Single Aggregate Research Articles

Effects of design parameters and moisture conditions on interface bond strength between thin friction course (TFC) and underlying asphalt pavements

As a new pavement surface treatment, thin friction course (TFC) is mixed with asphalt emulsion, SBR modifier, single particle size basalt aggregate, and cement. In this study, a test apparatus derived from the pure direct shear test was proposed to investigate the effects of design parameters and moisture conditions on the interface strength. Specifically, the design parameters include the tack coat application rates, the material compositions of TFC, and the texture depths of the underlying pavement. Finally, the analysis of variance (ANOVA) was conducted. According to the results, the increased application rate of tack coat and texture depth of underlying pavement could improve the interface bonding performance. The existence of moisture degraded the bond strength between TFC and the underlying pavement. The increased tack coat application rate could mitigate the detrimental effects of moisture conditions on the interface bond strength. In addition, the optimized material compositions of TFC can only strengthen the interface bond strength slightly. To sum up, the tack coat application rate shows the most significant effect on the interface bond strength, followed by the texture depths of the underlying pavement surface and moisture conditions. Furthermore, the interaction of texture depth and tack coat application rate also has a significant influence on interface bonding performance between TFC and the underlying pavement surface.

Industry 4.0 and Social Development in the Aspect of Sustainable Development: Relations in EC Countries

Purpose: The aim of this paper is to focus on the analysis and assessment of the level of development of Industry 4.0, the social development in the context of the implementation of the concept of sustainable development and to determine the relationship of these phenomena in EU countries. Design/Methodology/Approach: Due to the fact that both Industry 4.0 and social development are complex issues, the research uses taxonomic measures based on the TOPSIS method, which replace the multi-feature description of the studied objects by a single aggregate size, which greatly facilitates their analysis. For the purposes of this article, an attempt was made to construct a synthetic measure of the development of Industry 4.0, as well as a synthetic measure of social development in the context of implementing the concept of sustainable development based on a previously selected set of diagnostic variables. The research also used the so-called threshold method to classify EU countries into homogeneous typological groups. In addition, a correlation analysis was carried out in order to examine whether there is a correlation between the analysed phenomena. Findings: The results of the research indicate that there is a moderate variation in the level of social development in the EU countries in the context of implementing the concept of sustainable development and a significant variation in the level of development of Industry 4.0. The analysis showed that there is a very high positive correlation between the two. Practical Implications: Modern economies are faced with the need to meet the challenges resulting from the fourth industrial revolution, for which the emergence of Industry 4.0 is significant. The changes resulting from the implementation of the concept of Industry 4.0 concern not only industry and its enterprises, but also affect the overall shape of socio-economic processes. Originality/value: Social development considered in connection with the development of Industry 4.0 a relatively new economic category, still not well described in the literature. The way they are combined in the article is a relatively new proposal, important from the point of view of each of these areas.

AGGREGATION OF MS-MONOPYRIDYL-Β-OCTAALKYLPORPHYRINS IN DICHLOROMETHANE IN PRESENCE OF Pd(II)

Aggregation of 13,17-diethyl-2,3,7,8,12,18-hexamethyl-5-(pyridin-4-yl) porphyrin (I), 13,17-diethyl-2,3,7,8,12,18-hexamethyl-5-(pyridin-3-yl)porphyrin (II) and 13.17-diethyl-2,3,7,8,12,18-hexamethyl-5-(pyridin-2-yl)porphyrin (III) in the presence of trans-bis(benzonitrile)palladium(II) dichloride was studied by dynamic light scattering and electronic absorption spectroscopy in dichloromethane at 293 K. The average aggregate size and the nature of their distribution were determined. Using scanning electron microscopy, it was determined the size and composition of clusters formed by aggregates of complexes of the palladium(II) cation with the studied porphyrins. It was shown that minimal acetic acid additions lead to the destruction of the corresponding clusters. At the same time, complete destruction of the aggregates does not occur even with a 100-fold molar excess of acid.We used the Zetasizer Nano ZS (model ZEN3600, Malvern Instruments), equipped with a 633nm laser and non-invasive backscattering (NIBS) technology when the scattered light detector is positioned at an angle of 173° to the incident light. Confirmation of porphyrin aggregation was performed by additional study of the structure using a Hitachi TM4000Plus desktop electron microscope equipped with a 4-segment highly sensitive semiconductor detector and a secondary electron detector for low vacuum mode. Elemental analysis of the obtained aggregates in the cluster was performed using a silicon drift detector with a working area of 30 mm2, combined with a Hitachi TM4000Plus microscope. It was found that aggregates consisting of a para-pyridyl derivative of alkylporphyrin and trans-bis (benzonitrile) palladium (II) dichloride are formed in dichloromethane at 293 K. The best results of porphyrin structures were observed for mixtures of 13,17-diethyl-2,3,7,8,12,18-5-hexamethyl-5-(pyridine-4-yl)porphyrin with TRANS-bis(benzonitrile)- palladium (II) dichloride in a ratio of 1:3, which is probably due to less spatial shielding of the reaction center of the macrocycle and, as a result, better stabilization of the resulting particles. The size of a cluster consisting of individual aggregates was measured using scanning electron microscopy. An elemental analysis of a single aggregate was obtained.

