Architectural Constraints Research Articles

T-REST: An Open-Enabled Architectural Style for the Internet of Things

Computing offloading is a key challenge of new rising computing paradigms of the Internet of Things (IoT) like edge computing, which shifts computations to data sources as near as possible to gain the benefits, such as low latency and energy efficiency. However, the fragmentation problem of IoT devices results in a heterogeneous and disordered ecosystem, hindering the interoperating demands of computing offloading. What we need is an open-enabled ecosystem which allows third-party developers to create and update functions of deployed devices dynamically. We propose Things-representational state transfer (T-REST) which is an extension of the representational state transfer (REST) architectural style to address this problem. It integrates contents and computations together to inherit the uniform interface principle from REST. Three architectural constraints are added to REST: 1) reusable remote evaluation; 2) dynamic time series representation; and 3) computational hypertext. A novel event triggering mechanism is designed to decouple the tight coupling of front-end content accesses and back-end computations for resources. A reference prototype, named T-REST engine, is implemented to verify the proposed architecture with the open-enabled style, distributed semantics, and computing offloading features. Discussions show that T-REST preserves the benefits of REST. In addition, it achieves extremely lightweight footprints and can perform computing offloading through open-enabled architectures.

Greening Actions and the Related Potential Impacts on Outdoor Comfort in a Dense Built Environment

The increasing attention paid to the effects of climate change on the dense urban fabric of contemporary cities had led Public Authorities to develop local adaptation plans in order to suggest some effective measures to mitigate and reduce the impacts of urban heat island [UHI] and heat waves as well as to improve water management capacity. Among the suggested actions, the greening of in-between spaces of the built environment and the introduction of new green surfaces (roof and/or facades) in the framework of wider regeneration plans offers interesting perspectives and impacts. The paper reports the outcomes of a research activity run by the Department of Architecture and the Municipality of Bologna to investigate how to define/optimize the most effective arrangement of greening solutions with the aim to improve outdoor comfort conditions. The study takes into account several aspects including paved/green surfaces extension, the use of material, the geometry of the site, etc. and simulate the potential effects of changes using simulation software ENVIMET. Once the main features of each site are modelled the different deriving scenarios can be compared evaluating the different architectural, economical and practical constraints. The results are then compared with other factors, related to the social aspects, the use of the spaces, the perception of the sites, etc. A district of the city of Bologna is used as test bed in order to test the proposed methodology and the related potential impacts.

Architectural constraints, male fertility variation and biased floral morph ratios in tristylous populations.

Tristyly is a genetic polymorphism in which populations are comprised of three floral morphs (mating types) differing reciprocally in sex-organ height. Intermorph (disassortative) mating governed by a trimorphic incompatibility system should result in 1:1:1 morph ratios at equilibrium, but both deterministic and stochastic processes can cause skewed morph ratios in tristylous populations. Here, we investigate mechanisms causing morph-ratio bias in Pontederia parviflora, an emergent aquatic native to tropical America. We compared reproductive traits among morphs and surveyed 71 populations to determine patterns of morph-ratio bias. We then used simulation models of morph-frequency dynamics to test the hypothesis that morph-specific differences in pollen production and their influence on male fertility can explain patterns of morph-ratio bias. Ninety-seven percent of populations that we sampled were tristylous, but with a significant excess of the short-styled morph and a deficiency of the long-styled morph. Atypically for a tristylous species, mid-level anthers of the short-styled morph produced over twice as much pollen compared with the corresponding anthers of the long-styled morph. Our computer models incorporating this difference in male fertility resulted in morph ratios not significantly different from the average frequencies from our survey suggesting that the short-styled morph is more successful than the long-styled morph in siring ovules of the mid-styled morph. We propose that the difference in male fertility between morphs may be a non-adaptive consequence of a developmental constraint caused by the architecture of tristyly in Pontederiaceae.

A simple genetic architecture and low constraint allow rapid floral evolution in a diverse and recently radiating plant genus.

