Ballistic trauma caused by military rifles: experimental study based on synthetic skull proxies

Rifles are often involved in violent deaths such as homicide and suicide. Consequently, expert knowledge and experimental forensic investigations are important to clarify the nature of ballistic trauma when applied to the human head and neurocranium. This study investigated differences in entrance wound morphology with Synbone® spheres which are described as being comparable to human flat bones. A series of ballistic experiments were conducted using two different rifle calibers (5.56 × 45 mm and 7.62 × 39 mm Full Metal Jacket (FMJ)). Synbone® spheres were used for close-range 0.3 m simulated executions as well as at 25 m and 35 m to simulate urban and military engagements. Results were compared with previously published experimental studies using similar military ammunition. In our study, entry wound morphology closely resembles real forensic cases compared to exit wound and overall shape morphology independently of the distance and the caliber. Circumferential delamination was clearly visible with full metal jacket (FMJ) rounds, yielding similar damage pattern morphology to the human crania. This study documented the presence of hydraulic burst or shock in all ten rounds from all three distances. Krönlein shots were also observed in some cases. Synbone® spheres constitute an acceptable synthetic surrogate for ballistic experiments. The present study offers new initial data on the behavior of Synbone® proxies in ballistic testing of military ammunitions; FMJ gunshot injuries to the human head, for distances that have not previously been published, suggesting that efficient tests can take place under these conditions. Further research on experimental ballistics with a larger number of controlled factors and multiple repetitions is recommended to verify the results of this pilot study before applied in forensic simulations.

Intervention Strategies for the Seismic Improvement of Masonry Buildings Based on FME Validation: The Case of a Terraced Building Struck by the 2016 Central Italy Earthquake

Residential masonry buildings represent a large stock among highly vulnerable structures in medium–high seismic hazard areas, often built without any anti-seismic provisions. Their rehabilitation and/or strengthening according to optimised intervention strategies is topical and may contribute to revaluating zones characterized by depopulation phenomena. In this paper, a terraced building struck by the 2016 Central Italy earthquake is analysed through a frame by macro element (FME) model. The building is composed of six two-storey units made of stone and clay block masonry walls and semi-rigid diaphragms. The numerical model was calibrated based on the damage pattern caused by the earthquake and then used to carry out parametric analyses on the strengthened conditions by simulating both one unit and the entire terrace. The effects of interventions applied to either vertical or horizontal components, both singularly and in combination, were analysed in terms of nonlinear static analyses, and quantified by a performance factor, according to the upgraded seismic code in Italy. Kinematic analyses also completed the assessment of the building. Results compared the capacity of interventions in attaining the targets defined for improvement at both local and overall levels.

Effect of Blast Loading on Seismically Detailed RC Columns and Buildings

Explosions caused by standoff charges near buildings have drastic effects on the internal and external structural elements which can cause loss of life and fatal injuries in case of failure or collapse of the structural element. Providing structural elements with blast resistance is therefore gaining increasing importance. This paper presents numerical investigation of RC columns with different reinforcement detailing subjected to near-field explosions. Detailed finite element models are made using LS-DYNA software package for several columns having seismic and conventional reinforcement detailing which were previously tested under blast loads. The numerical results show agreement with the published experimental results regarding displacements and damage pattern. Seismic detailing of columns enhances the failure shape of the column and decrease the displacement values compared to columns with conventional reinforcement detailing. Further, the effect of several modeling parameters are studied such as mesh sensitivity analysis, inclusion of air medium and erosion values on the displacements and damage pattern. The results show that decreasing the mesh size, increasing erosion value and inclusion of air region provide results that are very close to experimental results. Additionally, application is made on a slab-column multistory building provided with protective walls having different connection details subjected to blast loads. The results of this study are presented and discussed. Use of a top and bottom floor slab connection of protective RC walls are better than using the full connection at the four sides to the adjacent columns and slabs. This leads to minimizing the distortion and failure of column, and therefore it increases the chance of saving the building from collapse and saving human lives. Doi: 10.28991/cej-2021-03091733 Full Text: PDF

Discrete Rigid Block Analysis to Assess Settlement Induced Damage in Unreinforced Masonry Façades

In this study, a system of discontinuous rigid blocks is employed to simulate the possible damage mechanisms in unreinforced masonry (URM) façades and load-bearing frame systems subjected to settlement using the discrete element method (DEM). First, the employed modeling strategy is validated utilizing the available experimental results presented in the literature. Once there is a good agreement between the computational models and experimental findings, a sensitivity analysis is performed to quantify the influence of the input parameters defined in the DEM-based numerical model. Finally, the proposed modeling strategy is further utilized to assess the damage pattern that may develop in a URM façade due to uniform and non-uniform settlement profiles. The results of this study clearly show that the discrete rigid block analysis (D-RBA) provides robust numerical solutions that can be employed to visualize and assess the possible damage patterns and related collapse mechanisms of URM masonry systems as an alternative modeling strategy to standard continuum-based solutions.

