Load Reduction Rate Research Articles

Sudden Variation Effect of Aerodynamic Loads and Safety Analysis of Running Trains When Entering Tunnel Under Crosswind

Sudden variation of aerodynamic loads is a potential source of safety accidents of high-speed trains (HSTs). As a follow-up investigation on the aerodynamic response of a HST that enters a tunnel under crosswind environment, this paper focuses on the transient response of a HST’s safety indices based on the train–track coupling interaction model. Firstly, a wind–train–track coupling dynamic model is proposed by introducing transient aerodynamic loads into the vehicle–track system. Secondly, the temporal evolution of safety coefficients indicates that the train’s safety risk increases during tunnel entry with crosswind. Results show that the derailment coefficients and wheel load reduction rate during tunnel entry are not only larger than those in open air, but also those inside the tunnel are due to the sudden disappearance of wind excitation at the tunnel entrance. In addition, the characteristic wind curve, which is the wind velocity against the train speed, is presented for application based on the current specification of the safety criteria threshold. The investigation will be useful in assessing the safety risk of a running train subjected to other aerodynamic attacks, such as the coupling effect of an infrastructure scenario and crosswind in a windy area.

Evaluation of in-vivo anti-Salmonella activity of Uvaria chamae, Lantana camara and Phyllantus amarus used in Benin, West Africa

BackgroundUvaria chamae (Annonaceae), Phyllantus amarus (Phyllantaceae) and Lantana camara (Verbenaceae) are empirically alleged to be used as Beninese medicinal plants in the treatment of salmonellosis. This study aimed to produce scientific data on in vitro and in vivo efficacy of Uvaria chamae, Lantana camara and Phyllantus amarus on multiresistant Salmonella spp isolated in Benin.ResultsAfter performing in vitro tests on aqueous and ethanolic extracts of these plants, only the aqueous extract of Uvaria chamae (leaves) showed the best anti-Salmonella’s activity and was used for this in vivo experiment. The induction of salmonellosis revealed 9 × 108 CFU/ml was the optimal concentration triggering and maintaining symptoms in chicks. This infective concentration was used for in vivo assessment. Twenty-four hours post inoculation, the symptoms of salmonellosis (wet cloaca, diarrhea stools and somnolence) were observed in infected groups. After 7 days of treatment, the reduction of bacterial load at 100 mg/L, 200 mg/L, 400 mg/L of the extract was respectively 85%, 52.38% and 98% for Uvaria chamae, Phyllantus amarus and Lantana camara in the chick’s groups infected with Salmonella Typhimurium ATCC 14028. On the other hand, colistin completely cancelled the bacterial load (reduction rate of 100%).With the groups infected with Salmonella spp (virulent strain), the reduction rate of bacterial load at 100 mg/L, 200 mg/L, 400 mg/L of extract was 0%, 98.66%, and 99.33%. The extracts at 200 and 400 mg/L were more active than colistin, which reduced the bacterial load by 33.33%.The toxicity tests did not show any negative effect of Colistin and the Uvaria chamae’s extract on the biochemical and hematological parameters of the chicks.ConclusionThe aqueous extract of Uvaria chamae is active in vitro and in vivo on multiresistant strains of Salmonella enterica. This plant is a good candidate for the development of an improved traditional medicine for the management of salmonellosis.

Hydrologic-environmental effects of sponge city under different spatial scales

Abstract The storm water management models were established at three spatial scales (large, medium, and small) based on a sponge city pilot area in China to explore the hydrological and environmental effects of rainfall conditions and development modes. Results showed the following. (1) Total runoff reduction rates increased from 26.7% to 53.9% for the rainfall event of a 2-year recurrence period as the scale increased. For 5-year and above recurrence periods, total runoff reduction rates were 19.5–49.4%. These rates increased from the small to medium scale and slightly decreased from the medium to large scale. (2) The runoff coefficients were 0.87–0.29, which decreased from the small to medium scale and were basically constant from the medium to large scale. (3) The peak flow reduction rates decreased with increased recurrence periods. The rates increased initially and then decreased at the small scale, whereas the opposite trend occurred at the medium scale. (4) The reduction rates of pollutants were negatively correlated with recurrence periods under the three spatial scales. The pollution load reduction rates were 19.5–54.7%, which increased from the small to medium scale and were basically constant from the medium to large scale.

