Beyond 5G Networks: Integration of Communication, Computing, Caching, and Control

In recent years,the exponential proliferation of smart devices with their intelligent applications poses severe challenges on conventional cellular networks.Such challenges can be potentially overcome by integrating communication,computing,caching,and control(i4C)technologies.In this survey,we first give a snapshot of different aspects of the i4C,comprising background,motivation,leading technological enablers,potential applications,and use cases.Next,we describe different models of communication,computing,caching,and control(4C)to lay the foundation of the integration approach.We review current stateof-the-art research efforts related to the i4C,focusing on recent trends of both conventional and artificial intelligence(AI)-based integration approaches.We also highlight the need for intelligence in resources integration.Then,we discuss the integration of sensing and communication(ISAC)and classify the integration approaches into various classes.Finally,we propose open challenges and present future research directions for beyond 5G networks,such as 6G.

Performance Analysis of Cooperative NOMA with Energy Harvesting in Multi-Cell Networks

In this paper,an energy harvesting enabled cooperative non-orthogonal multiple access(NOMA)system for a multi-cell network is investigated.Particularly,during the direct transmission phase,base stations send their superposed messages to the near users and far users simultaneously according to a NOMA principle,while the near users act as energy harvesting enabled relays employing a power splitting protocol.During the cooperative phase,the near users transmit their decoded messages to the corresponding far users using harvested energy.Using tools from stochastic geometry,we firstly calculate the signal to interference ratios of the users in each NOMA group including one near user and one far user.Then,the closed-form expressions of the coverage probability,ergodic rate,and energy efficiency are derived respectively.Numerical results validate the derived expressions and show that the energy harvesting enabled cooperative NOMA system in a multi-cell network can improve the coverage probability,ergodic rate,and energy efficiency compared to its counterpart OMA system.

Joint Resource Allocation and Coordinated Computation Offloading for Fog Radio Access Networks

The cloud radio access network(C-RAN) and the fog computing have been recently proposed to tackle the dramatically increasing traffic demands and to provide better quality of service(QoS) to user equipment(UE).Considering the better computation capability of the cloud RAN(10 times larger than that of the fog RAN) and the lower transmission delay of the fog computing,we propose a joint resource allocation and coordinated computation offloading algorithm for the fog RAN(F-RAN),which takes the advantage of C-RAN and fog computing.Specifically,the F-RAN splits a computation task into the fog computing part and the cloud computing part.Based on the constraints of maximum transmission delay tolerance,fronthaul and backhaul capacity limits,we minimize the energy cost and obtain optimal computational resource allocation for multiple UE,transmission power allocation of each UE and the event splitting factor.Numerical results have been proposed with the comparison of existing methods.

Radio Access Network Slicing Based on C/U Plane Separation

Network slicing achieves many interests from industry and academics due to its flexibility and scalability.In this paper,we present a novel slicing scheme for radio access networks(RANs) based on control/user(C/U) plane separation.Firstly,we divide e NBs into two sub-e NBs called Ce NB and Ue NB,for transmitting control data and user data respectively,thereby facilitating C/U plane separation.Secondly,upon Ce NBs and Ue NBs being virtualized,we develop two RAN slices for control and user plane respectively.Experimental results show the feasibility of the proposed scheme.

Enhanced PSO Based Energy-Efficient Resource Allocation and CQI Based MCS Selection in LTE-A Heterogeneous System

In order to maximize system energy efficiency(EE) under user quality of service(Qo S) restraints in Long Term Evolution-Advanced(LTE-A) networks,a constrained joint resource optimization allocation scheme is presented,which is NP-hard. Hence,we divide it into three sub-problems to reduce computation complexity,i.e.,the resource block(RB) allocation,the power distribution,and the modulation and coding scheme(MCS) assignment for user codewords. Then an enhanced heuristic approach GAPSO is proposed and is adopted in the RB and power allocation respectively to reduce computational complexity further on. Moreover,a novel MCS allocation scheme is put forward,which could make a good balance between the system reliability and availability under different channel conditions. Simulation results show that the proposed GAPSO could achieve better performance in convergence speed and global optimum searching,and that the joint resource allocation scheme could improve energy efficiency effectively under user Qo S requirements.