Genetic correlations among different components of phenotypes, especially those resulting from pleiotropy, can constrain or facilitate trait evolution. These factors could especially influence the evolution of traits that are functionally integrated, such as those comprising the flower. Indeed, pleiotropy is proposed as a main driver of repeated convergent trait transitions, including the evolution of phenotypically similar pollinator syndromes. We assessed the role of pleiotropy in the differentiation of floral and other reproductive traits between two species - Jaltomata sinuosa and J.umbellata (Solanaceae) - that have divergent suites of floral traits consistent with bee and hummingbird pollination, respectively. To do so, we generated a hybrid population and examined the genetic architecture (trait segregation and quantitative trait locus (QTL) distribution) underlying 25 floral and fertility traits. We found that most floral traits had a relatively simple genetic basis (few, predominantly additive, QTLs of moderate to large effect), as well as little evidence of antagonistic pleiotropy (few trait correlations and QTL colocalization, particularly between traits of different classes). However, we did detect a potential case of adaptive pleiotropy among floral size and nectar traits. These mechanisms may have facilitated the rapid floral trait evolution observed within Jaltomata, and may be a common component of rapid phenotypic change more broadly.

Grapevine virus L: a novel vitivirus in grapevine

Vitiviruses are ssRNA(+) viruses in the family Betaflexiviridae (subfamily Trivirinae). There are currently 10 ICTV recognized virus species in the genus; nevertheless, the extended use of NGS technologies is rapidly expanding their diversity and official recognition of six more have been proposed recently. Here, we present the characterization of a novel virus from grapevine, which fits the genomic architecture and evolutionary constraints to be classified within the Vitivirus genus. The detected virus sequence is 7607 nt long, including a typical genome organization of ORFs encoding a replicase (RP), a 22 kDa protein, a movement protein, a coat protein (CP) and a nucleic acid binding protein. Phylogenetic analyses based on the predicted RP and CP proteins unequivocally place the new virus within the Vitivirus genus. Multiple independent RNAseq data confirmed the presence of the detected virus in berries at diverse developmental stages. Additionally, we detected, confirmed, and assembled virus sequences from grapevine samples of distinct cultivars from America, Europe, Asia and Oceania, sharing 74.4%–97.8% nt identity, suggesting that the identified virus is widely distributed and diverse. We propose the name grapevine virus L (GVL) to the detected Vitivirus.

Security is an architectural design constraint

In state-of-the-art design paradigm, time, space and power efficiency are considered the primary design constraints. Quite often, this approach adversely impacts the security of the overall system, especially when security is adopted as a countermeasure after some vulnerability is identified. In this position paper, we motivate the idea that security should also be considered as an architectural design constraint in addition to time, space and power. We show that security and efficiency objectives along the three design axes of time, space and power are in fact tightly coupled while identifying that security stands in direct contrast with them across all layers of architectural design. We attempt to prove our case utilizing a proof-by-evidence approach wherein we refer to various works across literature that explicitly imply the eternal conflict between security and efficiency. Thus, security has to be treated as a design constraint from the very beginning. Additionally, we advocate a security-aware design flow starting from the choice of cryptographic primitives, protocols and system design.

Parallel Enumeration of Custom Instructions Based on Multidepth Graph Partitioning

Automatic generation of custom instructions is the key to the extensible processors. The generation of custom instructions includes two crucial steps: 1) custom instruction enumeration and 2) custom instruction selection. This letter focuses on the custom instruction enumeration step. Enumerating all custom instruction candidates satisfying architectural constraints from an application graph is a computationally difficult problem. Considering the high complexity of the custom instruction enumeration, we propose a simple but efficient parallel search method based on multidepth graph partitioning for enumerating custom instructions. Experimental results show that the proposed method can give near-linear speedup and outperforms the latest parallel methods.