Research on dynamic performance and influence of new mesh-hole elastic pads for railway fasteners in an extremely cold environment

In order to research the dynamic properties of elastic pads for a new pattern mesh-hole in an extremely cold environment, a three-dimensional finite element model of a mesh-hole rail pad is established. The Mooney-Rivlin constitutive model is used to simulate the mechanical properties of rubber materials at different temperatures, and the temperature-dependent characteristics of dynamic stiffness and damping coefficients of the mesh-hole rail pads are analyzed. Based on the vehicle-track coupling dynamic theory, the driving safety and stability properties of the rail pads at extremely cold climate are calculated and analyzed, and the applicability of the mesh-hole rail pads in the extremely cold environment is further evaluated. The research conclusions are as follows. The mesh-hole rail pads have significant low-temperature sensitivity. Namely, above −10°C, the dynamic stiffness and damping coefficients of rail pads are stable, while below this temperature, the dynamic stiffness and damping coefficients of elastic pads increase rapidly. The mesh-hole rail pad has an obvious influence on the dynamic performance of a vehicle-track system when the temperature changes. Namely, the wheel-rail force and wheel load reduction rate increase rapidly with the decrease in temperature, while the vertical dynamic displacement of the rail decreases. Under the extremely cold climate, the wheel load reduction rate of a high-speed passenger vehicle increases sharply, so the method for reducing train speed should be adopted to ensure the safety of train operation.

Numerical analysis on the load reduction of a pipe-embedded window with different water temperatures and structures under different climates

Pipe-embedded windows can significantly reduce the cooling/heating load of buildings when integrated with low-grade energy. However, the studies on the load reduction effect under different climates remain insufficient, and the optimal location of double-glazing glass and the width of the air interlayer have not been studied. Thus, in this study, the performance of a pipe-embedded window with different water temperatures under different representative climates and structures is investigated numerically. According to the simulation, a linear relationship is found between the load and the climatic parameters with the specific structure of the pipe-embedded window, and the water temperature has a greater effect on the load than the outdoor air temperature. For three typical weather conditions from cold to hot environments (summer: 26 °C, 200 W/m2; 30 °C, 400 W/m2; 34 °C, 600 W/m2; winter: –25 °C; –10 °C; 5 °C), the limits of water temperature under a 25% load reduction rate are 27.7 °C, 39.8 °C, and 51.8 °C for summer and 8.4 °C, 12.0 °C, and 15.6 °C for winter, respectively. Internal thermal insulation is recommended for a pipe-embedded window, and the air interlayer thickness and pipe location have almost no influence on the performance of the pipe-embedded window.

Impacts of Vegetation on Quantity and Quality of Runoff from Green Roofs

As a key component of green roofs, vegetation may have significant impacts on both the quantity and quality of runoff. In this study, the effects of vegetation on both the quantity and quality of runoff from green roofs are investigated through monitoring the rainfall and runoff processes of green roofs with four different types of vegetation cover (Portulaca grandiflora, Sedum lineare, Festuca elata, and a non-vegetated bed as control) during 2017. The growth characteristics of the vegetation were also monitored, and the nutrients (NH4+-N, NO3--N, NO2--N, and PO43--P) and heavy metals (Cr, Cd, Cu, and Ni) in the rainwater and runoff were measured. The results show that the average rainfall event-based runoff reduction rates for the four green roof types were 51.3%, 41.5%, 36.3%, and 33.0%, respectively. Furthermore, the runoff reduction rates of the green roof planted with Portulaca grandiflora were significantly higher than both the Festuca elata green roof and the non-vegetated bed (P<0.05). The green roofs planted with Portulaca grandiflora and Sedum lineare both acted as sinks for the nutrients. The Portulaca grandiflora green roof, which had a higher biomass, provides higher nutrient load reduction rates (59.6%, 99.9%, 82.5%, and 25.7% for NH4+-N, NO3--N, NO2--N, and PO43--P, respectively) than the Sedum lineare green roof (52.5%, 89.3%, 75.3%, and 7.8%, respectively). The Festuca elata green roof and the non-vegetation bed acted as sinks for NH4+-N and NO2--N but were sources of NO3--N and PO43--P. All four of the green roofs were sinks for DCd, with pollution load reduction rates of 19.2%, 41.5%, 38.4%, and 31.1%, respectively. However, all the green roofs acted as the sources of DCr, DCu, and DNi.

