Analysis of Mobile and Internet Network Coverage: Propagation of Electromagnetic Waves and Concept of Digital Divide in Burundi

Mobile and Internet network coverage plays an important role in digital transformation and the exploitation of new services. The evolution of mobile networks from the first generation (1G) to the 5th generation is still a long process. 2G networks have developed the messaging service, which complements the already operational voice service. 2G technology has rapidly progressed to the third generation (3G), incorporating multimedia data transmission techniques. It then progressed to fourth generation (4G) and LTE (Long Term Evolution), increasing the transmission speed to improve 3G. Currently, developed countries have already moved to 5G. In developing countries, including Burundi, a member of the East African Community (ECA) where more than 80% are connected to 2G technologies, 40% are connected to the 3G network and 25% to the 4G network and are not yet connected to the 5G network and then still a process. The objective of this article is to analyze the coverage of 2G, 3G and 4G networks in Burundi. This analysis will make it possible to identify possible deficits in order to reduce the digital divide between connected urban areas and remote rural areas. Furthermore, this analysis will draw the attention of decision-makers to the need to deploy networks and coverage to allow the population to access mobile and Internet services and thus enable the digitalization of the population. Finally, this article shows the level of coverage, the digital divide and an overview of the deployment of base stations (BTS) throughout the country to promote the transformation and digital inclusion of services.

Divide and recombine approach for warranty database: estimating the reliability of an automobile component

The continuously updated database of failures and censored data of numerous products has become large, and on some covariates, information regarding the failure times is missing in the database. As the dataset is large and has missing information, the analysis tasks become complicated and a long time is required to execute the programming codes. In such situations, the divide and recombine (D&R) approach, which has a practical computational performance for big data analysis, can be applied. In this study, the D&R approach was applied to analyze the real field data of an automobile component with incomplete information on covariates using the Weibull regression model. Model parameters were estimated using the expectation maximization algorithm. The results of the data analysis and simulation demonstrated that the D&R approach is applicable for analyzing such datasets. Further, the percentiles and reliability functions of the distribution under different covariate conditions were estimated to evaluate the component performance of these covariates. The findings of this study have managerial implications regarding design decisions, safety, and reliability of automobile components.

Outlier-DivideConquer:近似聚集查询中离群分治取样算法

取样是一种通用有效的近似技术,利用取样技术进行近似聚集查询处理是决策支持系统和数据挖掘实现技术中的常用方法.如何正确有效地给出近似查询结果并最小化近似查询误差是近似查询处理的关键和目标.在深入研究近似聚集查询取样方法的基础上,本文提出了一个有误差确界且只需单遍扫描数据集的离群分治取样Outlier-DivideConquer算法,该算法在聚集属性内部存在高方差分布时能克服随机均匀取样局限,可显著降低近似查询误差,且执行效率优于同类算法.最后通过与传统均匀取样算法的实验比较验证了Outlier-DivideConquer算法的有效性和正确性.

基于归一分解的并行多目标Dividing Rectangles算法

多目标优化问题普遍存在且难以解决,目前多采用多目标进化算法进行求解.然而,这些方法通常在种群初始化阶段和进化过程中包含随机操作以保持多样性,导致了其结果不可复现且缺乏全局收敛的理论保证.鉴于此,提出了一种基于归一分解的多目标Dividing Rectangles(DIRECT)算法,首先通过一种可较好捕捉复杂前沿的归一分解方法将原问题分解为一系列子问题,以降低问题计算复杂度;其次,采用Dividing Rectangles算法同时优化分解得到的子问题,并在优化过程中基于全局关联机制将生成的候选解分配给相应的子问题,以更好地保留优秀候选解并提高算法搜索效率;最后,证明了算法的收敛性.此外,为了进一步提高计算效率,提出了一种基于自适应关联迁移策略的多层次多粒度并行方案,并基于该方案对所提出的算法进行了并行化.将所提算法应用于多个基准优化问题,实验结果表明,相比于NSGA-II,所提串行算法能够产生收敛性、多样性更为优越的帕累托最优解集,并行算法可在大规模缩短问题求解时间的同时,进一步提升帕累托前沿近似精度.

The Formation Logic of the Digital Divide and Feasible Ways to Cross It:An Access-Based Analysis

How enterprises overcome the digital divide in a digital economy is a topic related to efficiency and fairness.The formation of the digital divide has showcased a certain level of objectivity and is also influenced by the characteristics of enterprises themselves.Based on the model that expands the information and communication technology(ICT)access,concept,we explored the digital divide’s formation logic of the digital divide and feasible ways to cross it.Our findings shed light on its formation logic,which includes elements of the subjective will of enterprises to transform,the fear of transformation,the dependence on development paths,and the cost of using digital technology,all of which have contributed to disparities in enterprises’motivational access.In addition,differences in the construction of digital infrastructure,financial strengths,business models,and heterogeneity in cluster networks have led to differences in enterprises’material access.The absorptive capacity of enterprises has affected their skill access,while the management capability influences the application access of enterprises.We also found that crossing the digital divide requires the joint efforts of governments,markets,and enterprises in the four access dimensions.