Visualizing NMR‐shielding effect in fullerene‐ZnPc aggregates: Characteristic patterns of ZnP‐based hosts and encapsulation nature from DFT calculations

AbstractThe formation of supramolecular aggregates incorporating C60 fullerenes can be followed and characterized by nuclear magnetic resonance (NMR) measurements. Here, we unravel the particular patterns provided by zinc‐porphyrin (ZnP)‐bridged dimers, where the aromatic character of each ZnP unit leads to an enhanced shielding region for the closest fullerene atoms, denoting a slight shielding effect for the equatorial atoms. The nature of the stabilization is discussed and compared to a single ZnPC60 aggregate and a ZnP‐dimer (ZnP2C60) model, with a significant contribution from noncovalent ππ interactions, allowing us to address the role of bridging chains. The experimental 13C‐NMR spectrum of C60 in a bridged ZnP dimer shows a single peak owing to the constant tumbling inside the host, which averages the different groups of carbon atoms. The calculations in a static scenario reveal information concerning the local chemical environment underlying the observed shift in relation to isolated C60. We expect that the current approach can be useful to rationalize and predict the origin of the NMR shift upon the formation of host‐guest aggregates involving small and large host species.

Construction of an all-organic Z-scheme heterostructure based on 2D PDINH aggregates modified TCPP aggregates by co-assembly with enhanced photocatalytic performance

Supramolecular structures based on orderly aggregated metal-free porphyrins (TCPP) are visible-light-driven photocatalysts. But these photocatalysts possess disadvantages of poor activity and low recycling which limit their practical applications. To improve the activity and deficiencies of TCPP aggregates as photocatalysts, TCPP was combined with organic semiconductor perylene-3,4,9,10-tetracarboxylic diimide (PDINH) aggregates to construct pure organic heterojunctions (TCPP/PDINH) through the co-assembly method in this paper. Through several characterizations, it was concluded that a close contact interface formed through intermolecular π-π stacking and hydrogen bond interactions by the co-assembly method. The photocatalytic activity for the degradation of phenol by TCPP/PDINH was enhanced compared with that of the single aggregate, and the mechanism analysis showed that the matched energy band positions of the two aggregates and the close contact interfaces promoted the formation of a Z-scheme structure, which accelerated the charge carrier separation efficiency. In addition, the existence of two-dimensional PDINH aggregates as a support basement also improved the stability of TCPP aggregates and made them heterogeneous, which enhanced their operation and recycling.

Temperature imaging of mobile BaMgAl10O17:Eu phosphor aggregates under high radiation flux

Planar laser-induced phosphorescence (PLIP) has been used for the temperature measurement of suspended phosphor aggregates. Two-dimensional surface temperature of fluidized phosphor aggregates was measured through a pair of spatial and wavelength resolved images in an environment where phosphors are heated by high-flux radiation. The heating was supplied by a multi-diode laser system which provides a well-characterized high-flux radiation up to 28.87 MW/m2. Phosphors made of BaMgAl10O17:Eu (BAM) were selected as the material and suspended in a fluidized bed. Single-shot temperature imaging of BAM aggregates were inferred and compared at several heat fluxes. With the increasing heat flux up to 28.87 MW/m2, the BAM aggregates were found to exhibit a wider range of temperature distribution, and the maximum average aggregate temperature achieved 723 K, while the maximum temperature of a single aggregate could reach up to 1063 K. The wider temperature distributions that observed under higher radiation fluxes were caused by the elevated temperature of cooling air and the non-uniform aggregate surfaces. This non-intrusive method of measuring temperature offers advantages over other available methods in the study of heat transfer processes involving high-temperature reactions.