Understanding the cyclic response of RC walls with setback discontinuities through a finite element model and a strut-and-tie model

Slender RC walls are often used in Chile and commonly, due to architectural constraint, the length of walls increases (setback) between floors designated for parking space and upper floors. These types of elements are commonly called flag walls. In this research, the behavior of slender reinforced concrete walls with a constant axial load and a cyclic lateral displacement is numerically studied, in order to compare the results obtained with previous tests. Two different model alternatives are considered: a finite element model and a strut-and-tie model. The selected models allow understanding local response, as well as, distribution of internal forces, which is also relevant information for wall design and detailing. The studied finite element model, based on quadrilateral elements with 3 degrees of freedom per node (2 translational and 1 rotation) and a model of smeared reinforced concrete material based on a rotating angle approach, is able to correctly capture the global response, showing the capacity, degradation and failure mode obtained in the tests. On the other hand, a parametric analysis is performed for models of walls with higher aspect ratio (tall buildings) with small discontinuities, showing a larger impact in deformation capacity due to the high concentration of damage at the discontinuity. These results indicate that in 25-floor high walls (or taller) a reduction of displacement capacity of 40% for discontinuities located at the first floor could be observed. In addition, by incorporating the effect of the slabs into the model, the results indicate that a pure flexure model is an adequate and sufficient tool for analysis. Finally, a strut-and-tie model is also proposed for each direction of the lateral load, whose results are compared with the estimated load calculated with the strains measured by photogrammetry. The considered strut-and-tie model for the case of lateral load with tension in the continuous wall boundary is similar to the wall without discontinuity, which is consistent with the measured strains. For both lateral loading directions, the estimated forces of the horizontally distributed bars and boundary reinforcements are consistent with photogrammetry in the lower zone of the wall, where cracking is relevant. The strut-and-tie model also adequately interprets the effect of the discontinuous bar on the discontinuous boundary of the wall. All these results can help designing and detailing flag walls.

Model-based documentation of dynamicity constraints for collaborative cyber-physical system architectures: Findings from an industrial case study

Collaborative cyber-physical systems form highly dynamic networks, consisting of collaborating individual systems at run-time. These networks provide functionality that goes beyond the functionality of the individual systems that are part of the network. The availability of such collaborative functionalities depends not only on the individual systems’ behaviors but also on the current morphology of the network (i.e., the architecture of the overall network that defines what kind of systems and how many systems are actually partaking in the collaboration at that moment). It is of importance to thoroughly consider the possible morphologies of the network of cyber-physical systems during the development of the individual systems as these are sources for requirements as well as design decisions. These requirements and design decisions must be associated to the particular morphologies they are applicable to in order to ensure traceability and comprehensibility between the morphology of the network of cyber-physical systems and the individual systems. Hence, we aim at defining an orthogonal model which allows to document dynamicity constraints and therefore restrain the potential morphologies a network can take. This paper contributes results from an exploratory case study conducted in the industry automation domain. In the case study, an existing variability modeling approach was applied to the development of a network of autonomous transport robots. Based on the variability modeling approach an orthogonal dynamicity constrained model was defined and evolved to fit industry's needs. Results show that the use of an orthogonal model for dynamicity constraints can improve the development of cyber-physical systems designed to participate in collaborative networks.

Spandrels and trait delimitation: No such thing as "architectural constraint".

Forty years ago, Gould and Lewontin used the metaphor of a building's "spandrels" to highlight that organismal traits could be the inevitable consequence of organismal construction, with no alternative configurations possible. Because adaptation by natural selection requires variation, regarding a trait incapable of variation as an adaptation could be a serious error. Gould and Lewontin's exhortation spurred biologists' efforts to investigate biases and limitations in development in their studies of adaptation, a major methodological advance. But in terms of the metaphor itself, over the past 40 years there are virtually no examples of "spandrels" in the primary literature. Moreover, multiple serious confusions in the metaphor have been identified and clarified, for example, that the "spandrels" of San Marco are pendentives, and pendentives are perfect examples of adaptation. I look back over the sparse empirical fruits of the "spandrels" metaphor, and ask what the clarifications of the past 40 years mean for biological theory and practice. I conclude that if there is anything to be rescued from the clarified spandrels metaphor, it is not "constraint" at all. Instead, it is the still-unresolved issue of trait delimitation, which is how to parse organisms into subsets that are tractable and biologically appropriate for study.

