Condensation Heat Transfer on Geometrically Enhanced Horizontal Tube: A Review

In this chapter, an attempt has been made to present the recent state of knowledge of free‐convection condensation heat transfer on geometrically enhanced tubes. This survey is divided into three sections. The first section concentrates on research on condensate flooding or retention. The second and the third sections cover the experimental and the theoretical work on geometrically enhanced tubes, respectively

Separation Framework: An Enabler for Cooperative and D2D Communication for Future 5G Networks

Soaring capacity and coverage demands dictate that future cellular networks need to soon migrate towards ultra-dense networks. However, network densification comes with a host of challenges that include compromised energy efficiency, complex interference management, cumbersome mobility management, burdensome signaling overheads and higher backhaul costs. Interestingly, most of the problems, that beleaguer network densification, stem from legacy networks' one common feature i.e., tight coupling between the control and data planes regardless of their degree of heterogeneity and cell density. Consequently, in wake of 5G, control and data planes separation architecture (SARC) has recently been conceived as a promising paradigm that has potential to address most of aforementioned challenges. In this article, we review various proposals that have been presented in literature so far to enable SARC. More specifically, we analyze how and to what degree various SARC proposals address the four main challenges in network densification namely: energy efficiency, system level capacity maximization, interference management and mobility management. We then focus on two salient features of future cellular networks that have not yet been adapted in legacy networks at wide scale and thus remain a hallmark of 5G, i.e., coordinated multipoint (CoMP), and device-to-device (D2D) communications. After providing necessary background on CoMP and D2D, we analyze how SARC can particularly act as a major enabler for CoMP and D2D in context of 5G. This article thus serves as both a tutorial as well as an up to date survey on SARC, CoMP and D2D. Most importantly, the article provides an extensive outlook of challenges and opportunities that lie at the crossroads of these three mutually entangled emerging technologies.Comment: 28 pages, 11 figures, IEEE Communications Surveys & Tutorials 201

Spatial and Social Paradigms for Interference and Coverage Analysis in Underlay D2D Network

The homogeneous Poisson point process (PPP) is widely used to model spatial distribution of base stations and mobile terminals. The same process can be used to model underlay device-to-device (D2D) network, however, neglecting homophilic relation for D2D pairing presents underestimated system insights. In this paper, we model both spatial and social distributions of interfering D2D nodes as proximity based independently marked homogeneous Poisson point process. The proximity considers physical distance between D2D nodes whereas social relationship is modeled as Zipf based marks. We apply these two paradigms to analyze the effect of interference on coverage probability of distance-proportional power-controlled cellular user. Effectively, we apply two type of functional mappings (physical distance, social marks) to Laplace functional of PPP. The resulting coverage probability has no closed-form expression, however for a subset of social marks, the mark summation converges to digamma and polygamma functions. This subset constitutes the upper and lower bounds on coverage probability. We present numerical evaluation of these bounds on coverage probability by varying number of different parameters. The results show that by imparting simple power control on cellular user, ultra-dense underlay D2D network can be realized without compromising the coverage probability of cellular user.Comment: 10 pages, 10 figure

Intracell interference characterization and cluster interference for D2D communication

The homogeneous spatial Poisson point process (SPPP) is widely used for spatial modeling of mobile terminals (MTs). This process is characterized by a homogeneous distribution, complete spatial independence, and constant intensity measure. However, it is intuitive to understand that the locations of MTs are neither homogeneous, due to inhomogeneous terrain, nor independent, due to homophilic relations. Moreover, the intensity is not constant due to mobility. Therefore, assuming an SPPP for spatial modeling is too simplistic, especially for modeling realistic emerging device-centric frameworks such as device-to-device (D2D) communication. In this paper, assuming inhomogeneity, positive spatial correlation, and random intensity measure, we propose a doubly stochastic Poisson process, a generalization of the homogeneous SPPP, to model D2D communication. To this end, we assume a permanental Cox process (PCP) and propose a novel Euler-Characteristic-based approach to approximate the nearest-neighbor distribution function. We also propose a threshold and spatial distances from an excursion set of a chi-square random field as interference control parameters for different cluster sizes. The spatial distance of the clusters is incorporated into a Laplace functional of a PCP to analyze the average coverage probability of a cellular user. A closed-form approximation of the spatial summary statistics is in good agreement with empirical results, and its comparison with an SPPP authenticates the correlation modeling of D2D nodes

Solutions for the Power Distribution System of Karachi Electric (K- Electric) to Prevent Deaths in Rainy Season

Karachi is the metropolitan city of Pakistan. In rainy or flood season many deaths occurred due to electric shock. For the prevention, we suggest here to K-Electric (Karachi Electric Supply Distribution company) to control death casualties due to electric shock in rainy season. In suggestion paper providing some suggestions to the big power supplier of Karachi (K-Electric) about safety, maintenance, and monitoring for the prevention from deaths occur in metropolitan city due to electric shock. Those deaths occur due to faults in electric pole and touch the fallen live wire. When people touch the pole, they got electric shock in rainy and storm condition due to these electric faults occur in this condition provides enough loss to humans in the form to lose their lives. For the prevention or overcome the loss of life and danger here are giving some suggestions, if do work on following safety, maintenance and monitoring system then get the control on that loss will occur in heavy rain or flood