폭염기간의 외부차양 설치에 따른 실내 열쾌적 및 냉방 부하 저감 성능 평가

Recent commercial buildings are suffer from thermal performance degradation and increased cooling load through windows expecially in the heat wave. One of the advanced approaches is to install an exterior shading system to block incoming solar radiation to the building. This study try to evaluate the thermal performance and the cooling load reduction effect when a EVB(External Venetian Blind) system is installed in a building in the heat wave. The evaluation was conducted in a real building for 4 weeks in the heat wave. Simulation was also conducted to see the performance in other conditions. As a result, PMV was improved by 0.51~0.62 from the experiment and cooling load reduction rate was evaluated about 11%~39% from the simulation study.

Remediation and accumulation characteristics of dissolved pollutants for stormwater in improved bioretention basins

Dissolved pollutants in stormwater are more mobile/bioavailable, and are captured via different mechanisms than particles. Column-scale bioretention basins are constructed by filling different media, which is used to study the remediation and accumulation characteristics of dissolved pollutants by improved bioretention basins (increased infiltration and adsorption capacity of the media). The media factor (ratio of specific surface area to cubic of porosity) is used to characterize the basic properties of different media, while considering the key factors: infiltration capacity, inflow concentration, recurrence interval, discharge ratio, antecedent dry period, and rainfall duration. The results showed that stormwater pollutants load reduction rate decreased with the increase of recurrence interval and discharge ratio, and increased with the increase of inflow concentration. Based on response surface methodology (RSM), a quantitative relationship model between major pollutants and influencing factors were established (R2 > 0.715), which can be used to estimate the design and operation of the media. By detecting changes in media carbon, nitrogen and phosphorus contents, the results showed that partial pollutants leaching were greater than their accumulation in the initial stage of system operation, and their contents in the media reduced during simulated rainfall. After the pollution contents tend to stabilize, the accumulated pollutants were greater than the leaching, and media pollution contents showed the trend of upper > middle > lower (corresponding to the 10, 35, and 60 cm sections of the media from top to bottom). Six enzymes closely related to the accumulation and migration of nitrogen, phosphorus and organic matter in the media were selected. Pearson correlation analysis found that: the significant correlations between the selected enzyme activity and pollutants were not consistent in bioretention system. For example, catalase was significantly correlated with all the pollutants (P < 0.01), whereas acid phosphatase was not significantly correlated with all the pollutants.

Retention Efficiency of Vegetative Filter Strips for Nitrogen in Danjiangkou Reservoir Area, Central China

Abstract To investigate the retention efficiency and mechanism of nitrogen of Vegetative filter strips (VFSs) in the Danjiangkou Reservoir area, simulated runoff discharging experiments were carried out in a new-established Bermuda VFS. The results showed that the Bermuda VFS reduced 73.1-86.1 % of surface runoff through infiltration. The outflow rate of runoff increased first and then became stable with time. The concentration reduction rates (CRRs) and load reduction rates (LRRs) of NH3-N increased initially and then decreased with the increase of inflow concentration. The average CRRs and LRRs of NH3-N in three treatments ranged 66.1-90.3 % and 90.0-96.7 %, respectively. The concentration reduction of NH3-N was primarily achieved by soil adsorption. The optimal inflow concentration of NH3-N for the optimum CRR was between 0.65 and 3.52 mg/dm3. The CRRs and LRRs of NO3-N fluctuated between 6.8-14.0 % and 72.0-77.9 % in three treatments. The concentration reduction of NO3-N was primarily achieved by plant uptake and soil microbe assimilation. The optimal inflow concentration of NO3-N for optimum CRR exceeded 6.78 mg/dm3. The CRRs and LRRs of TN increased with the increase of inflow concentrations. The average CRRs in the low, moderate and high treatments reached 9.7, 14.8 and 27.4 %, respectively, and the average LRRs reached 72.1, 74.3 and 81.2 %, respectively. The optimal inflow concentration of TN for optimum CRR exceeded 10.21 mg/dm3. The study showed that Bermuda grass can retain nitrogen in runoff efficiently and should be promoted around the Danjiangkou reservoir.