A survey of load balancing in distributed systems

With the technological progress, distributed systems are widely used for parallel processing of computationally intensive applications with heterogeneous computing needs. Such environments require effective load balancing (LB) strategies that consider both algorithmic and architectural constraints. Indeed, the efficient load balancing of applications is crucial in order to reach high performance in parallel and distributed systems. By and large, the objective of load balancing is to find a judicious and suitable workload distribution in order to reduce as much as possible the load difference between the computational resources of the network. The proposed work presents a rigorous survey of the relevant existing load balancing techniques in several types of distributed systems. A detailed classification, the strengths and weaknesses of these techniques have been investigated according to the general characteristics of the underlying systems. We also present the main issues and features of fault tolerance and reliability for load balancing in distributed systems.

Food Web Topology and Nested Keystone Species Complexes

Important species may be in critically central network positions in ecological interaction networks. Beyond quantifying which one is the most central species in a food web, a multinode approach can identify the key sets of the most central n species as well. However, for sets of different size n, these structural keystone species complexes may differ in their composition. If larger sets contain smaller sets, higher nestedness may be a proxy for predictive ecology and efficient management of ecosystems. On the contrary, lower nestedness makes the identification of keystones more complicated. Our question here is how the topology of a network can influence nestedness as an architectural constraint. Here, we study the role of keystone species complexes in 27 real food webs and quantify their nestedness. After quantifying their topology properties, we determine their keystone species complexes, calculate their nestedness, and statistically analyze the relationship between topological indices and nestedness. A better understanding of the cores of ecosystems is crucial for efficient conservation efforts, and to know which networks will have more nested keystone species complexes would be a great help for prioritizing species that could preserve the ecosystem’s structural integrity.

Building irregularity issues and architectural design in seismic areas

When designing buildings in seismic areas, choices of the architectural designer heavily influences seismic structural performances. Namely, building morphology may lead to complex seismic responses as it occurs when building plan and elevation become irregular. Typical irregularities are due to architectural, functional and distribution constraints, thus leading to plan or vertical or combined plan/vertical irregularities. A frequent plan-wise irregularity arises when earthquake resistant structures, such as cores and shear walls, are concentrated on one side of the building plan, while vertical irregularity often arises from the presence of soft stories especially located at the ground level or, less frequently, at an intermediate level.In the last decades, some trends in architectural design, such as Deconstructivism and other contemporary theories, worked in pursuing architectural solutions based on the concept of “deconstruction” in place of “construction”, favoring non-rigid schemes, non-regular shapes and, more generally, avoiding geometric rules and classical canons of symmetry and regularity. In this paper the above issues are investigated with the goal of assessing effects of irregularity conditions, introduced by the architectural design, on the building seismic performances with the aim at not forbidding the designer ambitions but at making him aware of the effects of his architectural choices

Towards Digital Transformation in Fashion Retailing: A Design-Oriented IS Research Study of Automated Checkout Systems

Automated checkout systems promise greater sales due to an improved customer experience and cost savings because less store personnel is needed. The present design-oriented IS research study is concerned with an automated checkout solution in fashion retail stores. The implementation of such a cyberphysical system in established retail environments is challenging as architectural constraints, well-established customer processes, and customer expectations regarding privacy and convenience impose limits on system design. To overcome these challenges, the authors design an IT artifact that leverages an RFID sensor infrastructure and software components (data processing and prediction routines) to jointly address the central problems of detecting purchases in a reliable and timely fashion and assigning these purchases to individual shopping baskets. The system is implemented and evaluated in a research laboratory under real-world conditions. The evaluation indicates that shopping baskets can indeed be detected reliably (precision and recall rates greater than 99%) and in an expeditious manner (median detection time of 1.03 s). Moreover, purchase assignment reliability is 100% for most standard scenarios but falls to 42% in the most challenging scenario.