Power Allocation for Wireless Powered MIMO Transmissions with Non-Linear RF Energy Conversion Models

We study a radio frequency(RF) wireless energy transfer(WET) enabled multiple input multiple output(MIMO) system. A time slotted transmission pattern is considered. Each slot can be divided into two phases, downlink(DL) WET and uplink(UL) wireless information transmission(WIT). Since energy conversion efficiency of the energy harvesting circuits are non.linear, the conventional linear model leads to a mismatch for resource allocation. In this paper, the power allocation algorithm considering the practical non.linear energy harvesting circuits is studied. The optimization problem is formulated to maximize the energy efficiency of system with multiple constraints, i.e., the transmission power, the received power and the minimum harvested energy, which is a non.convex problem. We transform the objective function from fractional form into an equivalent objective function in subtractive form and provide an iterative power allocation algorithm to achieve the optimal solution. Numerical results show that our proposed algorithm with the non.linear RF energy conversion models can achieve much better performance than the algorithm with the conventional linear model.

5G ENTERING INTO A NEW ERA

The ever increasing wireless data services, such asimaging, video, audio, multimedia, etc., have de-mands for the very high speed wireless communicationsand network, which are unfortunately a bottleneck whencombining with the wireline core network. Users＇ arenow expecting high quality of experience with low-costdevices, ubiquitous connectivity, energy efficiency, highreliability, or even ultra-low latency if a vehicle terminalis applied.

Role of integrin β1 in sensitivity to chemotherapy of pulmonary adenocarcinoma A549

Objective:The aim of our study was to investigate the effect of integrin β1 on influencing the sensitivity to chemotherapy of human pulmonary adenocarcinoma A549 cells.Methods:Human pulmonary adenocarcinoma A549 multicellular spheroids(MCS) were constructed with three dimensional cell culture methods.Cell counting using blood cell counter was employed to detect the sensitivity to ADM of A549 MCS before and after blocking integrin β1;integrin β1 expression of A549 MCS and cell apoptosis was detected by flow cytometry.Results:A549 MCS were successfully established.The integrin β1 expression of A549 MCS elevated with the concentration of ADM(< 0.02 μg/mL).Blocking of integrin β1 lead to higher sensitivity to ADM,and IC50 decreased from 0.19 μg/mL to 0.11 μg/mL,and apoptosis rate increased from(15.81 ± 1.87)% to(30.14 ± 2.89)%.Conclusion:The cell adhesion molecules integrin β1 could influence the sensitivity to chemotherapy of A549 MCS and inhibiting of cell apoptosis might be its mechanism.

An Energy-Efficient MAC Protocol for WSNs: Game-Theoretic Constraint Optimization with Multiple Objectives

In WSNs, energy conservation is the primary goal, while throughput and delay are less important. This re-sults in a tradeoff between performance (e.g., throughput, delay, jitter, and packet-loss-rate) and energy con-sumption. In this paper, the problem of energy-efficient MAC protocols in WSNs is modeled as a game-theoretic constraint optimization with multiple objectives. After introducing incompletely cooperative game theory, based on the estimated game state (e.g., the number of competing nodes), each node independ-ently implements the optimal equilibrium strategy under the given constraints (e.g., the used energy and QoS requirements). Moreover, a simplified game-theoretic constraint optimization scheme (G-ConOpt) is pre-sented in this paper, which is easy to be implemented in current WSNs. Simulation results show that G-ConOpt can increase system performance while still maintaining reasonable energy consumption.

Wormholing Influenced by Injection Temperature in Carbonate Rocks

This paper presented empirical models of describing reaction rate vs. hydrochloric acid temperature and concentration by regressing experimental data. And this paper also introduced the dependent reaction heat model into the thermal non-equilibrium models and coupled with two-scale continuum model to obtain governing equations for describing wormholing under non-isothermal conditions. The governing equations were discretized by implicit difference method and solved by programing. The effects of temperature on wormholing have been investigated based on the simulation results on 2-D vision. A significant difference of the effluent temperature between the dependent reaction heat model in present work and the constant reaction heat model in available literatures was observed, especially in high injection rate and strong acid concentration. In addition, the tendencies of optimum injection capacity vs. injection temperature under isothermal and non-isothermal conditions were almost different. Finally, an optimum injection temperature was found by changing the injection temperature under non-isothermal conditions.