Dynamic response analysis of the wind–train–bridge coupling based on the stiffness change of the long-span track bridge

In order to analyze the influence of the stiffness change of the long-span track bridge on running safety of the train, a bridge and train analysis model, based on Chongqing Egongyan track bridge, is established to simulate and evaluate the spatial coupling dynamic response of the wind–train–bridge system through stiffness change and to propose the reasonable stiffness limit range of the long-span track suspension bridge. The results show that the dynamic characteristics of the bridge are good, and the safety of train operation and ride comfort meet the requirements when the vertical stiffness is 1/300–1/500 and the lateral stiffness is 1/600–1/1200; the dynamic response of the bridge and the running safety of the train are significantly sensitive to the stiffness change of the bridge, especially when the wind speed is 25 m/s and the vertical stiffness is 1/300, at this time, the derailment coefficient and the wheel load reduction rate reach 0.72 and 0.54, respectively, which are close to the limit standard, indicating that there are some potential safety hazards in train operation.

Nitrogen retention and purification efficiency from rainfall runoff via retrofitted bioretention cells

Nitrogen processing in the bioretention media is often variable, and the contribution to nitrogen retention and loss remains unclear. Bioretention cells including 12 medium combinations were constructed following ten intermittent, simulated storm events, meanwhile, the contents of pollutants and related enzyme activities in the media were detected. Among these medium combinations, C-04 ∼ C-12 were retrofitted media, which comprised a mixture of modifiers and traditional bioretention soil mixing (BSM). Among them, BSM + Water treatment residual (WTR), BSM + Green zeolite, BSM + Flyash, BSM + Vermiculite, and BSM + Turfy were recommended for reducing and purifying stormwater runoff, especially for nitrogen pollutants (more than 63.4%). Considering the inflow/outflow pollutant load, the total nitrogen (TN) load reduction rates of retrofitted media were 10% higher than that for BSM, however, the changes of TN mass in these media were significantly different before and after the tests, and TN losses for BSM + Flyash, BSM + Turfy, BSM + Coconut husk, BSM + Medical + Turfy, and BSM + Green zeolite + Turfy were more pronounced than that for others. Under ammonization, nitrification, denitrification, or leaching, the mass of TN and total organic nitrogen (TON) in the media decreased by 0.54% to 58.3% (median = 8.1%) and 5.3% to 98.6% (median = 52.8%) during the tests, respectively. On the contrary, the mass of ammonium (NH4+-N) increased in the media from 1.2% to 5.4% (median = 2.2%). Under the impact of simulated rainfall, the activities of urease, protease, dehydrogenase, and catalase increased, however, the activities of invertase and acid phosphatase decreased. This study will contribute to a greater understanding of the runoff pollutants purification mechanism in bioretention systems.

An experimental study about structural behavior of CFRP Bar embedded into wood surface

ABSTRACTRecently there has been an increase in people’s interest in friendly-environment wooden-structure buildings due to changes in the diversified housing environment. Resulting from such increased interest . there is also growth in the amount of consumed and imported woods required for various designs of wooden buildings. However, due to lack of experience in designing such buildings, many problems have arisen, including excessive dependence on traditional wooden architectures. This study conssiders the construction method of inserting a CFRP Bar into the wooden surface. From a comparison of maximum internal force, the experimental specimen group reinforcing the lateral side and the bottom side of wood showed an increased maximum internal force over 50% more than the non-reinforced specimen group, so it is known that if the load reduction rate, ΔPmax is increased, the transformation rate of CFRP Bar is increased. From this result, it is also known that the CFRP Bar properly distributes the external force being exercised from outside, and this proposed construction method is effective.

Research on Parameters of the Curve Negotiation Performance of High-Speed Train Composed of Multiple Vehicles

This paper calculates the wheel/rail nonlinear numerical solution that both changes in trend or in values are relatively consistent conclusion, using different methods of comparative analysis of the cycle dynamics system for studying the influence of the curve negotiating velocity and orbital parameters on the performance of high-speed train. Then based on single-section vehicle system program, a high-speed train coupling system considering vehicle terminal connection device is established. The influence of curve negotiating velocity and orbital parameters on the performance of high-speed train is analyzed. The results show that, with the curve negotiating velocity increasing, the derailment coefficient, rate of wheel load reduction, and the vertical force of wheel rail have a tendency to rise after falling first, lateral force of wheel rail monotone increasing. When the vehicle is in a superelevation state, the indicators are slightly lower than the equilibrium state. While the indicators with parameters change significantly when the vehicle is in a underelevation state. For instance, when the radius of the curve is 5000m to the radius 6700m, the derailment coefficient increases by 53.6% and rate of wheel load reduction is increased by 44.1%.