Optimization of DC Resistance Divider Up to 1200 kV Using Thermal and Electric Field Analysis

Self-heating and electric field distribution are the primary factors affecting the accuracy of the Ultra High Voltage Direct Current(UHVDC)resistive divider.Reducing the internal temperature rise of the voltage divider caused by self-heating,reducing the maximum electric field strength of the voltage divider,and uniform electric field distribution can effectively improve the UHVDC resistive divider’s accuracy.In this paper,thermal analysis and electric field distribution optimization design of 1200 kV UHVDC resistive divider are carried out:(1)Using the proposed iterative algorithm,the heat dissipation and temperature distribution of the high voltage DC resistive divider are studied,and the influence of the ambient temperature and the power of the divider on the temperature of the insulating medium of the divider is analyzed;(2)Established the finite element models of 1200 kV and 2×600 kV DC resistive dividers,analyzed the influence of the size of the grading ring and the installation position on the maximum electric field strength of the voltage divider,and calculated the impact of the shielding resistor layer on the vicinity of the measuring resistor layer.The research indicates that:(1)The temperature of the insulating medium is linearly related to the horsepower of the voltage divider and the ambient temperature;(2)After the optimized design of the electric field,the maximum electric field strength of the 1200 kV DC resistive divider is reduced to 1471 V/mm,which is about 24% lower than that of the unoptimized design;(3)Installing the shielding resistor layer can significantly improve the electric field near the measuring resistor layer.This paper has an important reference function for improving the accuracy of the UHVDC resistive divider.

A Miniaturized Broadband Wilkinson Power Divider Using Micro-Strip Branch Lines

A miniaturized broadband Wilkinson power divider is proposed. Micro-strip branch lines are introduced to replace multiple resistors used in multi-stage Wilkinson power dividers to increase the bandwidth of single-stage Wilkinson power dividers. To demonstrate its performance, an improved single-stage Wilkinson power divider with four micro-strip branch lines was designed. Simulated results show that the insert loss is better than 3.2 dB, the input return loss, output return loss, and isolation are better than 15 dB respectively, across a 76% bandwidth from 18 to 40 GHz. .

Innovation in the Public Sector in the Start-up Nation:Challenges of Technology,Bureaucracy,and Digital Divide

Innovation provides opportunities to all countries,as advancement in technology and globalization of economic markets encourage global competition and increase the role of governments in gaining a strategic competitive advantage while boosting economic growth and productivity.According to the OECD,innovation can make a difference in addressing developmental challenges and providing catalyst for countries to accelerate business processes and practices that improve public service efficiency.The public sector plays a significant role in modern economies and innovation is a necessary condition for improving government services to the public and creating a competitive economy.Israel is known as the“start-up nation”,but innovation policies and strategies relating to the public sector are less developed than those of business innovation due to lack of innovation culture,digital divide,and bureaucracy.The research examines innovation in the public sector in Israel compared to other OECD countries.It is argued that despite the enormous influence of high-tech and start-ups on the economy and gross of national product,the flourishing technology sector has not contributed to other sectors of the economy and the performance of the public service lags behind the private sector in terms of innovation and efficiency.The research concludes that implementing Israel’s success in business innovation into the public sector requires long-run strategic investments and public policies to increase the supply and quality of human capital and infrastructure.The goal should be to narrow digital divide with other developed countries and advance the technological capabilities and productivity of the public service.

A Programmable 2.4GHz CMOS Multi-Modulus Frequency Divider

A programmable multi-modulus frequency divider is designed and implemented in a 0. 35μm CMOS process. The multi-modulus frequency divider is a single chip with two dividers in series,which are divided by 4 or 5 prescaler and by 128-255 multi-modulus frequency divider. In the circuit design, power and speed trade-offs are analyzed for the prescaler, and power optimization techniques are used according to the input frequency of each divider cell for the 128-255 multimodulus frequency divider. The chip is designed with ESD protected I/O PAD. The dividers chain can work as high as 2.4GHz with a single ended input signal and beyond 2.6GHz with differential input signals. The dual-modulus prescaler consumes 11mA of current while the 128-255 multi-modulus frequency divider consumes 17mA of current with a 3.3V power supply. The core area of the die without PAD is 0.65mm × 0.3mm. This programmable multi-modulus frequency divider can be used for 2.4GHz ISM band PLL-based frequency synthesizers. To our knowledge, this is the first reported multi-modulus frequency divider with this structure in China.

