The Digital Currency of China’s Central Bank:Digital Currency Electronic Payment(DCEP)

DCEP is the Chinese version of Central Bank Digital Currency(CBDC).It is the only legal digital currency in China and meets four conditions:(a)it is issued by the central bank;(b)it is digitized;(c)it is account and wallet based;(d)it is oriented towards the general public.As a retail central bank digital currency,it has three main technical features:a“tiered limit arrangement”(small-scale payments can be made anonymously while large-scale payments cannot),a“two-tier operating system”(as with the central bank-commercial bank traditional model),and a“dual offline payment system”(supporting both parties of the transaction).Compared with CBDCs in other countries,China’s DCEP has smaller economic impacts,more obscure strategic goals,and more scarce technical details.But its progress in testing is ahead of central banks of other countries.This article is based on public information and is intended to explain what DCEP is and why and how it was developed.It also offers suggestions for future research.

Theoretical and numerical simulation investigation of deep hole dispersed charge cut blasting

Drilling and blasting methods have been used as a common driving technique for shallow-hole driving and blasting in rock roadways.With the advent of digital electronic detonators and the need for increased production efciency,the traditional blasting design is no longer suitable for deep hole blasting.In this paper,a disperse charge cut blasting method was proposed to address the issues of low excavation depth and high block rate in deep hole undercut blasting.First,a blasting model was used to illustrate the mechanism of the deep hole dispersive charge cut blasting process.Then,continuous charge and dispersed charge blasting models were developed using the smooth particle hydrodynamics-fnite element method(SPHFEM).The cutting parameters were determined theoretically,and the cutting efciency was introduced to evaluate the cutting efect.The blasting efects of the two charging models were analyzed utilizing the evolution law of rock damage,the number of rock particles thrown,and the cutting efciency.The results show that using a dispersed charge improves the cutting efciency by about 20%and the rock breakage for the deep hole cut blasting compared to the traditional continuous charge.In addition,important parameters such as cutting hole spacing,cutting hole depth and upper charge proportion also have a signifcant impact on the cutting efect.Finally,the deep hole dispersed charge cut blasting technology is combined with the digital electronic detonator through the feld engineering practice.It provides a reference for the subsequent deep hole cutting blasting and the use of electronic detonators in rock roadways.

Field Test Summary of Two Kinds of Electronic Detonator for Seismic Exploration

Electronic detonators are widely used because of their advantages in real-time supervision of the whole life cycle (Zang, 2022). Due to the high requirements of the time difference synchronization between the electronic initiation system and the seismic wave recording system, the Electronic detonator has not been widely used for Seismic exploration (Yang, 2020). This paper expounds the systematic and scientific test method from the aspects of the comprehensive performance of electronic detonators for exploration, the compatibility between the electronic detonator initiation system and the geophysical blasting machine system, the constraints of the geophysical explosion-related collaborative Danling managment cloud platform, and the quality of data collected by electronic detonator blasting in wells., and based on the analysis of the test results, the problems that need to be improved in the application of electronic detonators and detonation systems in the large-scale production of geophysical prospecting industry are put forward. .

Digital Power Electronics

High frequency switching circuits can effectively increase the power density, efficiency, reliability and flexibility, and reduce power losses and equipment cost. Consequently, high-frequency switching circuits have been paid much attention in recent decades. These performances are thoroughly different from traditional analogue control systems. Till now there is no suitable theory to describe the characteristics of the switching circuits and systems. A new theory entitled 'Digital Power Electronics' presents the clue of switching operation (switching period T=1/f,f is the switching frequency) and the pumping-filtering process,resonant operation and softswitching methodology,and researched the rules of power switching circuits and systems. The new parameters Energy Factor (EF), Pumping Energy (PE), Stored Energy (SE), Capacitor- Inductor stored energy Ratio (CIR) and time constants r and r d. Using these new parameters,ZOH/FOH/SOH and the z-transform can well describe the characteristics of power switching circuits and systems.