Congested Spaces Research Articles

Improving IMU-Based Prediction of Lower Limb Kinematics in Natural Environments Using Egocentric Optical Flow.

We seek to predict knee and ankle motion using wearable sensors. These predictions could serve as target trajectories for a lower limb prosthesis. In this manuscript, we investigate the use of egocentric vision for improving performance over kinematic wearable motion capture. We present an out-of-the-lab dataset of 23 healthy subjects navigating public classrooms, a large atrium, and stairs for a total of almost 12 hours of recording. The prediction task is difficult because the movements include avoiding obstacles, other people, idiosyncratic movements such as traversing doors, and individual choices in selecting the future path. We demonstrate that using vision improves the quality of the predicted knee and ankle trajectories, especially in congested spaces and when the visual environment provides information that does not appear simply in the movements of the body. Overall, including vision results in 7.9% and 7.0% improvement in root mean squared error of knee and ankle angle predictions respectively. The improvement in Pearson Correlation Coefficient for knee and ankle predictions is 1.5% and 12.3% respectively. We discuss particular moments where vision greatly improved, or failed to improve, the prediction performance. We also find that the benefits of vision can be enhanced with more data. Lastly, we discuss challenges of continuous estimation of gait in natural, out-of-the-lab datasets.

An experimental study on self compacting geo-polymer concrete containing Metakaolin at ambient curing condition

The production of cement consumes considerable energy and releases a huge amount of CO2 which is not eco-friendly. One of the possible alternatives is to use alkaline activated binders with the by-products obtained from industries such as fly ash and Ground Granulated Blast Furnace Slag which includes the silicate materials. Accordingly, the worlds suggested innovative concrete; Geopolymer Concrete exhibits mechanical and durability properties against the OPC. Special concretes should possess the ability to flow, pass through small spaces and should be able to fill the narrow gaps of the congested spaces in the structural elements. Self Compacted Concrete is one such special concrete, originally developed in Japan which can handle the workability and durability issues without sacrificing the strength. In the following study, detail investigation of experimental studies is carried out to derive Self Compacting Geopolymer Concrete (SCGPC) with powder content of Fly ash, GGBS and Metakaolin (MK). Superplasticizer is used to improve the workability. Different percentages of GGBS and MK are individually and combinedly added to the constant amount of Fly ash to study the varying results. The Fresh property of concrete are analysed by conducting Slump flow, V Funnel T50 sec, L- box test procedures. Hardened properties are derived by tensile, flexural and compressive strength tests. The study resulted that after the addition of Superplasticizer and presence of Mk shows good workability and the hardened properties improved with increase in percentages of MK and GGBS.

Chemical complexity of the retina addressed by novel phasor analysis of unstained multimodal microscopy

Abstract Unstained multimodal microscopy is capable of non-invasively obtaining chemically specific information with sub-micron spatial resolution; however, spectral overlap makes quantitative analysis difficult. Here, multimodal images that include second-harmonic generation, third-harmonic generation, and two- and three-photon excited fluorescence signals from unstained retinas are analyzed. The composition from each layer of the retina is determined using a novel variation of phasor analysis that is not limited to three components. The super-phasor unmixing (SPU) method is compared with fully constrained linear spectral unmixing. The seven spectroscopic signals in the spectral range 300–690 nm enable the quantitative unmixing of sub-micron pixel spectra even in the presence of noise. The performance of SPU was found to be significantly superior to linear unmixing especially in regions of high spectral overlap. The analysis being presented represents an important step in addressing chemical complexity in congested spaces with applicability to biomedical imaging and unmixing of hyperspectral images.

3D Printed Biomimetic Soft Robot with Multimodal Locomotion and Multifunctionality.