Integrated Low-Power CMOS VCO and Its Divide-by-2 Dividers

An integrated low power CMOS VCO and its divide by 2 dividers for WLAN transceivers are presented.The VCO is based on on chip symmetrical spiral inductor and differential diode and the divide by 2 dividers are based on the ILFD technique.Due to differential LC tanks and ILFD techniques,power consumption is low.The circuit is implemented in a 0 18μm CMOS process.Measurements show the proposed circuit could produce 3 6/1 8GHz dual band LO signals with a wide tuning range and low phase noise.1 8GHz LO signals are quadrature.It consumes 5mA at V DD =1 5V.The size of die area is only 1 0mm×1 0mm.

0.18μm CMOS programmable frequency divider design for DVB-T

The implementation of a programmable frequency divider, which is one of the components of the phase-locked loop （PLL） frequency synthesizer for digital video broadcastingterrestrial （DVB-T） and other modem communication systems, is presented. By cooperating with a dual-modulus prescaler, this divider can realize an integer frequency division from 926 to 1 387. Besides the traditional standard cell design flow, such as logic synthesis, placement and routing, the interactions between front-end and back-end are also considered to optimize the design flow under deep submicron technology. By back-annotating the back-end information to front-end design, a custom wire-load model is created which is more practical compared with the default model. This divider has been fabricated in TSMC 0. 18μm CMOS technology using Artisan standard cell library. The chip area is 675 μm × 475 μm and the power consumption is about 2 mW under a 1.8 V power supply. Measurement results show that it works correctly and can realize a frequency division with high precision.

An 8.5GHz 1∶8 Frequency Divider in 0.35μm CMOS Technology

An 1∶8 frequency divider is designed and realized in a 0 35μm standard CMOS technology.The chip consists of three stages of 1∶2 divider cells,which are constructed with source couple logic (SCL) flip flops.By revising the traditional topology of SCL flip flop,a divider with better performances is got.The results of measurement show that the whole chip achieves the frequency division at more than 8 5GHz.Each 1∶2 divider consumes about 11mW from a 3 3V supply.The divider can be used in RF and optic fiber transceivers and other high speed systems.

Bridging Digital Divide for English Learners at Chinese Secondary Schools

This article reviews the concept of digital divide and particularly discusses the digital divide among K-12 students in rural and urban China,as well as the e-learning strategies initiated by the Chinese government that were designed to minimize this digital divide in China.This article concludes by explaining the issue of skills on effective e-learning and correspondingly making suggestions for English teachers in K-12 schools in China.

The Art of Power Dividing:A Review for State-of-the-Art Planar Power Dividers

In this paper,massive state-of-theart planar power dividers are presented and discussed. The innovations of these superiorly-performanced power dividers lie in the performance breakthrough,physical configurations and function integrations. Eventually,based on the trend presented,the future of the power dividers is predicted. This paper might have inspiration significance to illuminate the way for the development of power dividers.

Design of a Frequency Divider with Reduced Complexity Based on a Resonant Tunneling Diode

A novel edge-triggered D-flip-flop based on a resonant tunneling diode （RTD） is proposed and used to construct a binary frequency divider. The design is discussed in detail and the performance of the circuit is verified using SPICE. Relying on the nonlinear characteristics of RTD,we reduced the number of components used in our DFF circuit to only half of that required using conventional CMOS SCFL technology.

Use of Topographic Map Evidence to Test a Recently Proposed Regional Geomorphology Paradigm: Wind River-Sweetwater River Drainage Divide Area, Central Wyoming, USA

Topographic map evidence from the Wyoming Wind River-Sweetwater River drainage divide area is used to test a recently proposed regional geomorphology paradigm defined by massive south- and southeast-oriented continental ice sheet melt water floods that flowed across the entire Missouri River drainage basin. The new paradigm forces recognition of an ice sheet created and occupied deep “hole” and is fundamentally different from the commonly accepted paradigm in which a pre-glacial north- and northeast-oriented slope would have prevented continental ice sheet melt water from reaching or crossing the Wind River-Sweetwater River drainage divide. Divide crossings (or low points) are identified as places where water once flowed across the drainage divide. Map evidence is interpreted first from the accepted paradigm perspective and second from the new paradigm perspective to determine the simplest explanation. Both paradigm perspectives suggest south-oriented water crossed the drainage divide, although accepted paradigm interpretations do not satisfactorily explain the large number of observed divide crossings and are complicated by the need to bury the Owl Creek and Bridger Mountains to explain why the Wind River now flows in a north direction through Wind River Canyon. New paradigm interpretations explain the large number of divide crossings as diverging and converging channel evidence (as in flood-formed anastomosing channel complexes), Owl Creek and Bridger Mountain uplift to have occurred as south-oriented floodwaters carved Wind River Canyon, and a major flood flow reversal (caused by ice sheet related crustal warping and the opening up of deep “hole” space by ice sheet melting) as being responsible for the Wind River abrupt turn to the north. While this test only addresses topographic map evidence, Occam’s Razor suggests the new paradigm offers what in science should be the preferred Wind River-Sweetwater River drainage divide origin interpretations.