Dynamic Responses of Vehicle‐CRTS III Slab Track System and Vehicle Running Safety Subjected to Uniform Seismic Excitation

The dynamic model for the vehicle‐CRTS III slab track system is established subjected to uniform seismic excitation, and the calculation program with MATLAB is compiled and verified. The influences of track parameters, seismic intensity, and running speed of the vehicle on the dynamic responses of the system and the vehicle running safety are analyzed. The results show that (1) the track parameters have certain influence on the dynamic responses of the system, and the seismic intensity and the running speed of the vehicle have important influence on the vehicle running safety; (2) the derailment coefficient is highly sensitive to seismic intensity, and the wheel load reduction rate is also highly sensitive to the running speed of the vehicle.

Assessing the effects of subgrade frost heave on vehicle dynamic behaviors on high-speed railway

The subgrade frost heave of high-speed railways has an inevitable effect on track irregularity in severely cold regions. To research the influence of the subgrade frost heave on the dynamic behavior of high-speed railway vehicles, a multi-body dynamics rigid vehicle model and the finite element method flexible track model are coupled using the rigid-flexible coupling dynamics method. The typical frost heave deformation is used as the excitation source, and the effects on dynamic behaviors of the wheel/rail system are analyzed considering various conditions of frost heave, slab track stochastic irregularity, and train speed. The calculation results show that subgrade frost heave has a significant influence on the safety index (the vertical wheel/rail force and the wheel load reduction rate) and the stability index (the vertical acceleration of the carbody and the vertical sperling index) of the vehicle. Both the safety index and the stability index increases linearly as the frost heave amplitude grows and decreases nonlinearly as the frost heave wavelength grows. The safety index is more sensitive to the wavelength, while the stability index is more sensitive to the amplitude. The frost heave region that has an amplitude greater than 15 mm and a wavelength of less than 15 m should be focused on more. Compared to the frost heave deformation, the growth of slab track stochastic irregularity has greater influence on the vertical wheel/rail force. The influence on the other vertical indexes are relatively insignificant. Higher train speeds lead to a worse safety and stability index, and slowing down the speed is an effective way to ensure the safe and stable operation of the high-speed vehicle.

Dynamic behavior of a polyurethane foam solidified ballasted track in a heavy haul railway tunnel

Dynamic behavior of a new type of track using the polyurethane foam solidified ballast in heavy haul railway tunnels is comprehensively investigated in this study. First, a dynamic model of the vehicle–track–tunnel interaction system was developed based on the multi-body system dynamics theory and finite element method. Then, the dynamic effects of the polyurethane foam solidified ballast track on the train and the surrounding infrastructures were calculated and compared to those of the traditional ballasted track. Moreover, the effects of the elastic modulus and the solidified area size of polyurethane foam solidified ballast on the dynamic behavior were analyzed. Results show that, compared to the traditional ballast bed, polyurethane foam solidified ballast decreases the track stiffness and the vibration acceleration of the tunnel, while does not affect the vehicle safety (derailment coefficient and the rate of wheel load reduction). A larger elastic modulus of polyurethane foam solidified ballast has little effects on the wheel–rail interaction and the vibration acceleration of the tunnel, while a smaller modulus results in amplification of the displacements of rails and sleepers. Considering the vehicle–track interaction and tunnel vibration, the optimal elastic modulus of polyurethane foam solidified ballast is suggested to be 60–80 MPa. In addition, smaller solidified area of polyurethane foam solidified ballast presents lower effects on the vibration reduction and rate of wheel load reduction, while larger area leads to a higher derailment coefficient and cost. Therefore, an optimal solidified area size of polyurethane foam solidified ballast with the top width of 0.85 m is recommended.

Dynamic Responses of 87-Type Railway Steel Beam for Rush-repair under Heavy Load Trains

87-type railway steel beam for rush-repair were established by the finite element analysis software ANSYS and five different spans of beams were taken into consideration in the research of dynamic responses. DF4 locomotive hauling C70 freight heavy load marshalling trains model was established by dynamics software UM, in which specific wheel and rail relationship was used to found a combined simulation vibration system. After modeling, process of train running through the bridge was simulated to study several indexes including mid-span vertical deflection, mid-span lateral amplitude, derailment coefficient, rate of wheel load reduction and lateral force of wheel. These indexes made it possible to find out the changing pattern and the conclusion of maximum recommended speed.