Soft robots can outperform traditional rigid robots in terms of structural compliance, enhanced safety, and efficient locomotion. However, it is still a grand challenge to design and efficiently manufacture soft robots with multimodal locomotion capability together with multifunctionality for navigating in dynamic environments and meanwhile performing diverse tasks in real-life applications. This study presents a 3D-printed soft robot, which has spatially varied material compositions (0-50% particle-polymer weight ratio), multiscale hierarchical surface structures (10 nm, 1 μm, and 70 μm features on 5 mm wide robot footpads), and consists of functional components for multifunctionality. A novel additive manufacturing process, magnetic-field-assisted projection stereolithography (M-SL), is innovated to fabricate the proposed robot with prescribed material heterogeneity and structural hierarchy, and hence locally engineered flexibility and preprogrammed functionality. The robot incorporates untethered magnetic actuation with superior multimodal locomotion capabilities for completing tasks in harsh environments, including effective load carrying (up to ∼30 times of its own weight) and obstacle removing (up to 6.5 times of its own weight) in congested spaces (e.g., 5 mm diameter glass tube, gastric folds of a pig stomach) by gripping or pushing objects (e.g., 0.3-8 times of its own weight with a velocity up to 31 mm/s). Furthermore, the robot footpads are covered by multiscale hierarchical spike structures with features spanning from nanometers (e.g., 10 nm) to millimeters. Such high structural hierarchy enables multiple superior functions, including changing a naturally hydrophilic surface to hydrophobic, hairy adhesion, and excellent cell attaching and growth properties. It is found that the hairy adhesion and the engineered hydrophobicity of the robot footpad enable robust navigation in wet and slippery environments. The multimaterial multiscale robot design and the direct digital manufacturing method enable complex and versatile robot behaviors in sophisticated environments, facilitating a wide spectrum of real-life applications.

Mask wearing in pre-symptomatic patients prevents SARS-CoV-2 transmission: An epidemiological analysis

ObjectivesPandemic COVID-19 has become a seriously public health priority worldwide. Comprehensive strategies including travel restrictions and mask-wearing have been implemented to mitigate the virus circulation. However, detail information on community transmission is unavailable yet. MethodsFrom January 23 to March 1, 2020, 127 patients (median age: 46 years; range: 11–80) with 71 male and 56 female, were confirmed to be infected with the SARS-CoV-2 in Taizhou, Zhejiang, China. Epidemiological trajectory and clinical features of these COVID-19 cases were retrospectively retrieved from electronic medical records and valid individual questionnaire. ResultsThe disease onset was between January 9 to February 14, 2020. Among them, 64 patients are local residents, and 63 patients were back home from Wuhan from January 10 to 24, 2020 before travel restriction. 197 local residents had definite close-contact with 41 pre-symptomatic patients back from Wuhan. 123 and 74 of them contact with mask-wearing or with no mask-wearing pre-symptomatic patients back from Wuhan, respectively. Data showed that incidence of COVID-19 was significantly higher for local residents close-contact with no mask-wearing Wuhan returned pre-symptomatic patients (19.0% vs. 8.1%, p < 0.001). Among 57 close-contact individuals, 21 sequential local COVID-19 patients originated from a pre-symptomatic Wuhan returned couple, indicated dense gathering in congested spaces is a high risk for SARS-CoV-2 transmission. ConclusionsOur findings provided valuable details of pre-symptomatic patient mask-wearing and restriction of mass gathering in congested spaces particularly, are important interventions to mitigate the SARS-CoV-2 transmission.

Probation staff supervision: Valuing ‘me time’ within congested spaces

Probation staff supervision is an established professional practice tool, documented historically through the lens of the Probation Journal. This article charts Journal discussions surrounding staff supervision and places them alongside a recent research study examining current practice. Study findings indicate that staff value dedicated time and space for structured supervision that contains significant elements of a more clinical approach. Nevertheless, supervision functions within congested spaces in which managerial aspects of staff engagement encroach. Finding an accommodation between differing approaches appears challenging. More broadly, competing views resound within a landscape of looming professional registration and associated requirements of continuous professional development.