High-throughput synthesis of size-controlled Pt-based catalysts

Pt catalysts are commonly used for chemical reaction processes due to its high catalytic activity and selectivity.Notably,the size of metal particles often has a significant impact on the performance of the metal-loaded catalysts.Therefore,developing highly efficiently synthesis method for the size control of Pt catalysts has great development prospects and research value.In this study,high-throughput size tuning of Pt-based catalysts was achieved by carbonizing the carriers.The experimental and characterization results showed that the size of the loaded Pt nanoparticles varied with different concentrations of glucose solution during carriers carbonization process.The reduction of 4-nitrophenol as a template reaction indicated that the reaction rate constant of the catalyst is approximately linear with the size of Pt particles.Importantly,a laboratory-built high-throughput synthesis system was applied for the catalyst synthesis,which enhances the automation of the laboratory exploratory experiments and makes it possible to synthesize catalysts with controllable size in batches.

Observation of mega-dune evaporation after various rain events in the hinterland of Badain Jaran Desert, China

The formation mechanisms of the mega-dunes and lakes in the hinterland of Badain Jaran Desert,China,is the focus of extensive academic research in the field of geoscience,and an often debated topic is whether atmospheric precipitation on the mega-dune can infiltrate to recharge groundwater.In the present study,the probability distribution functions and the return period analysis of extreme daily precipitation based on long-term precipitation records for the southern margin of Badain Jaran Desert and 2-year observation of hinterland precipitation were used to classify precipitation in the desert region.The data of automatic weather station and eddy covariance system in the desert hinterland were used to analyze evaporation on the mega-dune surface after various rain events.The results showed that the rain events in the desert could be divided into three categories.The first is conventional precipitation(CP),which is below 5 mm,accounting for roughly 90%of all rain events in the desert.The second and third categories are ordinary annual maximum(OAM)and extreme precipitation(EP),in which precipitation is roughly 20 mm and more than 40 mm,respectively.The atmospheric precipitation of CP and OAM evaporated from the megadune surface in 1–3 days and 3–4 weeks,respectively.Following an EP event,the mega-dune evaporation was negatively influenced by the upper dry sand layer,and a lengthy period was required for its complete removal.The accumulative evaporation and accumulative precipitation of all three types of rain events indicated that local atmospheric precipitation had no significant contribution to recharging the groundwater system in the hinterland of Badain Jaran Desert.This research will benefit comprehensive elucidation of the formation mechanism of lakes in the hinterland of Badain Jaran Desert.

Hydrochemical characteristics and recharge sources of Lake Nuoertu in the Badain Jaran Desert

We present a case study of physical and chemical indicators and isotope characteristics of Lake Nuoertu,one of the largest and deepest lakes of the Badain Jaran Desert.We analyze the concentrations of eight ions,total dissolved solids,and stable isotope composition of the lake and groundwater,as well as radioactive isotope tritium concentration in groundwater.The results show that annual and seasonal variations of the physical and chemical characteristics of Lake Nuoertu water are significantly greater than those of groundwater.The lake is uniformly mixed in the horizontal and vertical directions,and the hydrochemical types of the lake at different depths are consistent for Na–Cl–CO3–(SO4).Stable isotope composition of the lake and groundwater at Nuoertu is distributed along the local evaporation line(EL)slope,which is less than the slope of the global meteoric water line.The comparatively small slope shows the characteristic strong evaporation in the study area.Lake water isotopes are mostly in the upper right corner of the EL,whereas groundwater is mostly in the lower left corner.The main recharge source of Nuoertu lake water is groundwater,in combination with lake water and groundwater level change.The age of tufa springs around Nuoertu is about75–80 a,which shows that the initial recharge source of the lake is a mix between modern and 1952 or older;however,further research is required.