Architecture conformance analysis using model‐based testing: A case study approach

SummaryContext: The architectural drift problem defines the discrepancy between the architecture description and the code. Deviations of the code from the architecture can occur if architectural constraints as defined in the architectural models are not implemented in the code. For large‐scale systems, manually checking the consistency of the architecture with the code is not trivial and cumbersome.Objective: The overall objective of this paper is to propose and analyze the effectiveness and practicality of an architecture conformance analysis approach using model‐based testing (ACAMBT) approach for checking the consistency between architectural models and the code. Hereby, we consider the case whereby the architecture is assumed correct, and the code needs to align with the architecture.Method: We propose a model‐based testing that uses architectural views to automatically derive test cases for checking the architectural constraints in the code. We have evaluated the approach and the corresponding toolset for a real industrial case study using a systematic case study protocol. Further, we have adopted exhaustive fault‐injection techniques to detect the constraint violations.Results: The evaluation of the approach on real code showed that deviations with the architectural constraints could be easily detected in the code.Conclusion: We can conclude that ACAMBT is effective for identifying inconsistencies between the architecture views and the code for the defined view constraints. Our survey study with practitioners showed that adopting the ACAMBT approach is practical and easy to use. The approach as such can be considered as a complimentary tool to the existing testing and reflexion modeling approaches.

Location-based trustworthy services recommendation in cooperative-communication-enabled Internet of Vehicles

With the development of the Internet of Vehicles (IoV), several potential convenient applications, e.g., road safety and security, streaming services, traffic monitoring and driving comfort, have been proposed in recent years. However, the discovery and dissemination of convenient applications requires communication among service providers and service requesters through constrained networks. As an intelligent integrated network architecture, IoV suffers in terms of network data collection, real-time data interaction and sufficient data sharing due to the intrinsic network architecture constraints. In addition, because the implemented network access technologies and communication protocols are not uniform, the facilities involved in the IoV lack a unified communication protocol stack and data interface, which complicates the interconnection and cooperative communication in the whole network. To address these issues, a proprietary cooperative communication architecture and protocol stack are designed for the IoV. On this basis, a location-based trustworthy services recommendation method is developed to satisfy a user's personalized and precise service requirements. Finally, the implementation of the proposed cooperative communication architecture and protocol stack and the location-based trustworthy services recommendation method are discussed, and a performance evaluation conducted via an extensive set of experiments is presented.

Experimental cyclic response of RC walls with setback discontinuities

After the 2010 Maule, Chile, earthquake (Mw 8.8), several reinforced concrete (RC) buildings presented damage in some walls (crushing of concrete, buckling and fracture of steel reinforcement). These buildings had been designed according to the up-to-date seismic standards in the country and were not expected to suffer damage as severe as what was observed. Common features of the damaged walls were: little or no confinement at the wall ends; relatively high axial load; narrow thicknesses (below 200 mm); and discontinuities in height. Slender RC walls are often used in Chile and commonly, due to architectural constraints, the length of the walls changes between floors designated for parking use and the upper floors, creating a setback in the lower levels. These types of walls are commonly called “flag walls”. The problem of discontinuity has not been investigated experimentally and therefore it is necessary to observe its impact in RC walls. Four structural wall specimens were designed, one with no discontinuity and the other three with different sizes of the setback. They were tested under a nominal constant axial load of 0.1f'cAg and cyclic lateral loads increasing at specific drift levels. Conventional instrumentation and photogrammetry were used to monitor the tests. The experimental results show that the impact of the setback, for the sizes tested, is not significant for the strength but it is relevant for the strength degradation and deformation capacity. Strains in the extreme fibers, curvature and principal strains are studied using photogrammetry. It is found that the plastic hinge length increases with drift, but it remains constrained to the setback region. Another discontinuity is found around the reinforcement of the setback where large concentration of strains can cause premature failure of the wall.

