Analytical models for the penetration of semi-infinite targets by rigid,deformable and erosive long rods

A theoretical study is presented herein on the pen- etration of a semi-infinite target by a spherical-headed long rod for Yp 〉 S, where Yp is the penetrator strength and S is the static target resistance. For Yp 〉 S, depending upon initial impact velocity, there exist three types of penetration, namely, penetration by a rigid long rod, penetration by a deforming non-erosive long rod and penetration by an erosive long rod. If the impact velocity of the penetrator is higher than the hydrodynamic velocity （VH）, it will penetrate the target in an erosive mode; if the impact velocity lies between the hydrodynamic velocity （VH） and the rigid body velocity （VR）, it will penetrate the target in a deformable mode; if the impact velocity is less than the rigid body velocity （VR）, it will penetrate the target in a rigid mode. The critical conditions for the transition among these three penetration modes are proposed. It is demonstrated that the present model predictions correlate well with the experimental observations in terms of depth of penetration （DOP） and the critical transition conditions.

Novel rodent models of penetrating traumatic brain injury

A penetrating traumatic brain injury（pTBI）occurs when an object impacts the head with sufficient energy to penetrate skin,cranial bone and meninges to inflict injury directly to the brain parenchyma.This type of injury is particularly common in areas plagued by armed conflicts or gun-related violence.

Is laparoscopy equal to laparotomy in detecting and treating small bowel injuries in a porcine model?

AIM: To evaluate the safety and effectiveness of laparoscopy compared with laparotomy for diagnosing and treating small bowel injuries (SBIs) in a porcine model. METHODS: Twenty-eight female pigs were anesthetized and laid in the left recumbent position. The SBI model was established by shooting at the right lower quadrant of the abdomen. The pigs were then randomized into either the laparotomy group or the laparoscopy group. All pigs underwent routine exploratory laparotomy or laparoscopy to evaluate the abdominal injuries, particularly the types, sites, and numbers of SBIs. Traditional open surgery or therapeutic laparoscopy was then performed. All pigs were kept alive within the observational period (postoperative 72 h). The postoperative recovery of each pig was carefully observed. RESULTS: The vital signs of all pigs were stable within 1-2 h after shooting and none of the pigs died from gunshot wounds or SBIs immediately. The SBI model was successfully established in all pigs and definitively diagnosed with single or multiple SBIs either by exploratory laparotomy or laparoscopy. Compared with exploratory laparotomy, laparoscopy took a significantly longer time for diagnosis (41.27 ± 12.04 min vs 27.64 ± 13.32 min, P = 0.02), but the time for therapeutic laparoscopy was similar to that of open surgery. The length of incision was significantly reduced in the laparoscopy group compared with the laparotomy group (5.27 ± 1.86 cm vs 15.73 ± 1.06 cm, P < 0.01). In the final post-mortem examination 72 h after surgery, both laparotomy and laparoscopy offered a definitive diagnosis with no missed injuries. Postoperative complications occurred in four cases (three following laparotomy and one following laparoscopy, P = 0.326). The average recovery period for bowel function, vital appearance, and food re-intake after laparoscopy was 10.36 ± 4.72 h, 14.91 ± 3.14 h, and 15.00 ± 7.11 h, respectively. All of these were significantly shorter than after laparotomy (21.27 ± 10.17 h, P = 0.004; 27.82 ± 9.61 h, P < 0.001; and 24.55 ± 9.72 h, respectively, P = 0.016). CONCLUSION: Compared with laparotomy, laparoscopy offers equivalent efficacy for diagnosing and treating SBIs, and reduces postoperative complications as well as recovery period.

Fundamental Study on a Grout Penetration Model for a HLW Repository

In both the construction and operation phases of a repository for high-level radioactive waste, it will be important to constrain groundwater inflow using grouting technology that will be effective under the high groundwater pressure conditions deep underground. In this research, a review of existing grout penetration models in Japan and foreign countries and a trial analysis are conducted with a goal of describing the gout penetration with accuracy on site. Specifically, the applicability of the model developed by Gustafson ＆ Stille to the laboratory penetration tests was studied. The results show that the calculated values from the Gustafson ＆ Stille model agree well with values of laboratory penetration tests.

High-velocity projectile penetration test and theoretical calculation of pseudo fluid penetration of calcareous sand

To explore the penetration resistance of calcareous sand media,penetration tests have been conducted in the velocity range of 200-1000 m/s using conical-nosed projectiles with a diameter of 14.5 mm.Further,a pseudo fluid penetration model applicable to the penetration of rigid projectiles in sand media is established according to the approximate flow of compacted sand in the adjacent zone of penetration.The correlation between the impedance function of projectile-target interaction and the internal friction features of pseudo fluid is clarified,and the effects of sand density,cone angle of nose-shaped projectile,and dynamic hardness on the penetration depth are investigated.The results verify the feasibility,wide applicability,and much lower error(with respect to the experimental data)of the proposed model as compared to the Slepyan hydrodynamic model.

