Proposed Design Principles Research Articles

Molecular Design of Three-Dimensional Metal-Free A(NH4)X3 Perovskites for Photovoltaic Applications

The intense research activities on the hybrid organic–inorganic perovskites (HOIPs) have led to the greatly improved light absorbers for solar cells with high power conversion efficiency (PCE). However, it is still challenging to find an alternative lead-free perovskite to replace the organohalide lead perovskites to achieve high PCE. This is because both previous experimental and theoretical investigations have shown that the Pb2+ cations play a dominating role in contributing the desirable frontier electronic bands of the HOIPs for light absorbing. Recent advances in the chemical synthesis of three-dimensional (3D) metal-free perovskites, by replacing Pb2+ with NH4+, have markedly enriched the family of multifunctionalized perovskites (Ye et al., Science2018, 361, 151−15530002249). These metal-free perovskites possess the chemical formula of A(NH4)X3, where A is divalent organic cations and X denotes halogen atoms. Without involving transition-metal cations, the metal-free A(NH4)X3 perovskites can entail notably different frontier electronic band features from those of the organohalide lead perovskites. Indeed, the valence and conduction bands of A(NH4)X3 perovskites are mainly attributed by the halogen atoms and the divalent A2+ organic cations, respectively. Importantly, a linear relationship between the bandgaps of A(NH4)X3 perovskites and the lowest unoccupied molecular orbital energies of the A2+ cations is identified, suggesting that bandgaps can be tailored via molecular design, especially through a chemical modification of the A2+ cations. Our comprehensive computational study and molecular design predict a metal-free perovskite, namely, 6-ammonio-1-methyl-5-nitropyrimidin-1-ium-(NH4)I3, with a desirable bandgap of ∼1.74 eV and good optical absorption property, both being important requirements for photovoltaic applications. Moreover, the application of strain can further fine-tune the bandgap of this metal-free perovskite. Our proposed design principle not only offers chemical insights into the structure–property relationship of the multifunctional metal-free perovskites but also can facilitate the discovery of highly efficient alternative, lead-free perovskites for potential photovoltaic or optoelectronic applications.

Supporting Student Engagement Through the Gamification of Learning Activities: A Design-Based Research Approach

The application of gamification for educational purposes has been widely reported with mixed results. Successful application, in most cases, is subjective and failures or mistakes are often downplayed when in reality, there is much to be learnt from these (failed) attempts. Despite the unique nature of each context and target audience, transferable principles that guide implementation are present and should be reported. This study applied a design-based research approach which offers a contextually sensitive, theoretically driven approach to the design and refinement of educational interventions. Through iterative implementations and qualitative data collection, over a 2-year period, we report on the process and outcome of gamifying the learning activities in an Industrial Psychology module to facilitate student engagement. The primary contribution of the study are proposed design principles for practitioners and researchers based on the lessons learned in this process. These highlight key considerations for applying gamification to support student engagement.

Hydrophilic domains compose of interlocking cation-π blocks for constructing hard actuator with robustness and rapid humidity responsiveness

Biomimetic actuators have seemingly infinite potential for use in previously unexplored areas. However, large stresses and a rapid water response are difficult to realize in soft actuators, owing to which their practical applicability is currently limited. In this paper, a new method for designing and fabricating humidity-responsive sturdy hard actuator. By combining a rigid matrix and hydrophilic water domains consisting of dynamic interlocking cation-π blocks, high-performance polymer actuator was synthesized that swell rapidly in response to a water gradient in their environment, resulting in unprecedentedly large stresses. More critically, the strong interlocking cation-π blocks reform and the intermolecular distance is reduced when the water is removed, allowing the deformed actuator to revert its original shape. The proposed design principle can potentially be extended to produce different types of sturdy actuators with rapid water responsiveness.

Principles and Skills of Product Design to Promote Green Behavior

Promoting green behavior through product design is a simple way to reduce human impact on the environment. Based on Design for Sustainable Behavior and Behavior Theory, this study aims to propose design principles and techniques to effectively promote green behavior, and take household appliances as the empirical object of research, and introduce Analytical Hierarchy Process to overcome the problem in multi-criteria decision making of choosing the best design principles and skills under limited resources. The empirical results show that “Design for Green Behavior of Perceived Behavioral Control” is the key to promote energy-saving behavior of household appliances. Relevant designers can consider the weight value of the research results, and effectively design products to promote green behavior.