A Low Power,High Sensitivity SiGe HBT Static Frequency Divider up to 90 GHz for Millimeter-Wave Application

A layout and connection optimization for static frequency divider is presented. The layout optimization provides a new circle topology transistors placement and reasonable connection structure, which reduces the parasitic effectively and enables self-oscillation frequency enhancement. Besides, bandwidth enhancement techniques based on a center-tap capacitor in input balun design and inductive peaking in latch design are adopted to improve further high frequency performance with low power consumption. As a proof of concept, design of a divide-by-2 static frequency divider in 0.13 μm SiGe BiCMOS technology is reported. With single-ended input clock signal, the divider is measured to be operated from 40 to 90 GHz. Phase noise measurements of a 90 GHz input clock signal indicate ideal behavior with no measurable noise contribution from the divider. The divider followed by a buffer that can deliver more than-10 dBm output power, which is sufficient to drive succeeding stage. To the author's knowledge, the divider exhibits a competitive power dissipation and the highest FOM among silicon based frequency dividers that operating higher than 70 GHz.

Numerical optimisation and experimental validation of divided rail freight brake disc crown

In this study, numerical optimisation and experimental validation of a divided rail freight brake disc crown made of grey cast iron EN-GJL-250 is presented.The analysed brake disc is used in rail freight wagons and possesses a load capacity of 22.5 tons per axle. Two of the divided rail freight brake discs are mounted on each axle.With the aid of numerical analysis, the thermal dissipation properties of the brake disc were optimised and ventilation losses were reduced, and the numerical results were compared with experimental results. A one-way fluid–structure interaction analysis was performed. A computational fluid dynamic model of a divided rail freight brake disc, used to predict air flow properties and heat convection, was incorporated into a finite element model of the disc and used to evaluate the temperature of the disc. A numerical parametrical optimisation of cooling ribs of the brake disc was also performed, and novel optimised cooling ribs were developed. A transient thermal numerical analysis of the brake disc was validated using temperature measurements obtained during a braking test on a test bench. The ventilation losses of the brake disc were measured on a test bench specifically designed for the task, and the losses were compared to the simulation results. The experimentally obtained ventilation losses and temperature measurements compared favourably with the simulation results, confirming that this type of simulation process may be confidently applied in the future. Through systematic optimisation of the divided rail freight brake disc, ventilation losses were reduced by 37% and the mass was reduced by 21%, resulting in better thermal performance that will bring with it substantial energy savings.

Origin of Little Missouri River - South Fork Grand River and nearby Drainage Divides in Harding County, South Dakota and Adjacent Eastern Montana, USA

Barbed tributaries flowing in southeast directions, an asymmetric drainage divide with both the South Fork Grand River and the North Fork Moreau River, and the Jump-off escarpment-surrounded basin (interpreted here to be a large abandoned headcut) are examples of topographic map evidence suggesting the north oriented Little Missouri River valley eroded headward across a large southeast oriented anastomosing complex of ice-marginal melt water flood flow channels that once crossed Harding County, South Dakota. Additional evidence includes southeast oriented tributaries to the northeast oriented South Fork Grand River and multiple divide crossings (e.g. through valleys and wind gaps) on the Boxelder Creek-Little Missouri River divide (in eastern Montana and west of the Little Missouri River) and suggests deep regional erosion occurred as the north oriented Little Missouri River valley eroded headward into and across the region. Harding County is located south and west of the southwest limit of coarse-grained glacial erratic material and ice-marginal melt water flow routes logically should have crossed it. Deep melt water erosion of Harding County and adjacent eastern Montana regions to the west is not consistent with many previous drainage history and glacial history interpretations, but is consistent with deep erosion by continental ice sheets.

Design of 0.18 μm CMOS programmable frequency divider based on standard cells

The design of a programmable frequency divider, which is one of the components of the phase-locked loop （PLL） frequency synthesizer for transmitter and receiver in IEEE 802. 11 a standard, is investigated. The main steps in very large-scale integration （VLSI） design flow such as logic synthesis, floorplan and placement ＆ routing （P ＆ R） are introduced. By back-annotating the back-end information to the front-end design, the custom wire-load model is created and used for optimizing the design flow under deep submicron technology. The programmable frequency divider is implemented based on Artisan TSMC （Taiwan Semicoductor Manufacturing Co. Ltd. ）0. 18μm CMOS （complementary metal-oxide-semiconductor） standard cells and fabricated. The Chip area is 1 360. 5μm^2 and can work in the range of 100 to 200 MHz. The measurement results indicate that the design conforms to the frequency division precision.