Pareto domain: an invaluable source of process information.

Due to the highly competitive market and increasingly stringent environmental regulations, it is paramount to operate chemical processes at their optimal point. In a typical process, there are usually many process variables (decision variables) that need to be selected in order to achieve a set of optimal objectives for which the process will be considered to operate optimally. Because some of the objectives are often contradictory, Multi-objective optimization (MOO) can be used to find a suitable trade-off among all objectives that will satisfy the decision maker. The first step is to circumscribe a well-defined Pareto domain, corresponding to the portion of the solution domain comprised of a large number of non-dominated solutions. The second step is to rank all Pareto-optimal solutions based on some preferences of an expert of the process, this step being performed using visualization tools and/or a ranking algorithm. The last step is to implement the best solution to operate the process optimally. In this paper, after reviewing the main methods to solve MOO problems and to select the best Pareto-optimal solution, four simple MOO problems will be solved to clearly demonstrate the wealth of information on a given process that can be obtained from the MOO instead of a single aggregate objective. The four optimization case studies are the design of a PI controller, an SO2 to SO3 reactor, a distillation column and an acrolein reactor. Results of these optimization case studies show the benefit of generating and using the Pareto domain to gain a deeper understanding of the underlying relationships between the various process variables and performance objectives.

Influence of aggregate interference on the crack propagation of asphalt concrete by the configurational force fracture criterion

In this study, the influence of aggregate interference on the crack propagation of asphalt concrete by the configurational force fracture criterion has been investigated. Since the presence of aggregates inside the asphalt concrete generally changes the nearby stress distribution and exerts a significant impact on the behavior of composite crack growth, the crack passing through single aggregate and asymmetric double aggregate are simulated based on the configurational force fracture criterion using the extended finite element method (XFEM). It was observed that under pure tensile load, the crack will propagate away from the aggregate; but when the crack has an initial deflection angle β, the crack will propagate towards the aggregate, until the crack “pierces” the second aggregate. In terms of the crack tip configurational force, the aggregate has an interference effect on the crack propagation, where the crack tip configurational force decreases with an increase in the aggregate particle size. Moreover, the interference of aggregate on the crack propagation path has a certain limit. It was also found that under the interference of asymmetric double-aggregate; larger the particle size range of the aggregate, easier is the formation of overhead structure inside the material, which eventually results in local instability. This instability drastically affects the crack resistance of the asphalt mixture.

Optimising the response to acute clinical deterioration: the role of observation and response charts.

We sought the role of the hospital inpatient observation and response chart (ORC) in reducing adverse outcomes. We sourced articles written in English and published in PubMed. Track, trigger and response systems can be tiered and use single parameter or aggregate scoring systems; the latter being more prone to error. The documentation and detection of abnormal vital signs can be affected by choice of trigger and response and by ORC design. There is considerable variation in the design of ORC and of rapid response systems (RRS) in general, and this impairs assessment of their efficacy. A high rate of modification of pre-determined triggers and poor sensitivity of measured outcomes further compromise systematic review. The best-designed ORC and RRS should optimise the frequency of response team activation to minimise adverse patient outcomes without excess resource utilisation. The role and the risks of electronic data recording are under-explored. Detecting and responding to deteriorating patients relies upon accurate and clear documentation of vital signs. ORC design and staff education on ORC implementation and usage are integral to minimising ALF and optimising patient outcomes. Standardisation of the design of both the ORC and the hospital RRS are overdue.

Three-dimensional ordered Ag/ZnO/Si hierarchical nanoflower arrays for spatially uniform and ultrasensitive SERS detection

Surface-enhanced Raman scattering (SERS) is a powerful analytic tool that can provide information of molecular structures and composition of analytes. The application of SERS for ultrasensitive detection of chemical and biological molecules has attracted particular interests in recent years. Here, a novel type of three-dimensional SERS substrate with uniform hierarchical nanoflower structures was fabricated by growing dense ZnO nanowires (ZnO NWs) on ordered vertically aligned Si nanorods (Si NRs) through a chemical hydrothermal (HT) method. After being decorated with Ag nanoparticles (Ag NPs), such branched nanostructure exhibits greatly improved SERS signals with a detection limit of Rhodamine 6 G (R6 G) down to 1 pM and an excellent uniformity (relative standard deviation lowered to about 6%). Furthermore, this SERS-active substrate is successfully applied to investigate the aggregation status of human islet amyloid polypeptides (hIAPP). The structural change of amyloid aggregates can be detected from SERS spectra at a single aggregate level, providing useful information for the prevention and treatment of protein conformation diseases. Therefore, our studies not only demonstrate a promising type of SERS substrates for highly uniform, reproducible and ultrasensitive molecular detection, but also suggest a potential method for label-free detection on conformation change of amyloid peptides in aggregation process.