A Magnetorheological Fluid-Filled Soft Crawling Robot With Magnetic Actuation

While soft/partially soft-bodied robots have extensive applications, robust actuation system, efficient locomotion gait, and simple manufacture process are the main challenging problems. To address these challenges, this article proposes a novel magnetorheological fluid (MRF)-filled soft crawling robot with magnetic actuation in congested spaces as a transport function. In this new soft robot, MRF is innovatively applied to establishing a robust actuation system owing to its characteristics of millisecond magnetization, zero magnetic coercivity, and flexible integration. Because the crawling locomotion of the robot is generated by the anisotropic magnetic torque, when the magnetic field is closed neither components of the proposed robot will magnetically interfere with each other. Thus, an efficient locomotion gait can be realized. Lastly, 3-D printing 3-DP has been employed to manufacture the soft robot, which will make the manufacture process simple and costless. Both numerical and experimental evaluations were performed to analyze the dynamics of the newly designed MRF crawling robot with single-step and continuous locomotion conditions. The experimental test result was basically consistent with the simulation, which indicates good movement feasibility of the proposed crawling robot.

Center-of-Gravity-Based Approach for Modeling Dynamics of Multisection Continuum Arms

Multisection continuum arms offer complementary characteristics to those of traditional rigid-bodied robots. Inspired by biological appendages, such as elephant trunks and octopus arms, these robots trade rigidity for compliance and accuracy for safety and, therefore, exhibit strong potential for applications in human-occupied spaces. Prior work has demonstrated their superiority in operation in congested spaces and manipulation of irregularly shaped objects. However, they are yet to be widely applied outside laboratory spaces. One key reason is that, due to compliance, they are difficult to control. Sophisticated and numerically efficient dynamic models are a necessity to implement dynamic control. In this paper, we propose a novel numerically stable center-of-gravity-based dynamic model for variable-length multisection continuum arms. The model can accommodate continuum robots having any number of sections with varying physical dimensions. The dynamic algorithm is of $\mathcal {O}\left(n^{2}\right)$ complexity, runs at 9.5 kHz, simulates six to eight times faster than real time for a three-section continuum robot, and, therefore, is ideally suited for real-time control implementations. The model accuracy is validated numerically against an integral-dynamic model proposed by the authors and experimentally for a three-section pneumatically actuated variable-length multisection continuum arm. This is the first sub-real-time dynamic model based on a smooth continuous deformation model for variable-length multisection continuum arms.

A review on effects of different factors on gas explosions in underground structures

Underground structures are normally located in highly-confined and congested spaces, which may lead to severe gas explosion accidents, with significant human and economic losses. For accurately evaluating the consequences of these explosions, a variety of influencing factors need to be considered, including concentrations of gas mixtures, vent conditions, obstacles, and ignition features. Moreover, a good review on these influencing factors is important for a better understanding of explosion behavior, e.g., the deflagration to detonation phenomenon. In this study, some critical influencing factors for gas explosions in underground or confined spaces are investigated, and the effects of the factors on such gas explosions are examined. The results are discussed, along with findings from literature. The present study provides a reference for future studies on safety management and consequence mitigation for underground gas explosions.

A Fully Three-Dimensional Printed Inchworm-Inspired Soft Robot with Magnetic Actuation.

In the field of robotics, researchers are aiming to develop soft or partially soft bodied robots that utilize the motion and control system of various living organisms in nature. These robots have the potential to be robust and versatile, even safer for human interaction compared to traditional rigid robots. Soft robots based on biomimetic principles are being designed for real life applications by paying attention to different shape, geometry, and actuation systems in these organisms that respond to surrounding environments and stimuli. Especially, caterpillars or inchworms have garnered attention due to their soft compliant structure and crawling locomotion system making them ideal for maneuvering in congested spaces as a transport function. Currently, there are two major challenges with design and fabrication of such soft robots: using an efficient actuation system and developing a simple manufacturing process. Different actuation systems have been explored, which include shape memory alloy based coils and hydraulic and pneumatic actuators. However, the intrinsic limitations due to overall size and control system of these actuators prevent their integration in flexibility, lightweight, and compact manner, limiting practical and untethered applications. In comparison, magnetic actuation demonstrates simple wireless noncontact control. In terms of manufacturing process, additive manufacturing has emerged as an effective tool for obtaining structural complexity with high resolution, accuracy, and desired geometry. This study proposes a fully three-dimensional (3D) printed, monolithic, and tetherless inchworm-inspired soft robot that uses magnetic actuation for linear locomotion and crawling. Its structure is multimaterial heterogeneous particle-polymer composite with locally programmed material compositions. This soft robot is directly printed in one piece from a 3D computer model, without any manual assembly or complex processing steps, and it can be controlled by an external wireless force. This article presents its design and manufacturing with the novel magnetic field assisted projection stereolithography technique. Analytical models and numerical simulations of the crawling locomotion of the soft robot are also presented and compared with the experimental results of the 3D printed prototype. The overall locomotion mechanism of the magnetically actuated soft robot is evaluated with friction tests and stride efficiency analysis.

