Insight into Saturated Hydraulic Conductivity of Cemented Paste Backfill Containing Polycarboxylate Ether-Based Superplasticizer

Recycling of tailings in the form of cemented paste backfill (CPB) is a widely adopted practice in the mining industry. Environmental performance is an important design criterion of CPB structures. This environmental performance of CPB is strongly influenced by its saturated hydraulic conductivity (permeability). Superplasticizers are usually added to improve flowability, but there is a limited understanding of their influence on the hydraulic properties of the CPB. This paper presents new experimental results on the variations of the hydraulic conductivity of CPB containing polycarboxylate-based superplasticizer with different compositions and curing conditions. It is found that the hydraulic conductivity of the CPB decreases with the addition of superplasticizer, which is beneficial to its environmental performance. The reduction is largely attributable to the influence of the ether-based superplasticizer on particles mobility and cement hydration. Moreover, both curing temperature and time have correlations with the hydraulic conductivity of CPB containing superplasticizer. In addition, the presence of sulfate and partial replacement of PCI with blast furnace slag reduces the hydraulic conductivity. The variations are mainly due to the changes in the pore structure of the CPB. The new results discussed in this manuscript will contribute to the design of more environmental-friendly CPBs, which is essential for sustainable mining.

Homogenising the Design Criteria of a Community Battery Energy Storage for Better Grid Integration

Historically, minimum system demand has usually occurred overnight. However, in recent years, the increased penetration of rooftop photovoltaic systems (RPVs) has caused an even lower demand at midday, forcing some of the conventional generators to shut down only hours before the evening peak demand period. This further complicates the job of power system operators, who need to run the conventional generator at the minimum stable level at the midday low-demand period so that they can reliably supply power during the peak periods. Employing a community battery storage system can alleviate some of the technical issues caused by the high penetration of RPVs. This paper proposed a design criterion for community battery energy storage systems and employed the battery for the improvement of the duck curve profile and providing the desired level of peak-shaving. Furthermore, remote communities with high penetration of RPVs with a community battery energy storage can achieve the desired level of self-sufficiency. To this end, this study recommends and confirms an applicable design criterion for community battery energy storage. The study shows that the suitable size of community battery storage should be based on the community’s daily excess generation and consumption requirements. The results of various scenarios performed on the proposed design criterion show the extent to which the desired objectives of peak-shaving, duck curve mitigation, and self-sufficiency can be achieved.

Constant stress arches and their design space

It is generally accepted that an optimal arch has a funicular (moment-less) form and least weight. However, the feature of least weight restricts the design options and raises the question of durability of such structures. This study, building on the analytical form-finding approach presented in Lewis (2016. Proc. R. Soc. A 472 , 20160019. ( doi:10.1098/rspa.2016.0019 )), proposes constant axial stress as a design criterion for smooth, two-pin arches that are moment-less under permanent (statistically prevalent) load. This approach ensures that no part of the structure becomes over-stressed under variable load (wind, snow and/or moving objects), relative to its other parts—a phenomenon observed in natural structures, such as trees, bones, shells. The theory considers a general case of an asymmetric arch, deriving the equation of its centre-line profile, horizontal reactions and varying cross-section area. The analysis of symmetric arches follows, and includes a solution for structures of least weight by supplying an equation for a volume-minimizing, span/rise ratio. The paper proposes a new concept, that of a design space controlled by two non-dimensional input parameters; their theoretical and practical limits define the existence of constant axial stress arches. It is shown that, for stand-alone arches, the design space reduces to a constraint relationship between constant stress and span/rise ratio.

Conjugated Polymers with Controllable Interfacial Order and Energetics enable Tunable Heterojunctions in Organic and Colloidal Quantum Dot Photovoltaics

Conjugated polymers are widely used as photoactive and transport layers in organic and hybrid photovoltaics (PV), where the energetics of polymers are a key design criterion. Here, we show that...

Dynamic event-triggered fault detection filter design for dynamical systems under fading channels

This article investigates the dynamic event-triggered fault detection filter (FDF) design problem for linear continuous-time networked systems, considering the fading channels phenomenon and randomly occurring faults. A dynamic event-triggered mechanism (ETM) is introduced to reduce the network bandwidth occupation more efficiently by utilizing an internal variable which can enlarge the event-triggered intervals. Besides, the Zeno phenomenon is eliminated fundamentally by ensuring that the event-triggered intervals are positive lower bounded. After that, sufficient conditions are derived to guarantee the stochastic stability of the residual system with a desired [Formula: see text] performance and the co-design criterion of the FDF and the dynamic ETM is developed. Finally, an unmanned surface vehicle (USV) system is used to illustrate the applicability of the presented approach.