Vernacular rural heritage in Turkey: an intuitional overview for a new living experience

PurposeThe purpose of this paper is to emphasize passive energy refurbishment of vernacular building heritages and propose new application principles of sustainability from these vernacular heritages into contemporary architecture.Design/methodology/approachThis paper is based on a research project (The Creation of a Prototype Project within the Application of Traditional Methods in Kastamonu, Küre Rural Settlements, 2017), through which vernacular architecture examples were analyzed, projecting for future interpretations for rural environments. Defining vernacular rural design principles is centrally important for the purposes of this project. As a case study from the Black Sea Region in Turkey, this example is investigated, and the outcomes of the analysis are used to reproduce in contemporary architectural terms the energy efficiency and rural patterns of the flexible rural house experience.FindingsThe research provides design principles for developing a new living experience in rural environments. The overall planning and architectural analysis are made in five neighborhoods in Küre, and three of unique vernacular architecture examples are chosen according to several criteria defined in “Kastamonu-Küre Ersizlerdere Village Design Guideline Project, 2014” to get the optimum data. Materials, orientation, form, spatial organization and building's indoor-outdoor relationship were analyzed by Autodesk's “Ecotect Analysis” simulation program.Practical implicationsResults of the proposed design principles of rural housing will be useful for new housing interpretations related to better rural development.Originality/valueWhile defining energy efficiency criteria of vernacular itself, the results of this paper suggest new local solutions to ecological building design and engage with critical regionalism principles referring to the potentials of what traditional dwellings can teach contemporary design.

Design principles for creating digital transparency in government

Under pressure to fight corruption, hold public officials accountable, and build trust with citizens, many governments pursue the quest for greater transparency. They publish data about their internal operations, externalize decision-making processes, establish digital inquiry lines to public officials, and employ other forms of transparency using digital means. Despite the presence of many transparency-enhancing digital tools, putting such tools together to achieve the desired level of digital transparency, to design entire government systems for digital transparency, remains challenging. Design principles and other design guides are lacking in this area. This article aims to fill this gap. We identify a set of barriers to digital transparency in government, define 16 design principles to overcome such barriers, and evaluate these principles using three case studies from different countries. Some principles apply to projects, others to systems, yet others to entire organizations. To achieve digital transparency, before building and deploying digital solutions, government organizations should build technological and institutional foundations and use such foundations to organize themselves for transparency. The proposed design principles can help develop and apply such foundations.

Harnessing distinct deformation modes of auxetic patterns for stiffness design of tubular structures

Auxetic materials with a negative Poisson's ratio show a unique lateral expansion under tension while their deformation under shear is similar to that of normal materials. Here, we present a novel method to design the stiffness of tubular structures by exploiting these load-dependent distinct deformation modes of auxetic materials. Auxetic cutting patterns are engraved on a tube whose bending and torsional stiffness values are predicted computationally for a comprehensive set of design parameters and measured experimentally for representative designs. Results demonstrate that a wide range of bending and torsional stiffness values can be effectively achieved and controlled independently. The proposed design principle is simple and powerful, and hence can be easily extended to design the mechanical properties of non-tubular structures as well.

Design and Fabrication of Vertical Metal/TiO2/β-Ga2O3Dielectric Heterojunction Diode With Reverse Blocking Voltage of 1010 V

This work provides insight into the design principles and the reasonable construction of Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> heterojunction diode. We chose TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> grown by atomic layer deposition (ALD) as a suitable insulator with a small conduction band offset of TiO<;span style="font-size: 14.5px;"> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /<;/span> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">β</i> -Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> heterojunction and a large dielectric constant. The type-I band alignment of the TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> / <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">β</i> -Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> heterojunction was obtained using X-ray photoelectron spectroscopy (XPS). We demonstrated a high-performance vertical metal/TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> / <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">β</i> -Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> dielectric heterojunction diode with reverse blocking voltage of 1010 V and differential ON-resistance of 3.3 mΩ·cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The proposed design principles of dielectric heterojunction diode and the insulator selection can also provide a simple, effective, and feasible technology for other wideband and ultrawideband semiconductors in which bipolar doping is challenging to achieve high power device performance.