Application of artificial neural networks to the prediction of tunnel boring machine penetration rate

Rate of penetration of a Tunnel Boring Machine(TBM) in a rock environment is generally a key parameter for the successful accomplishment of a tunneling project.This paper presents the results of a study into the application of an Artificial Neural Network(ANN) technique for modeling the penetration rate of tunnel boring machines.A database,including actual,measured TBM penetration rates,uniaxial compressive strengths of the rock,the distance between planes of weakness in the rock mass and rock quality designation was established.Data collected from three different TBM projects(the Queens Water Tunnel,USA,the Karaj-Tehran water transfer tunnel,Iran,and the Gilgel Gibe II hydroelectric project,Ethiopia).A five-layer ANN was found to be optimum,with an architecture of three neurons in the input layer,9,7 and 3 neurons in the first,second and third hidden layers,respectively,and one neuron in the output layer.The correlation coefficient determined for penetration rate predicted by the ANN was 0.94.

Enhancing drug penetration in solid tumors via nanomedicine:Evaluation models,strategies and perspectives

Effective tumor treatment depends on optimizing drug penetration and accumulation in tumor tissue while minimizing systemic toxicity.Nanomedicine has emerged as a key solution that addresses the rapid clearance of free drugs,but achieving deep drug penetration into solid tumors remains elusive.This review discusses various strategies to enhance drug penetration,including manipulation of the tumor microenvironment,exploitation of both external and internal stimuli,pioneering nanocarrier surface engineering,and development of innovative tactics for active tumor penetration.One outstanding strategy is organelle-affinitive transfer,which exploits the unique properties of specific tumor cell organelles and heralds a potentially transformative approach to active transcellular transfer for deep tumor penetration.Rigorous models are essential to evaluate the efficacy of these strategies.The patient-derived xenograft(PDX)model is gaining traction as a bridge between laboratory discovery and clinical application.However,the journey from bench to bedside for nanomedicines is fraught with challenges.Future efforts should prioritize deepening our understanding of nanoparticle-tumor interactions,re-evaluating the EPR effect,and exploring novel nanoparticle transport mechanisms.

An engineering analysis of penetration of metal ball into fibre-reinforced composite targets

An engineering analysis of computing the penetration problem of a steel ball penetrating into fibre-reinforced composite targets is presented. Assume the metal ball is a rigid body, and the composite target is a transversely isotropic elasto-plastic material. In the analysis, a spherical cavity dilatation model is incorporated in the cylindrical cavity penetration method. Simulation results based on the modified model are in good agreement with the results for 3-D Kevlar woven （3DKW） composite anti-penetration experiments. Effects of the target material parameters and impact parameters on the penetration problem are also studied.

Simulations of vertical jet penetration using a filtered two-fluid model in a gas-solid fluidized bed

The influence of a vertical jet located at the distributor in a cylindrical fluidized bed on the flow behavior of gas and particles was predicted using a filtered two-fluid model proposed by Sundaresan and coworkers. The distributions of volume fraction and the velocity of particles along the lateral direction were investigated for different jet velocities by analyzing the simulated results. The vertical jet penetration lengths at the different gas jet velocities have been obtained and compared with predictions derived from empirical correlations; the predicted air jet penetration length is discussed. Agreement between the numerical simulations and experimental results has been achieved.

Design and analysis of firewall-penetrated scheme based on trusted host

On the basis of various firewall-penetrated technologies, a novel firewall-penetrated technology based on trusted host, which can realize the communication between penetrating host and protected host, is proposed in this paper. Meanwhile, the firewall-penetrated evaluating model and its formalized statement is also proposed by quantizing penetrated level, penetrated quality, and penetrated hiding. Finally, the fuewall-penetrated technology based on trusted host is analyzed under the fuewall-penetrated evaluating model, and the experimental results show that this technology has obvious penetrating effect and high penetrating quality.

Analysis and Prediction of Hole Penetrated in Thin Plates under Hypervelocity Impacts of Cylindrical Projectiles

The hole penetrated in thin metallic plates due to hypervelocity impacts of cylindrical projectiles was analyzed by experimental method.The projectile caused a hole-expanding effect when penetrating the target plate because of dynamic shear failure and extrusion.A new empirical model was presented to predict the perforation diameter in thin plates impacted by high-velocity cylindrical projectiles.The fitting coefficients resulted in a root-mean-square of 0.0641 and a correlation coefficient of 0.991.The errors between the predicted and the experimental values were less than 7.251%,and less than 4.705%for 93.333%cases of the dataset.The accuracy of the proposed model is much higher than that of Hill's model.Compared with historical equations,the new model is more accurate and can well describe the variations of different parameters with the normalized penetrated hole.The model takes into account the strength of materials,which contributes to the excellent results.This paper could provide important theoretical support for the analysis of the perforation process and its mechanism.