Electromagnetic Spectrum of the Corona Discharge and Their Fundamental Frequency

Historically, the Electromagnetic Compatibility (EMC) began with the disturbances at the radio navigation systems generated by the electrical power distribution lines; hence it was referred to as Radio Interference (RI). This disturbance is an Electromagnetic Interference (EMI). Although this type of EMI has been studied since the first decades of the past century, it still maintains a continued interest of the researchers, especially with the Corona Discharge (CD), generated by High Voltage Direct Current (HVDC) systems. Because of its design criterion and the concern that this phenomenon may affect the new radio communication systems in the very high frequency (VHF), ultra high frequency (UHF), and microwave bands, interest in their studies continues. In this chapter, an analysis of the electromagnetic spectrum of the CD is presented. The CD is generated at a short transmission line located within a semi-anechoic chamber. To be sure of the phenomenon, the CD is identified by its current pulse, which is well studied. The instruments used are an oscilloscope of 2 GHz and 2 GS/s, a spectrum analyzer, and an EMI test receiver. The results show that the CD concentrates its energy at frequencies below 70 MHz. In the UHF band, only narrowband signals very separated were found, with levels that cannot affect radio communication systems.

Cities after pandemic: enabling social distancing as a new design standard to achieve urban immunity

Motives: COVID-19 pandemic has caused worldwide implementation of unprecedented measures of physical distancing to decrease the potential of the COVID-19 infection. As cities respond to closure measures in order to flatten the infection curve, the challenges associated with the spread of the epidemic and the increasing numbers of infected and deaths that compel us to fundamentally rethink the formation of our cities, especially their streets, the research presents an urban review of the impact of the pandemic on cities and find solutions to recover, achieve a safe and sustainable healthy environment, and prepare better for any pandemic that may occur in the future, the research seeks to strengthen the theory of prevention, which the research proposes to call (urban immunity) by including social distancing as a design criterion in the city that has proven effective in flattening the curve. Aims: This paper focuses on the mechanisms related to sustainable mobility after COVID-19 in shaping urban mobility and initiating a green transformation in urban transportation rapidly by decarbonizing and promoting cycling and walking across all over the city. The research methodology depends on identifying the most important urban problems that Al-Dhubat Street suffers from and proposing solutions that reduce dependence on private transportation and move towards sustainable mobility as an important step in strengthening urban prevention against any epidemics that may occur in the future, and then testing indicators on the Al-Dhubat Street to identify effective indicators. Results: The research concluded that social distancing is the way back to active mobility by relying on walking and bicycles and works to restore the right of pedestrians in the streets and sidewalks instead of cars and thus achieve sustainable urban development, which enhances the urban immunity of the city against any other epidemics may occur in the future. With the proposed interventions on Al-Dhubat Street we can keep car use low and promote walking and cycling for a sustainable, equitable, habitable, and healthy community after the pandemic.

The infinity stadium: Intensifying the sublime in post-event stadia

<p>The Stadium is a blend of commercialism, functionality, regulation and iconicism. At the height of its power, a Stadium is an unrivalled example of the Sublime functioning at a massive scale for a collective and for individuals simultaneously. Every year, large-scale stadia are built for events such as Olympic Games or World Cups which then become underused or even abandoned after the event has finished. Despite this, these facilities continue to be built. This thesis argues that the challenge then, is to design the Sublime into the post-event stadia architecture. This thesis looks to explore architectural design methods that invest the post-event stadia with the Sublime. The aim is to intensify the Sublime, often found at the height of the event, in post-event situations. Explorations in scale and programming are used to test such intensifications. Can the Sublime – which, to paraphrase Burke, is “the strongest of emotions causing astonishment because of unimagined eloquence, greatness, significance, or power, and which is experienced by the user as awe, wonder or even dread, fear and terror” - be found after the event? This research uses iterative design experimentation to tease out the Sublime at three scales: that of an installation, then a domestic scale and then an urban-public scale. This research ultimately looks to create a project that uses the Sublime as a main driver and design criterion for creating a Stadium that is as effective at low capacity as it is at full capacity through the enticement of the Sublime.</p>

The infinity stadium: Intensifying the sublime in post-event stadia

<p>The Stadium is a blend of commercialism, functionality, regulation and iconicism. At the height of its power, a Stadium is an unrivalled example of the Sublime functioning at a massive scale for a collective and for individuals simultaneously. Every year, large-scale stadia are built for events such as Olympic Games or World Cups which then become underused or even abandoned after the event has finished. Despite this, these facilities continue to be built. This thesis argues that the challenge then, is to design the Sublime into the post-event stadia architecture. This thesis looks to explore architectural design methods that invest the post-event stadia with the Sublime. The aim is to intensify the Sublime, often found at the height of the event, in post-event situations. Explorations in scale and programming are used to test such intensifications. Can the Sublime – which, to paraphrase Burke, is “the strongest of emotions causing astonishment because of unimagined eloquence, greatness, significance, or power, and which is experienced by the user as awe, wonder or even dread, fear and terror” - be found after the event? This research uses iterative design experimentation to tease out the Sublime at three scales: that of an installation, then a domestic scale and then an urban-public scale. This research ultimately looks to create a project that uses the Sublime as a main driver and design criterion for creating a Stadium that is as effective at low capacity as it is at full capacity through the enticement of the Sublime.</p>