Biological fate and interaction with cytochromes P450 of the nanocarrier material,D-α-tocopheryl polyethylene glycol 1000 succinate

D-a-Tocopheryl polyethylene glycol 1000 succinate(TPGS,also known as vitamin E-TPGS)is a biodegradable amphiphilic polymer prepared by esterification of vitamin E with polyethylene glycol(PEG)1000.It is approved by the US Food and Drug Administration(FDA)and has found wide application in nanocarrier drug delivery systems(NDDS).Fully characterizing the in vivo fate and pharmacokinetic behavior of TPGS is important to promote the further development of TPGS-based NDDS.However,to date,a bioassay for the simultaneous quantitation of TPGS and its metabolite,PEG1000,has not been reported.In the present study,we developed such an innovative bioassay and used it to investigate the pharmacokinetics,tissue distribution and excretion of TPGS and PEG1000 in rat after oral and intravenous dosing.In addition,we evaluated the interaction of TPGS with cytochromes P450(CYP450s)in human liver microsomes.The results show that TPGS is poorly absorbed after oral administration with very low bioavailability and that,after intravenous administration,TPGS and PEG1000 are mainly distributed to the spleen,liver,lung and kidney before both being slowly eliminated in urine and feces as PEG1000.In vitro studies show the inhibition of human CYP450 enzymes by TPGS is limited to a weak inhibition of CYP3A4.Overall,our results provide a clear picture of the in vivo fate of TPGS which will be useful in evaluating the safety of TPGS-based NDDS in clinical use and in promoting their further development.

Experimental study on influencing factors of acid-fracturing effect for carbonate reservoirs

Acid fracturing treatment is the key technique for stimulation and stable production in carbonate reservoirs.In order to improve the carbonate reservoirs acid fracturing effect,in this paper,with a large number of experiments as the main research methods,study on influencing factors of acidfracturing effect for carbonate reservoirs from increase the effective distance of living acid,increase acid corrosion eched fracture conductivity,reduce the acid fluid loss,etc.The effective distances of live acid calculated with reacted acid limitations measured in different acid systems are quite different from those calculated according to previous standard.Fracture conductivity is one of the key parameters that affects acid fracturing effects,but it's difficult to be predicted accurately due to the strong randomness of acid-rock reaction as well as various influence factors.Analyses of the impacts on fracture conductivity resulted from the rock embedment intensity,closure stress,acid dosage,rock-acid contact time,acid fluid loss,acid pumping rate through self-developed small-core fracture capacity test instrument.Fluid loss during acid fracture can be well controlled by thickened liquid as well as solid particles,but formation damage occurs inevitably.Foamed acid is a specific fluid with high viscosity,low fluid loss,small friction resistance,good retarding property,strong fracture making ability,easy flowback and low damage,which is an ideal acid system for low pressure and low permeability carbonate reservoirs.In this paper,the theoretical study on percolation mechanism and fluid-loss control mechanism of foam(acid)in porous medium are presented with the help of visual microscopic model fluid drive unit.

Feasibility study on application of volume acid fracturing technology to tight gas carbonate reservoir development

How to effectively develop tight-gas carbonate reservoir and achieve high recovery is always a problem for the oil and gas industry.To solve this problem,domestic petroleum engineers use the combination of the successful experiences of North American shale gas pools development by stimulated reservoir volume(SRV)fracturing with the research achievements of Chinese tight gas development by acid fracturing to propose volume acid fracturing technology for fractured tightgas carbonate reservoir,which has achieved a good stimulation effect in the pilot tests.To determine what reservoir conditions are suitable to carry out volume acid fracturing,this paper firstly introduces volume acid fracturing technology by giving the stimulation mechanism and technical ideas,and initially analyzes the feasibility by the comparison of reservoir characteristics of shale gas with tight-gas carbonate.Then,this paper analyzes the validity and limitation of the volume acid fracturing technology via the analyses of control conditions for volume acid fracturing in reservoir fracturing performance,natural fracture,horizontal principal stress difference,orientation of insitu stress and natural fracture,and gives the solution for the limitation.The study results show that the volume acid fracturing process can be used to greatly improve the flow environment of tight-gas carbonate reservoir and increase production;the incremental or stimulation response is closely related with reservoir fracturing performance,the degree of development of natural fracture,the small intersection angle between hydraulic fracture and natural fracture,the large horizontal principal stress difference is easy to form a narrow fracture zone,and it is disadvantageous to create fracture network,but the degradable fiber diversion technology may largely weaken the disadvantage.The practices indicate that the application of volume acid fracturing process to the tight-gas carbonate reservoir development is feasible in the Ordovician Majiagou Formation of lower Paleozoic,which is of great significance and practical value for domestic tight-gas carbonate reservoir development and studies in the future.