The Influences of Projectile Material and Environmental Temperature on the High Velocity Impact Behavior of Triaxial Braided Composites

Two-dimensional (2D) triaxial braided composites with braiding angle (± 60°/0°) have been used as aero-engine containing casing material. In the current paper, three types of projectile with the same mass and equivalent diameter, including cylinder gelatin projectile, carbon fiber-reinforced plastics (CFRP), and titanium alloy blade-like projectile, were employed to impact on triaxial braided composites panels with thickness of 4.3 mm at room temperature (20 °C) to figure out the influences of projectile materials on the damage pattern and energy absorption behavior. Furthermore, the influences of environmental temperature were also discussed considering the aviation service condition by conducting ballistic impact tests using CFRP projectile at cryogenic temperature (−50 °C) and high temperature (150 °C). The triaxial braided target panel were pre-heated or cooled in a low-temperature chamber before mounted. It is found that soft gelatin project mainly causes global deformation of the target and therefore absorb much more energy. The triaxial braided composite absorb 77.59% more energy when impacted with CFRP projectile than that with titanium alloy projectile, which mainly results in shear fracture. The environmental temperature has influences on the damage pattern and energy absorption of triaxial braided composites. The cryogenic temperature deteriorates the impact resistance of the triaxial braided composite material with matrix cracking damage pattern, while high temperature condition improves its impact resistance with shearing fracture damage pattern.

Karakteristik Gambaran Histologis Paru-Paru Pasien COVID-19

Severe acute respiratory syndrome coronavirus (SARS-COV-2) is an infectious disease caused by coronavirus. Coronavirus (COVID-19) first attacks the upper respiratory system such as the nose, mouth, throat even the lungs and can trigger symptoms of fever and cough (pneumonia) resulting in changes in lung organ tissue during histological examination. This study aimed to determine the characteristics of the histological picture of the lungs of COVID-19 patients. This research uses a literature review research method. Based on 12 research reports analyzed in this research, the most common characteristic of histological features found in 12 research report journals is the finding of a diffuse alveolar damage pattern. Diffuse alveolar damage is a condition of acute lung injury which is accompanied by an acute phase with edema, a hyaline membrane, and inflammation followed by an organizing phase, where there is hyperplasia of type II pneumocytes, there is also fibrin or intra-alveolar protein. In conclusion, the characteristics of the histological features of the lungs most commonly found in COVID-19 patients are the findings of a diffuse alveolar damage pattern, which is a condition of acute lung injury and an acute phase with edema, hyaline membrane, and inflammation followed by an organizing phase, namely there is hyperplasia of type II pneumocytes, there is also fibrin or intra-alveolar proteinKeywords: lung histology, COVID-19. Abstrak: Severe acute respiratory syndrome coronavirus (SARS-COV-2) adalah sebuah penyakit menular yang disebabkan oleh coronavirus. Coronavirus (COVID-19) pertama kali menyerang sistem pernapasan bagian atas seperti hidung, mulut, tenggorokan bahkan sampai ke paru – paru dan dapat memicu gejala demam dan batuk (pneumonia) sehingga terjadi perubahan jaringan organ paru – paru pada saat dilakukan pemeriksaan histologi. Penelitian bertujuan untuk mengetahui karakteristik gambaran histologis paru – paru pasien COVID-19. Penelitian ini menggunakan metode penelitian literature review. Berdasarkan 12 laporan penelitian yang di analisis pada penelitian ini, karakteristik gambaran histologis yang paling umum ditemukan pada 12 jurnal laporan penelitian yaitu terdapat temuan pola diffuse alveolar damage. Diffuse alveolar damage merupakan kondisi cedera paru akut atau acute lung injury yang disertai dengan fase akut dengan adanya edema, terdapat membran hialin, dan inflamasi di ikuti dengan fase pengorganisasian yaitu terdapat hiperplasia pneumosit tipe II, juga terdapat fibrin atau protein intra-alveolar. Sebagai simpulan, karakteristik gambaran histologis paru – paru yang paling umum ditemukan pada pasien COVID-19 adalah temuan pola diffuse alveolar damage yang merupakan kondisi cedera paru akut atau acute lung injury serta fase akut dengan adanya edema, terdapat membran hialin, dan inflamasi di ikuti dengan fase pengorganisasian yaitu terdapat hiperplasia pneumosit tipe II, juga terdapat fibrin atau protein intra-alveolarKata Kunci: histologi paru, COVID-19

Connection Damage Detection of Double Beam System under Moving Load with Genetic Algorithm

In this paper, a novel damage detection approach for the spring connection of the double beam system using the dynamic response of the beam and genetic algorithm is presented. The double beam system is regarded as both Bernoulli-Euler beams with simply supported ends, the upper and lower beams are connected by a series of linear springs with certain intervals. With the genetic algorithm, the dynamic acceleration response of double beam system under moving load, which can be solved by the Newmark-β integration procedure, is used as the input data to detect the connection damage. Thus the dynamic response of the double beam system with a certain damage pattern can be calculated employing the moving load model. If the calculated result is quite close to the recorded response of the damaged bridge, this damage pattern will be the solution. The connection damage detection process of the proposed approach is presented herein, and its feasibility is studied from the numerical investigation with simple and multiple damages detection. It is concluded that the sophisticated damage conditions need much longer time to detect successfully.

Analysis of Lithium-ion Battery Micro-overcharge Cycle Damage Mechanism Based on Electrochemical Impedance Spectroscopy

Electrochemical impedance spectroscopy (EIS) was used to study the micro-overcharge cycle damage mechanism of Lithium-ion batteries (LIBs). Micro-overcharge cycle experiments of LIBs were carried out, and the capacity fading of LIBs under different charging cut-off voltages were analyzed. It was found that the capacity fading rate of LIBs increased with the rising of overcharge cut-off voltages and the increasing of cycle numbers. The EIS results show that the main damage pattern of LIBs during micro-overcharge cycle is the active lithium loss when the cut-off voltage is between 4.3 V and 4.4 V. Lithium loss accounts for more than 80% damage proportion when LIBs cycling for more than 20 cycles.