LTE-advanced self-organizing network conflicts and coordination algorithms

Self-organizing network (SON) functions have been introduced in the LTE and LTEAdvanced standards by the Third Generation Partnership Project as an excellent solution that promises enormous improvements in network performance. However, the most challenging issue in implementing SON functions in reality is the identification of the best possible interactions among simultaneously operating and even conflicting SON functions in order to guarantee robust, stable, and desired network operation. In this direction, the first step is the comprehensive modeling of various types of conflicts among SON functions, not only to acquire a detailed view of the problem, but also to pave the way for designing appropriate Self-Coordination mechanisms among SON functions. In this article we present a comprehensive classification of SON function conflicts, which leads the way for designing suitable conflict resolution solutions among SON functions and implementing SON in reality. Identifying conflicting and interfering relations among autonomous network management functionalities is a tremendously complex task. We demonstrate how analysis of fundamental trade-offs among performance metrics can us to the identification of potential conflicts. Moreover, we present analytical models of these conflicts using reference signal received power plots in multi-cell environments, which help to dig into the complex relations among SON functions. We identify potential chain reactions among SON function conflicts that can affect the concurrent operation of multiple SON functions in reality. Finally, we propose a selfcoordination framework for conflict resolution among multiple SON functions in LTE/LTEAdvanced networks, while highlighting a number of future research challenges for conflict-free operation of SON

Why not everybody loves Hofstede? What are the alternative approaches to study of culture?

In these days the Hofstede's work on culture is most quoted in many publications. For scholars and practitioners knowing and having complete understanding of cross cultural dimensions, Hofstede's work plays an important and dynamic role. His observations and analysis gives the full understanding to the readers and as well as authors and scholars. Still such pioneering work faces much criticism by scholars. Some of the scholars appreciated his credible work. Some scholars quote his finding in their research and some ignore it. In our paper, this study concludes all the criticism on hofstede's work. Basically there are two parts of this paper; in first part we discuss the reason why hofstede's work faces criticism and in second part we recommend various other cultural dimensions, which we can use to understand the culture. Research Findings This paper tries to conclude all the dimensions and also suggest the model for understanding the national culture. Key Words Culture, National culture, Hofstede, cross cultural dimension

Helping students to get better grades in mathematics at the elementary level

The current study is conducted to explore the learning potential of students at the elementary level by using the scaffolding technique. The study aimed to measure the efficiency of the scaffolding teaching method provided to the students at the elementary level. As it was an experimental study, so, no population was defined. The sample was selected from Gov. Girls Higher Secondary SchoolModel Town A, Bahawalpur, Punjab, Pakistan. All 6th classes of this school were included to analyze the effect of scaffolding as an intervention. Retention of learning after 3 months, the provision of scaffolding in comparison to the traditional method was assessed. After the posttest, there was a retention test as the final test from all four groups. Solomon's four-group design was used for this experiment in which there were 40 students in each group and 160 total participants. In the current study, Pretest, posttest, and after 3months retention test was conducted as research tools. To analyze the data, SPSS version 20 one-sample t-test were used to analyze the data. The Data revealed that scaffolding was proved to be a better strategy compared to the control group. Even the results of retention of learning skills were higher than the control group. Students showed good understanding, remembering, and better-solving processes in experimental groups. Study recommended that scaffolding teaching needs a highly structured supervised environment and may be conducted in controlled conditions. It is recommended that in teacher education, the prospective teachers may be prepared in the principles, procedures, and rules of scaffolding. A due consideration may be given to teaching strategies in all teacher education programs in the country as it is an innovative and progressive way of teaching

Effect of Condensate Flow Rate on Retention Angle on Horizontal Low-Finned Tubes

This article is in an Open Access journalThe paper reports experimental results using simulated condensation on eight horizontal integral finned tubes with different fin spacing but same root diameter. Condensation was simulated with low approaching zero vapor velocity of condensate using three liquids (water, ethylene glycol and R141b) supplied to the tube via small holes between the fins along the top of the tubes. Controlling parameters of the investigation were fin spacing of condensation tubes, flow rate of condensate and surface tension to density ratio of the condensate. The results indicate that the retention angle (measured from the top of the tube to the position where the inter-fin space is completely filled with liquid) increases with the increase in fin spacing. Also, retention angle increases as the density of the condensate increases but retention angle decreases with increase in surface tension. Interesting finding is seen as retention angle remains constant with increase in condensate flow rate, starting from very low (nearly zero) flow rate to the flow rate at which the tube gets fully flooded. The critical flow rate for eight tubes of defined fin density against three working fluids is measured. Results obtained from simulated condensation for almost zero condensate velocity are in good agreement with earlier data and theoretical model for retention angle on such tubes

Heat Transfer Applications of TiO2 Nanofluids

To achieve acme heat transfer is our main disquiet in many heat transfer applications such as radiators, heat sinks and heat exchangers. Due to furtherance in technology, requirement for efficient systems have increased. Usually cooling medium used in these applications is liquid which carries away heat from system. Liquids have poor thermal conductivity as compared to solids. In order to improve the efficiency of system, cooling medium with high thermal conductivity should be used. Quest to improve thermal conductivity leads to usage of different methods, and one of them is addition of nanoparticles to base liquid. Application of nanofluids (a mixture of nanoparticles and base fluid) showed enhancement in heat transfer rate, which is not possible to achieve by using simple liquids. Different researchers used TiO2 nanoparticles in different heat transfer applications to observe the effects. Addition of titanium oxide nanoparticles into base fluid showed improvement in the thermal conductivity of fluid. This chapter will give an overview of usage of titanium oxide nanoparticles in numerous heat transfer applications