IoT Network Security: Threats, Risks, and a Data-Driven Defense Framework

The recent surge in Internet of Things (IoT) deployment has increased the pace of integration and extended the reach of the Internet from computers, tablets and phones to a myriad of devices in our physical world. Driven by the IoT, with each passing day, the Internet becomes more integrated with everyday life. While IoT devices provide endless new capabilities and make life more convenient, they also vastly increase the opportunity for nefarious individuals, criminal organizations and even state actors to spy on, and interfere with, unsuspecting users of IoT systems. As this looming crisis continues to grow, calls for data science approaches to address these problems have increased, and current research shows that predictive models trained with machine learning algorithms hold great potential to mitigate some of these issues. In this paper, we first carry out an analytics approach to review security risks associated with IoT systems, and then propose a machine learning-based solution to characterize and detect IoT attacks. We use a real-world IoT system with secured gate access as a platform, and introduce the IoT system in detail, including features to capture security threats/attacks to the system. By using data collected from a nine month period as our testbed, we evaluate the efficacy of predictive models trained by means of machine learning, and propose design principles and a loose framework for implementing secure IoT systems.

Stress-induced brittle failure of surrounding rock mass and its engineering countermeasures in the Baihetan underground powerhouse

Stress-induced brittle failures, such as spalling, slabbing, and rockburst, are common failure modes of underground caverns in high-stress zones. In the Baihetan Hydropower Station, the brittle failures, embodied as spalling, rock fracturing, and time-dependent deformation, bring new challenges to the excavation and support system design of underground caverns. Based on the New Austrian Tunneling Method, the specific design principles for the underground caverns of Baihetan Hydropower Station are proposed, the keys of which are preconditioning surrounding rock mass, reducing the excavation damage, supporting quickly in the proper sequence, and controlling loosen zones. These principles are applied during construction, and a series of excavation and support methods are developed for the key parts of the powerhouse, such as the roof arch, the rock wall of rock-bolted crane girder, the high side wall, and the partition wall of the generator pit. Data obtained from visual appearance, displacement measurement, and acoustic testing show that the proposed design principles are appropriate and that the developed excavation and support methods can control the range and depth of stress-induced failure of the surrounding rock mass.

Tailoring the Cation Lattice for Chloride Lithium‐Ion Conductors

AbstractAll‐solid‐state Li‐ion batteries require Li‐ion conductors as solid electrolytes (SEs). Li‐containing halides are emerging as a promising class of lithium‐ion conductors with good electrochemical stability and other properties needed for SEs in all‐solid‐state batteries. Compared to oxides and sulfides, Li‐ion diffusion mechanisms in Li‐containing halides are less well understood, in particular regarding the effects of Li content and cation sublattices, which can be tailored for improving Li‐ion conduction. Using first‐principles computation, a systematic study is performed on the Li‐ion conduction of known Li‐containing chlorides with close‐packed anion frameworks and a wide range of their doped compounds. A dozen potential chloride Li‐ion conductors are predicted with increased Li‐ion conductivities, and it is revealed that the Li‐ion migration is greatly impacted by the cation configuration and concentrations. By analyzing a large set of materials data, it is proposed that low Li content, low cation concentration, and sparse cation distribution increase Li‐ion conduction in chlorides, and these principles are demonstrated in designing new chloride Li‐ion conductors. This study provides insights into the effects of the cation sublattice on Li‐ion diffusion, highlights potential chloride Li superionic conductors, and proposes design principles to further develop halide Li‐ion conductors.

Wearable robotic exoskeletons: A socio-philosophical perspective on Duchenne muscular dystrophy research

AbstractRecently, several research projects in the Netherlands have focused on the development of wearable robotic exoskeletons (WREs) for individuals with Duchenne muscular dystrophy (DMD). Such research on WREs is often treated solely within the disciplines of biomedical and mechanical engineering, overlooking insights from disability studies and philosophy of technology. We argue that mainly two such insights should receive attention: the problematization of the ableism connected to the individual model of disability and the stigmatization by assistive technology. While disability studies have largely rejected the individual model of disability, the engineering sciences seem to still locate disability in an individual’s body, not questioning their own problematization of disability. Additionally, philosophy of technology has argued that technologies are not neutral instruments but shape users’ actions and perceptions. The design of WREs may convey a message about the understanding of disability, which can be comprehended as a challenge and an opportunity: stigmatization needs to be avoided and positive views on disability can be evoked. This article aims to highlight the benefits of considering these socio-philosophical perspectives by examining the case of WREs for people with DMD and proposing design principles for WREs. These principles may enhance acceptability of WREs, not only by individuals with DMD but also by other users, and help engineers to better place their work in the social context.