Technical status and challenges of shale gas development in Sichuan Basin,China

During the past decade,shale gas developments have changed the energy structure in the US natural gas industry,and the exploration activities for shale gas are also increasing worldwide.According to the papers published in recent years,shale gas resources are quite abundant in China.With the successful experience obtained from North America,many state-of-the-art technologies are brought in and refined for field application.State-owned enterprise,private enterprises and foreign enterprises have all actively participated in the exploitation of shale gas.Compared with US,China faces many more challenges,both geological and above-ground,in the development of shale gas resources.This paper begins with the introduction of shale gas reserve distribution in China and the identified shale gas formation in Sichuan Basin.The following paper reviews the methodology employed in the geophysical prospecting,drilling and completion,and hydraulic fracturing process.Since China is in the early stage of shale gas development,there is a great technical gap between China and North America.Based on literature review,the major challenges faced in the exploration and production process are identified.What presented in this paper should be of particular interest to the personnels involved in shale gas production in China and countries that are about to set foot in shale gas business.It will also be of interest to researchers who are dedicated to developing these technologies to unlock unconventional gas resources in China.

General criterion for intersection between hydraulic induced fractures and pre-existing natural fractures

Pre-existing natural fractures and other structurally weak planes are usually well-developed in unconventional reservoirs.When such fractures intersect with hydraulic induced fractures,they will redirect and propagate as an important mechanical principle of volume fracturing by the formation of complex fracture networks.Under the shadow effect of natural fractures and other structurally weak planes with hydraulic supported fracture stress,hydraulic fractures do not fully propagate in the direction of the maximum horizontal-principal-stress.This paper computed the stress intensity factors of hydraulic fracture types I and II by integrating the various interactions,established universally-applicable mechanical principles for the propagation behavior when a hydraulic fracture propagating in an arbitrary direction intersects with a natural fracture at an arbitrary angle,and demonstrated the mechanical principles of the intersection between hydraulic induced fractures and pre-existing natural fractures.This study proved the following conclusions:as the intersection angle between the hydraulic fracture and the maximum horizontal-principal-stress increased,the possibility of the hydraulic fracture being captured by the natural fracture with an identical approaching angle first increased and then decreased;as the net stress increased,the intersection behavior between the hydraulic fracture and the natural fracture transitioned from penetration to capture.

Study and application of a new blockage remover in polymer injection wells

With the extensive application of polymer flooding technology in offshore oilfields,the plugging in polymer injection wells has become more and more severe,which seriously affects the oil displacement effect and regular production of oilfields.In this paper,a new kind of blockage remover has been developed and evaluated by rheological behavior experiments,dissolution experiments and core flooding experiments.The results reveal that this new blockage remover can effectively reduce the viscosity of polymer and completely degrade the reservoir blockage with low corrosion rate.It is beneficial to long-term production of oil wells in offshore oilfield.Results of core flooding experiments show that this new blockage remover can relieve polymer damage and improve permeability.The agent has been applied in LD10-1 oilfield in 2016,the daily injection rate increased significantly after stimulation.

Investigation of the degradation and stability of acrylamide-based polymers in acid solution: Functional monomer modified polyacrylamide

Acrylamide copolymers are often used as acidizing diverting and thickening agents for their advantageous thickening,flocculation,adhesion and resistance reduction properties.Experimental results indicate that the acid concentration greatly affects the properties of acrylamide polymers,which varies from results reported by other researchers.Considering the theoretical and field application value of the present study,four comparable acrylamide-based polymers were synthesized,and their macro-and micro-changes as well as the related changes in viscosity and molecular weight were studied in high-concentration hydrochloric acid.A proposed mechanism of acrylamide copolymer stability and degradation is provided,and further suggestions are made for the modification of acrylamide copolymers.