Adopting Robotic Systems to Enhance Vibration Control of Footbridges

With innovation and aesthetics playing leading roles, the landscape of footbridge design continues to evolve towards lightweight, landmark structures, increasing the emphasis on mitigating lively dynamic responses. To satisfy architectural constraints, auxiliary control devices are being used to control the response under infrequent peak-loading events. Nearly all implemented control devices are permanent installations of passive systems, such as viscous dampers or tuned mass dampers (TMDs), that are tuned to a particular structural property and hence specific to the particular application. Recently, the concept of deployable, autonomous control systems has been presented, in which a robotic platform is combined with an active control device to yield a system that is capable of providing short-term control for a range of structures. This concept is particularly attractive in relation to footbridge applications, where the systems can be deployed during predictable peak-loading events such as marathons or used with temporary footbridges where the need for control depends on the intended use. In this paper, analytical modeling of a prototype system is presented to validate experimental identification. Furthermore, the role of the control–structure interaction (CSI) is described and compensated for through an active controller formulation and the use of a position feedback controller for disturbance rejection. The performance of the prototype system is evaluated experimentally and assessed relative to an equivalent passive TMD device. The experimental study validates the controller formulation and demonstrates the effectiveness of the prototype system.

AN EVALUATION PIPELINE FOR INDOOR LASER SCANNING POINT CLOUDS

Abstract. The necessity for the modelling of building interiors has encouraged researchers in recent years to focus on improving the capturing and modelling techniques for such environments. State-of-the-art indoor mobile mapping systems use a combination of laser scanners and/or cameras mounted on movable platforms and allow for capturing 3D data of buildings’ interiors. As GNSS positioning does not work inside buildings, the extensively investigated Simultaneous Localisation and Mapping (SLAM) algorithms seem to offer a suitable solution for the problem. Because of the dead-reckoning nature of SLAM approaches, their results usually suffer from registration errors. Therefore, indoor data acquisition has remained a challenge and the accuracy of the captured data has to be analysed and investigated. In this paper, we propose to use architectural constraints to partly evaluate the quality of the acquired point cloud in the absence of any ground truth model. The internal consistency of walls is utilized to check the accuracy and correctness of indoor models. In addition, we use a floor plan (if available) as an external information source to check the quality of the generated indoor model. The proposed evaluation method provides an overall impression of the reconstruction accuracy. Our results show that perpendicularity, parallelism, and thickness of walls are important cues in buildings and can be used for an internal consistency check.

Informal use of restraint in nursing homes: A threat to human rights or necessary care to preserve residents’ dignity?

Use of restraint in nursing homes is highly controversial and fundamentally transgresses human rights and freedom of movement and choice. While different forms of formal restraint use in nursing homes are broadly delineated, the use of informal restraint is less understood. The aim of this article is to identify different kinds of informal restraint, and how staff use informal restraint under which circumstances. This article illuminates informal restraint use based on an ethnographic study in four nursing homes in the Western part of Norway. We have identified five different forms of informal restraint use which are as follows: (1) diversion of residents' attention; (2) white lies; (3) persuasion and interpersonal pressure; (4) offers and finally (5) threats. These different forms of informal restraint are actions by staff against residents' will, limiting residents' freedom of movement and their personal preferences. In addition, we have identified 'grey-zone restraint' which comprises actions by staff towards residents which lie in-between formal and informal restraint. The use of informal restraint can be explained by institutional circumstances such as location, architecture and institutional collectivist constraints in relation to care work. Moreover, and paradoxically, informal restraint can be explained as a consequence of neo-liberal policies with establishment of extended premises for freedom of movement and practices of resident preferences in nursing homes. Informal restraint practices call into question whether these practices are compatible with fundamental human rights and the preservation of residents' dignity.