Impact of origination of expansion on three-dimensional expansion crack propagation process due to DEF evaluated by mesoscale discrete model

In this study, DEF expansion crack propagation process under different restraint condition was numerically investigated by mesoscale discrete model, which describes concrete material with coarse aggregate phase and mortar phase using 3D-Rigid Body Spring Model. The purpose of this study is to clarify the impacts of origination of expansion and aggregate on characteristic DEF expansion such as localized expansion crack and cracks localized at the ITZ between paste and aggregate. In this analysis, Single Aggregate Model and Multi-Aggregate Model were constructed to verify expansion crack propagation process and interaction between aggregate and mortar phases precisely. As a result of Single Aggregate model, it was confirmed that expansion crack tends to be localized as expansion phase ratio is lower, and cracks localized at the ITZ is appeared at the early stage of expansion. By using Multi-Aggregate Model, the analytical results of expansion crack propagation process, stress distribution change, and expansion strain change under different restraint condition were coincided with experimental observation. In addition, it was found that origination of expansion strongly influences to DEF expansion. In terms of aggregate, the existence of aggregate and grain size distribution slightly inhibit expansion strain development and crack volume development, and their impacts on DEF expansion, however, seems to be small. This is because cracks localized at the ITZ generates at the early stage of expansion process and the stress transfer mechanism between mortar and aggregate phase disappears.

Quantized Grain Boundary States Promote Nanoparticle Alignment During Imperfect Oriented Attachment.

Oriented attachment (OA) has become a well-recognized mechanism for the growth of metal, ceramic, and biomineral crystals. While many computational and experimental studies of OA have shown that particles can attach with some misorientation then rotate to remove adjoining grain boundaries, the underlying atomistic pathways for this "imperfect OA" process remain the subject of debate. In this study, molecular dynamics and in situ transmission electron microscopy (TEM) are used to probe the crystallographic evolution of up to 30 gold nanoparticles during aggregation. It is found that Imperfect OA occurs because 1) grain boundaries become quantized when their size is comparable to the separation between constituent dislocations and 2) kinetic barriers associated with the glide of grain boundary dislocations are small. In support of these findings, TEM experiments show the formation of a single crystal aggregate after annealing nine initially misoriented, agglomerated particles with evidence of dislocation activity and twin formation during particle/grain alignment. These observations motivate future work on assembled nanocrystals with tailored defects and call for a revision of Read-Shockley models for grain boundary energies in nanocrystalline materials.

Interaction of doxorubicin hydrochloride in the presence of, mixed aggregate of ibuprofen sodium and cationic lipid

This research was highlighted the importance of mixed aggregates based on drug-lipid to improve the interaction of one or more drugs in aqueous medium. This mixed aggregate can significantly inhibit the growth of MCF-7 cells, and has great potential for anti-inflammatory and cancer treatment after tumor removal. The cationic lipid (CL) has been synthesized with multistep reaction and is characterized by 1H NMR and mass spectroscopy. CL and ibuprofen (IBF) physiochemical analysis was investigated using surface tension, conductance, dynamic light scattering (DLS), and electron microscope transmission (TEM). The strong synergism between mixed aggregate (LIB) system CL and IBF was observed. The study on UV spectroscopy measured that the LIB mixed aggregate showed optimum binding to doxorubicin hydrochloride (DOX) and the binding constant Log Kb was 6.17 compared to single CL, the Log Kb was 5.83. Binding results indicated that the DOX was more encapsulated in mixed LIB aggregates compared to single CL aggregates. This mixed aggregate LIB has excellent performance in controlling the release of drugs. For single CL aggregate, approximately 62.5% DOX was released after 72 h (pH = 7.4). However, LIB such as, (0.1αCL+ 0.9αIBF), the release of DOX decreased to 16.08%. Finally, LIB mixed aggregate applicability has been used to minimize the cytotoxicity of MCF-7 cells, and it has been found that DOX in LIB mixed aggregates has a higher inhibitory effect on cell growth than DOX in CL.