Environment Friendly Mass Housing for Informal Settlement

Rapid Urbanization, migration of labour forces and acute congested spaces with unhygienic condition are distinct character of all urban settlement. The present paper precisely takes up this issue with an objective to provide better environmental qualities in their living environment. The work addresses to “environment friendly” approach in preparation of the housing project. The hierarchical plan modules are designed in terms of cluster units, cluster blocks and “EF-MH” (Environment Friendly–Mass Housing) Blocks. The planning thrust is on group housing and cluster housing to introduce the sense of social cohesiveness and intimacy among the slum dwellers, through the provision of space at shelter, assembly and cluster unit levels. Open condominium and inter-locking cluster blocks are used to inter link the multilevel open spaces in effective way. Ultimate aim is to make housing schemes interested and of better environmental quality on one hand and socially cohesive, acceptable and appreciable plan for the urban poor on the other.

“Smashing Images in Your Face”: Mobile Perception and Urban Media in James Rosenquist’s Pop

James Rosenquist’s paintings of the early 1960s have been interpreted as a Pop synthesis of media imagery and the formal and aesthetic logic of mid-century American abstract art. These composites of image fragments also confront the mechanisms and operations of the mobilized gaze at a time of intense anxiety over the negative psychological effects of popular visual media. The products, bodies, and vehicles vying for space in his works reference everyday collisions between images generated by consumer culture and the congested urban spaces where they circulated most heavily. Rosenquist’s work is unique within Pop art in its systematic evocation of the sensory experiences of urban vision, characterized by shifts in movement, scale, and time of exposure to produce moments of erratic, distracted looking, as well as a sustained, immersive gaze. By considering the artist’s statements on city life and his career as a Times Square billboard painter, as well as contemporaneous theories and descriptions of modern visuality, this article interprets Rosenquist’s project as primarily an exploration of the destabilizing visual effects of urban life and the modern image. It frames his work as equally relevant to abstraction in the everyday as to modernist aesthetics.

A multivariable approach for estimation of vapor cloud explosion frequencies for independent congested spaces to be used in occupied building risk assessment

API Recommended Practice 752 is one of the most referenced practices for evaluating vapor cloud explosion (VCE) impacts to site occupied buildings. This reference introduces generic VCE frequencies for different types of process units that are based on VCE incidents database. Although these reported VCE frequencies are not capable of illustrating all parameters that affect explosion likelihood, they are widely used in risk analysis studies and software packages. This paper delineates the structure of a more realistic method for estimation of local VCE frequencies for independent congested spaces or units as a function of process, site, and meteorological variables. Compared to traditional methods for VCE frequency estimation, the new proposed approach is supported by an obviously more populated and precisely categorized database of leakage frequencies and features a multi-variable functionality of process/plant conditions. Contrary to previous procedures that aimed at finding the frequency of occurrence for a single VCE incident, this proposed methodology characterizes each congested space with a local VCE frequency. This frequency is an integration of the frequencies pertaining to VCE's that are likely to be initiated by each congested space. This new VCE frequency can also be used to determine the level of explosion hazard in each unit and in risk matrix analysis.