Design and control of an energy-efficient process for the separation of benzene/isopropanol/water ternary mixture

In a recent publication, a triple-column side-stream extractive distillation system was proposed for the separation of benzene/isopropanol/water ternary mixture using ethylene glycol as a heavy entrainer. However, the above design needs to introduce a foreign component into the separation task. In this paper, the newly proposed design principle is to make use of large liquid–liquid envelope together with pressure-sensitive distillation boundary of this ternary system for the development of an energy-efficient design consisting of a decanter and three columns operating at different pressures. In order to give reliable simulation results, a new set of UNIQUAC model parameters for this ternary system is obtained in this paper by regression from liquid-liquid and vapor–liquid equilibria data in open literatures. Simulation investigations reveal that significant savings of 63.4% in the total operating cost and 51.0% in the total annual cost can be realized by our proposed heat-integrated design flowsheet. Furthermore, overall control strategy of the proposed design has also been developed using closed-loop and open-loop sensitivity analyses for the determinations of crucial tray-temperature control points and also to make decision on holding which flow ratio(s) in the flowsheet to be fixed. Dynamic simulations demonstrate that the proposed overall control strategy is capable of holding three products at high-purity despite feed flow rate and feed composition disturbances. No online composition analyzer is required in the proposed control strategy.

The Research of Green Reuse on Old Industrial Building A Case Study of Changchun FAW

With the development of a large number of old industrial buildings, such as the relocation, transformation, demolition and other issues, how to reuse the building resources has become an urgent problem need to solve. This paper about architectural resources reuse, based on old industrial buildings in Changchun FAW, proposed using green technology to revive the vitality of old industrial buildings, at the same time, starting from the point of view of green energy-saving, proposed design principles, and recommendations about old industrial buildings green resources reuse in Changchun FAW.

Phase Transforming Based on Asymmetric Spoof Surface Plasmon Polariton for Endfire Antenna With Sum and Difference Beams

An endfire antenna with sum and difference beams is designed based on phase transforming of a proposed asymmetric spoof surface plasmon polariton (SSPP) structure. The asymmetric arrays of grooves, with different groove depths, periods, and/or duty ratios, serve as transmission structure and transmit electromagnetic (EM) waves in SSPP modes. Due to the distinct phase constants for the EM fields on the two sides of the asymmetric structures, the transformation of phase difference for the EM waves is realized. Superposition in the endfire direction for the in-phase and out-of-phase EM fields forms the endfire radiations with sum and difference beams. A design procedure is proposed where operating frequencies of the endfire antenna are predicted with the dispersion curves of the asymmetric SSPP structures and allocated by phase transformation. A prototype is implemented to validate the proposed design principle. Sum beam operating frequencies of the endfire antenna are at 5.50, 6.60, and 7.09 GHz, while difference beams appear at 6.10 and 6.90 GHz. Good agreement of the results validates the feasibility of the proposed mechanism and design procedure. The proposed endfire antenna with sum and difference beams has broad prospect in direction finding, tracking, and anti-interference applications.

Formation of Multicontinuous 3D Network Nanostructures with Increased Complexity in ABC-Type Block Copolymers.

The multicontinuous network nature of polymer nanostructures provides them with many opportunities to fabricate multifunctional materials with specific mechanical, transport, optical, and other novel properties. In this paper, we generate an effective design principle to craft a series of multicontinuous network structures with controllable channels, including multicontinuous gyroid and O70 network morphologies via the self-assembly of ABC-type block copolymers. Importantly, we achieve a much wider (∼25%) compositional range than that of AB diblock copolymers (∼3%), which would increase the widespread application of these multicontinuous polymer networks. Even for the simplest ABC linear system, this method is valid for generating multicontinuous network structures, where gyroids and O70 are found to possess large phase regions. This finding can theoretically explain the experimental observation of gyroid and O70 phases. We believe that our proposed design principle along with the calculated phase diagram provides a compelling panacea for the fabrication of multicontinuous 3D network nanostructures.