Regional Differentiation for Life Quality of the Population in Ukraine Under Innovative Growth

Abstract The article focuses on the analysis of economic growth of Ukraine and its regions, using the proposed by the authors indicators of quality and indicators of the population living standards under innovation growth. The main purpose of the research is developing a method of multi-factor assessment and regional classification of population`s life quality. Moving to the results literature review showed that many approaches to assessing the quality of life of the population have been developed in the statistical theory and practice. However, still, there are many discussions about the question of a single aggregate indicator of living standards and the methodology of regional differentiation by this criterion. So, it has not been found a rational way to combine indicators of the level and quality of life to obtain a comprehensive index that reflects objectively, reliably and verifiable the population`s level and quality of life. The main discovered disadvantage of existing methods is the use of the expert estimation method, which does not allow guaranteeing validity the weight of the criteria for estimation the quality of life indicator. Nevertheless, all authors admitted that today the role of the state rises in solving the most important social and economic problems, therefore, the task to increase the efficiency of the regions` functioning based on innovation activity becomes of key importance. The analysis of regional activity`s effectiveness considering the innovation component is the most important part of national administration. In the article the research of the question of multi-factor assessment and regional classification the quality of the country population`s life is carried out in the following logical sequence: theoretical analysis of categories of living standards and quality of life; development of the statistical indicators system at the regional level for assessing the quality of life of the population; distribution of the entire system of indicators for certain economic categories; receiving indexes for each region by each category; realization of regional clustering with the received system of indexes. The methodical tools of the research were general scientific methods: analysis (conducted analysis of definitions for concepts of the standard of living and quality of life); synthesis (combination of separate research methods into a unified methodology of regional differentiation by the quality of life); deduction (initially it is analyzed all the proposed systems of indicators in general, and then they are divided into economic categories); abstraction (separation of a significant indicators system for the implementation of regional differentiation in terms of innovation development of the living standard of the population from the entire statistical information), specification (revealing specific characteristics of the received categories and clusters); comparison (comparison of regions according to the indicators of the population`s life quality level), classification (grouping of individual indicators into economic categories); generalization (with the help of which conclusions were drawn). There were also used some special methods: cluster methods (the tree clustering method and k-means clustering of the regions of Ukraine by the basic indicators of population`s living standards), the method of the main components (for the development of regional indexes for each category). The research was carried out for the data of 2017 year as the last year, for which statistical information is available with most indicators in a regional context. The object of the study is Ukraine and its 24 regions. The city of Kyiv was highlighted as the capital. The article presents the results of the empirical analysis of the level and quality of population`s life indicators, which allowed to allocate five clusters and a set of indicators for regional differentiation. The study empirically confirms the presence of regional clusters in the category of living standards and theoretically proposes a methodology for its implementation in conditions of innovative development. The results of the study can be useful for analyzing various scenarios for the implementation of social policy aimed at financial and economic protection of the population ensuring. It was shown that for certain regions the quality of population`s life should be considered as a task of their innovative growth.

Compaction Dynamics during Progenitor Cell Self-Assembly Reveal Granular Mechanics

Summary We study the self-assembly dynamics of human progenitor cells in agarose microwells that are used for production of chondrogenic organoids. Using image analysis on time-lapse microscopy, we estimate the aggregate area in function of time for a large number of aggregates. In control conditions, the aggregate radius follows an exponential relaxation that is consistent with the dewetting dynamics of a liquid film. Upon introducing Y-27632 Rho kinase inhibitor, the compatibility with the liquid model is lost, and slowed-down relaxation dynamics are observed. We demonstrate that these aggregates behave as granular piles undergoing compaction, with density relaxation that follows a stretched exponential. Using simulations with an individual cell-based model, we construct a phase diagram of cell aggregates that suggests that the aggregate in presence of Rho kinase inhibitor approaches glass transition.

Spatiotemporal Dynamics of Aggregation-Induced Emission Enhancement Controlled by Optical Manipulation.

We present spatiotemporal control of aggregation-induced emission enhancement (AIEE) of a protonated tetraphenylethene derivative by optical manipulation. A single submicrometer-sized aggregate is initially confined by laser irradiation when its fluorescence is hardly detectable. The continuous irradiation of the formed aggregate leads to sudden and rapid growth, resulting in bright yellow fluorescence emission. The fluorescence intensity at the peak wavelength of 540 nm is tremendously enhanced with growth, meaning that AIEE is activated by optical manipulation. Amazingly, the switching on/off of the activation of AIEE is arbitrarily controlled by alternating the laser power. This result means that optical manipulation increases the local concentration, which overcomes the electrostatic repulsion between the protonated molecules, namely, optical manipulation changes the aggregate structure. The dynamics and mechanism in AIEE controlled by optical manipulation will be discussed from the viewpoint of molecular conformation and association depending on the laser power.

