welded Joints

The investigation aimed at the invalidation mechanism analysis and reliability evaluation of aluminum alloy welded joint under space environment will provide spaceflight designing epartments and manufactures with important technology gist and data so as to greatly reduce paceflights manufactured cost and improve spaceflight working reliability. In this paper, the tensile properties and microstructures of LF6 aluminum alloy welded joint under vacuum thermal cycling have been studied by means of vacuum thermal cycling system. The influence of vacuum thermal cycling on the tensile properties of the welded joint has investigated. Results show that the strength and the enlongation reach their maximum values at about 75 times cycling. The changes of the tensile properties are regarded as resulted from the changes of grain and the motion of dislocation.

Runtime specialization with optimistic heap analysis

We describe a highly practical program specializer for Java programs. The specializer is powerful, because it specializes optimistically, using (potentially transient) constants in the heap; it is precise, because it specializes using data structures that are only partially invariant; it is deployable, because it is hidden in a JIT compiler and does not require any user annotations or offline preprocessing; it is simple, because it uses existing JIT compiler ingredients; and it is fast, because it specializes programs in under 1s.These properties are the result of (1) a new algorithm for selecting specializable code fragments, based on a notion of influence; (2) a precise store profile for identifying constant heap locations; and (3) an efficient invalidation mechanism for monitoring optimistic assumptions about heap constants. Our implementation of the specializer in the Jikes RVM has low overhead, selects specialization points that would be chosen manually, and produces speedups ranging from a factor of 1.2 to 6.4, comparable with annotation-guided specializers.

Invalidation manner and mechanism of new type NbO electrolytic capacitor anode

Niobium suboxide powder was pressed and sintered in vacuum into NbO electrolytic capacitor sintered anode. High voltage and constant current formation experiment was performed on NbO electrolytic capacitor anode, during which electrolyte was 0.01% H3PO4 solution, temperature was 90 °C and current was 50 mA per gram sample. Through the relationship between anode voltage and time and scanning electron microscopy(SEM) images of invalidated anode and normal forming anode, invalidation manner and mechanism of NbO electrolytic capacitor anode were discussed. The results show that, the main invalidation manner of NbO electrolytic capacitor anode is not short circuit but open circuit, which is different to that of traditional Ta electrolytic capacitor anode. The reason of invalidation is that anode oxide film whose thickness increases gradually penetrates the “connection neck’ among anode powder particles, which leads to the open circuit invalidation of anode. Compared with Ta electrolytic capacitor, NbO electrolytic capacitor has better security.