A generalized broadband coupled-line based rat-race coupler with arbitrary power division ratios and free terminated impedances

A generalized broadband coupled-line based rat-race coupler with arbitrary power division ratios and free terminated impedances is proposed in this paper. Besides, rigorous closed-form equations with respect to electrical parameters are derived in the section of analysis. Furthermore, one shorted coupled-line section and two identical open-circuited stubs are employed to achieve the requirement of wideband and miniaturization. Owing to additional design freedom, the calculation of parameters becomes much more flexible. For demonstration, a prototype for 6-dB wideband rat-race coupler centered at 1 GHz with the fractional bandwidth of 51.69% and free terminated impedances is designed, fabricated, and measured. Good agreement between the simulated and measured results can be observed, which can verify the validity of the proposed design principle.

A quasi-zero-stiffness vibration isolator using a cam mechanism with user-defined profile

This paper presents a passive quasi-zero-stiffness (QZS) vibration isolator via a cam mechanism (CM), where the cam has a user-defined profile to generate the desired force-displacement relation that yields the QZS characteristic. Without using the common configurations connecting positive and negative stiffness in parallel, this CM based QZS isolator is much simpler in structure due to utilizing fewer key components. Unlike previous studies where the high calculation complexity must be simplified by Taylor expansion for the convenience of dynamic analyses, this QZS isolator has the superiority that the ideal simplest restoring force with QZS property can be directly realized through the well-designed CM, which can eliminate the approximation error between the theoretical design and actual implementation. The nonlinear differential motion equations based on pure-cubic restoring force and both viscous and friction damping are derived and solved with the harmonic balance method, followed by the discussion of the relevant dynamic characteristics. Experiments on the fabricated physical prototype of the QZS isolator are carried out. The static results verify the proposed design principle due to the agreement between the tested and designed force-displacement curves. The vibration tests show the advantages of QZS isolator in most cases, since it can exhibit the wider isolation frequency bandwidth and much weaker resonance effect than the corresponding linear counterpart. The actual transmissibility characteristics of the QZS and linear isolators under different force and base motion excitation levels are obtained and comprehensively compared to reveal the specific isolation efficiency and how excitation amplitudes affect the vibration attenuation performance.

6G Vision: An AI-Driven Decentralized Network and Service Architecture

Recently, following the rapid commercial deployment of 5G networks, next-generation mobile communication technology (6G) has been attracting increasing attention from global researchers and engineers. 6G is envisioned as a distributed, decentralized, and intelligent innovative network. However, existing application provisioning is still based on a centralized service architecture, ubiquitous edge computing, and decentralized AI technologies have not been fully exploited. In this article, we analyze the problems faced by existing centralized service provisioning architecture, and propose design principles for a decentralized network and service architecture for a future 6G network. Finally, we discuss several open research problems to inspire readers to address these.

Cardiac energy harvesting and sensing based on piezoelectric and triboelectric designs

Cardiac implantable devices are effective both as methods of controlling irregular heartbeats in people with heart rhythm disorders and as interventional therapy for cardiac diseases. However, early failures and battery limitations of cardiac medical devices lead to periodic battery replacement surgeries for patients that are both risky and costly. Self-sustainable energy generation could significantly extend the lifetime and effectiveness of cardiac implantable devices and other implantable biomedical devices (IMDs). The human heart is a compelling in vivo energy source and is a natural battery to power IMDs. In this review, we discuss current trends of developing self-powered cardiac medical devices harvesting the energy from the heart. Based on key challenges and limitations, we propose design principles for cardiac energy harvesters and sensors. We further discuss advanced energy materials, structural and fabrication considerations, biosafety and biocompatibility, and comfortability and flexibility. Moreover, recent advances in cardiac energy harvesting and sensing devices in both in vivo and in vitro studies are reviewed and discussed. Such sustainable energy strategies based on piezoelectric and triboelectric designs provide a promising means to reduce the reliance on batteries for powering cardiac medical devices and other IMDs.