Evaluating Angularity of Coarse Aggregates Using the Virtual Cutting Method Based on 3D Point Cloud Images

In this paper, a new method called the Virtual Cutting Method is proposed to evaluate the angularity index (AI) values of 3D point cloud coarse aggregate images with the aim of characterizing the angularity of aggregates on conveyor belts. The 3D point cloud images of coarse aggregates were first captured, preprocessed, and segmented into single 3D aggregate objects. Based on the processed 3D aggregate images, intersection contours were extracted using a series of intersection planes with an equivalent angle between two adjacent planes. The AI was evaluated by averaging the angularity of the contours using the gradient method, which was used in the AIMS2 system. Statistical analysis was then performed to select the optimum angle between two adjacent planes. It was found that an angle of five degrees was the ideal angle, as it can balance the execution time and effectiveness of the method. Finally, the AI results of the Virtual Cutting Method were compared with those of 2D and 3D Projection Methods. It was found that the AI rankings of the three methods for different aggregate textures are generally consistent. The findings of this study conclude that the Virtual Cutting Method can be employed to quantify the angularity of a single aggregate or aggregates in piles on conveyor belts based on 3D point cloud images.

Теоретические аспекты правовой природы коллективного субъекта права

Theoretical aspects of the legal nature of the collective subject of law The article reveals the category of “collective subject” in law. It is based on the principle of a collective nature and its theoretical basis. The author conducts a comparative analysis of existing approaches to the consideration of the collective subject of law. Moreover, the embodiment of a collective subject is precisely a corporation that unites individuals into a single aggregate. Its legal capacity includes three components: corporate power, public rights and legal relations with other persons.

From Load to Net Energy Forecasting: Short-Term Residential Forecasting for the Blend of Load and PV Behind the Meter

As distribution networks worldwide are experiencing the adoption of residential solar photovoltaic (PV) more than ever, the need for transiting from the concept of load forecasting to net energy forecasting, i.e. predicting the blend of PV and load as a whole, is pressing. While most of the existing literature has focused on load forecasting, this paper, for the first time, contributes to this transition at both single household and low aggregate levels through a comprehensive study. The paper also proposes a multi-input single-output (MISO) model based on an efficient long short-term memory (LSTM) neural network, by which different household energy profiles help provide more accurate forecasts for other households or aggregate energy profile. This technique, indeed, considers the spatial dependencies of households’ profile indirectly. Through this study, the underlying problem of short-term net energy forecasting is compared to load forecasting, and it is shown how the inclusion of PV generation behind the meter could deteriorate forecasting accuracy. Moreover, the impact of the level of granularity associated with smart meter data on the aggregated net energy forecasting is discussed, and it is revealed that the higher resolution data can potentially alleviate the accuracy lost. Furthermore, online LSTM, as opposed to proposed batch learning MISO LSTM, is used as a forecasting tool. The results show online LSTM is more resilient to sudden changes at the single household level, while MISO LSTM is efficient for aggregate level. The proposed framework is conducted on two real Ausgrid and Solar Analytics case studies in Australia.

Learning Recurrent 3D Attention for Video-Based Person Re-Identification

In this paper, we propose to learn recurrent 3D attention (A3D) for video-based person re-identification. Attention model plays a key role in both spatial and temporal domains for video representation. Most existing methods apply spatial attention model to extract feature from a single image and aggregate image features with attentive temporal pooling or RNN. However, the inherent consistencies and correlations between spatial and temporal clues are not leveraged. Our A3D method aims to utilize the joint constraints of temporal and spatial attentions to enhance the robustness of attention model. Towards this goal, we treat the pedestrian video as a unified 3D bin where the temporal domain is denoted as an additional dimension. Then we develop an attention agent to iteratively select the locations of the salient spatial-temporal parts in the 3D bin. In addition, we formulate our sequential 3D attention learning as a Markov Decision Process and train the representation network and attention detector with the policy gradient method in an end-to-end manner. We evaluate the proposed method on three challenging datasets including iLIDS-VID, PRID-2011 and the large-scale MARS dataset, and consistently improve the performance in comparison with the state-of-the-art methods.