Influence of slab arch imperfection of double-block ballastless track system on vibration response of high-speed train

According to the structural damage characteristics of ballastless track of high-speed railway by investigation, a novel method for evaluating the influence of ballastless track of high-speed railway is presented. The dynamic model of ballastless track with damage property is established based on train-track spatial vibration system. The calculated and in situ tested results were compared to certify the model and computation program. Taking the track slab imperfections occurred in a tunnel along the real high-speed railway as an example, the influence of vibration responses of the train-track system with slab imperfections under different conditions is calculated and analyzed in comparison with normal slab. In addition, the maintenance effect on the repaired track structure is evaluated by considering the operate safety and comfort of high-speed train. It is concluded that large amplitude of slab arch imperfection results in higher acceleration of slab and car body. Therefore, train operation speed should be controlled in accordance with the safety standard such as wheel load reduction rate and derailment coefficient. In the case of low amplitude of slab arch imperfection, train operation speed should be controlled in accordance with the comfort standard such as Sperling index. The specific operation velocities were given correspondingly. Therefore, the mechanism and conclusions above can forecast intuitively in the field of track maintenance. The paper proposes a practical and valuable method for evaluating double-block ballastless track of high-speed railway.

Simulation of the hydrological and environmental effects of a sponge city based on MIKE FLOOD

Based on the pilot area of a sponge city in Northwest China, the MIKE FLOOD models of urban flood and nonpoint source pollution are established. The uncertainty analysis of model shows that such parameters as hydrological reduction factor, imperviousness, and decay constant have big influences on the total runoff, peak flow, and water quality. The measured data of the rainfall events 20160724 and 20160623 are used to calibrate and validate the model. The correlation coefficients (R 2 ) and Nash–Sutcliffe efficiency coefficient (Ens) are both over 0.65. The changes in urban rainwater runoff and water quality for different rainfall conditions under traditional development (TD) and low impact development (LID) modes are simulated. The results show that: (1) Compared with TD mode, for different rainfall conditions under LID mode, the reduction rates of overflow and the overload pipes are, respectively, 22.4–100 and 0–54.55% when the area proportion of LID measures is 17.76%. The total runoff reduction rate is 64.01–81.52%, the peak flow reduction rate is 0–69.09%, and the flood peak time is delayed by 0–48 min. (2) Compared with TD mode, after adding LID measures, the load reduction rates of total suspended solids (SS), chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) are increased by 19.20–68.71, 19.19–67.78, 18.72–60.91, and 19.89–68.75%, respectively. The effluent reduction rates of the event mean concentrations (EMCs) of SS, COD, TN, and TP are increased by 0.65–42.07, 0.65–40.34, 0.06–27.62, and 1.51–42.14%, respectively. (3) The LID measures have certain control on waterlogging situation, and the submerged area under different water depths and flooding durations are decreased by 11.11–100 and 32.23–100%, respectively. For 19.2 mm rainfall event, under the LID mode, the SS load reduction rate achieves 60%, and rainfall runoff is all assimilated without discharge and waterlogging phenomena. LID measures have a better control effect on water quality and water quantity of urban rainstorm runoff; however, the effect of LID measures will reduce with the increase in recurrence interval.

Fundamental Tradeoff Between Storage and Latency in Cache-Aided Wireless Interference Networks

This paper studies the fundamental tradeoff between storage and latency in a general wireless interference network with caches equipped at all transmitters and receivers. The tradeoff is characterized by an information-theoretic metric, \emph{normalized delivery time} (NDT), which is the worst-case delivery time of the actual traffic load at a transmission rate specified by degrees of freedom (DoF) of a given channel. We obtain both an achievable upper bound and a theoretical lower bound of the minimum NDT for any number of transmitters, any number of receivers, and any feasible cache size tuple. We show that the achievable NDT is exactly optimal in certain cache size regions, and is within a bounded multiplicative gap to the theoretical lower bound in other regions. In the achievability analysis, we first propose a novel cooperative transmitter/receiver coded caching strategy. It offers the freedom to adjust file splitting ratios for NDT minimization. We then propose a delivery strategy which transforms the considered interference network into a new class of cooperative X-multicast channels. It leverages local caching gain, coded multicasting gain, and transmitter cooperation gain (via interference alignment and interference neutralization) opportunistically. Finally, the achievable NDT is obtained by solving a linear programming problem. This study reveals that with caching at both transmitter and receiver sides, the network can benefit simultaneously from traffic load reduction and transmission rate enhancement, thereby effectively reducing the content delivery latency.