Distribution of small packages in metropolitan area by motorcycle courier services

Small packages such as important documents, receipts and gifts are usually distributed in a short time window in a metropolitan area of congested traffic and limited parking spaces. While conventional four-wheel vehicles are not suitable for intra-city deliveries, motorcycles are perfect since they are more mobile. This paper tries to investigate business models suitable for distributing small packages in metropolitan area by analysing two courier networks: a point-to-point and a hub-and-spoke courier network. Pros and cons, as well as the simplified mathematical models for these two networks will be proposed and analysed to give more insights for this business.

Planning Public Transport Networks for the 2004 Summer Olympics with Decision Support Systems

During the 2004 Summer Olympics, in Athens, Greece, transit passengers will be mainly accommodated by public transportation modes. The large number of passengers expected to be carried, combined with the congested road network and limited parking spaces, will make it difficult for private vehicles to be used during the games; as such, use of mass transportation will be necessary. An extended public transportation network is being planned that consists of three lines of the Athens Metro, a suburban rail line, two tram lines, and 30 dedicated Olympic bus lines in addition to regular bus lines. Planning of the network is a complicated process with more than 30 Olympic bus lines connecting Olympic venues with Athens downtown, other venues, Metro stations, and park-and-ride areas. Metro lines will be operating 24 h/day, many hours near capacity. To assist in this effort, a decision support system was developed to help plan the Olympic public transportation network operations. The user-friendly system is supported by a graphical user interface and based on widely available software packages. Its capabilities include data storage, management, graphical analysis, analysis with the use of specialized algorithms, and extraction of proposed courses of action.

The environmental challenges in Sub-Saharan Africa.

Countries in sub-Saharan Africa are doing some rethinking, after decades of development that have resulted in continued poverty, international indebtedness, environmental degradation, and inappropriate Western models. Technological innovations, institutional developments, and family planning are key inputs. Development should shift to a focus on elimination of widespread poverty. Past development strategies in an African context of ample resources have harmed the environment without improving the average person's standard of living. Knowledge about Africa's environment and environmental degradation is inadequate. Recent studies have found, contrary to popular belief, that small shareholders made considerable investments in resource-based capital, which protected their farms from major environmental deterioration and negative impacts of intensification. In Nigeria field studies found that rising demand for fuelwood did not lead to greater deforestation or desertification. Severe degradation has occurred in places where density of population is greater than 500 persons per sq. km, where the land is physically or biologically vulnerable, and where socioeconomic conditions interfere with application of conservation measures. Reduced well-being and reduced food capacity is attributed to land tenure arrangements, misguided macroeconomic policies, and inadequate infrastructure. The issues of development, environment, and population are complex. Sustainable development is possible with appropriate investment priorities that will provide needed infrastructure, services, and education. Urban areas need safe water, solid waste disposal, and spatial planning to relieve congested spaces. Rural areas should focus on health education and basic sanitation. Regulatory measures and conservation measures are also important. Institutional development that promotes democracy, expands individual property rights, and increases the knowledge base offers the most hope for alleviating poverty and protecting the environment.

An Algorithm for the Generation of an Optimum CMM Inspection Path

An algorithm for generating an optimum CMM inspection path is developed to improve the throughput of CMMs. In this algorithm, a modified 3-D ray tracing technique is applied to an octree database of a CMM configuration space to detect obstacles between any two target points. After an obstacle is detected, collision-free silhouette contour vertices of the object are generated, from a selection criterion, as potential points of a vertex path. As the ray advances, a sequential-decision-making technique is used to derive the suboptimum vertex path from possible collision-free vertex paths. After the suboptimum vertex path is generated, a selection strategy is employed to ensure a correct edge path sequence for deriving an optimum edge point path. A 3-D simulation shows that the proposed global algorithm eliminates the dynamically undesirable characteristics of octree based algorithms and saves searching time in congested work spaces by finding paths around colliding objects. Actual measurement of a test part indicates that the proposed method can reduce the inspection time to less than half as compared to the interactive graphic method.