Damage to Residual Trees in Thinning of Broadleaf Stand by Mechanised Harvesting System

This research was conducted to determine the cause, intensity and location of damage (stem, butt end, root collar, root) and the extent of damage to standing trees during felling and processing by an harvester and timber extraction by a forwarder (cut-to-length system). The research was conducted in the central part of the Republic of Croatia in the Management Unit (MU) “Bjelovarska Bilogora” during the thinning of Subcompartment 14b, area of 18.28 ha, in the stand of hornbeam (Carpino betuli—Quercetum roboris fagetosum Rauš 1975), age 70, and of Subcompartment 14c, area of 9.07 ha, in a stand of common beech (Carici pilosae—Fagetum Oberdorfer 1957) aged 79 years. The thinning intensity was 12.13% in Subcompartment 14b and 13.72% in Subcompartment 14c. Field measurements were carried out on sample plots—the first time in 2017 to determine the intensity and characteristics of the damage to standing trees with regard to the cause of the damage (harvester or forwarder), and the second time in 2018 to determine the overall intensity and features of the damage to standing trees after finishing harvesting operations. For all trees remaining in the stand after the harvesting operations, the following were determined: tree species, diameter at breast height (DBH), the position of the tree in the stand depending on the forest traffic infrastructure, and—if damaged—cause of damage, type of damage, the position of damage on the tree, and dimensions of damage. The intensity of the damage was expressed by the ratio of damaged and undamaged trees, with a detailed analysis of bark damage (squeezed-bark damage and peeled-bark injuries). The results of the research indicate the highest prevalence of peeled-bark injuries. In relation to the total number of standing trees, trees with peeled-bark injuries were more represented in Subcompartment 14c (39%) than in Subcompartment 14b (33%). In Subcompartment 14b, the harvester and the forwarder damaged an equal number of trees, while in Subcompartment 14c, the harvester damaged 59% of the damaged trees. In both subcompartments, an average of 83% of (peeled bark) injuries were up to 1.3 m above the ground. In both subcompartments, the most common (67%) were injuries up to 100 cm2 in size, for which many authors claim the tree can heal by itself. Given the increasing use of harvester-forwarder systems in deciduous stands and research results that indicate possible damage to standing trees, it is necessary to pay attention to all phases of planning and execution of timber harvesting operations, thus minimising negative effects.

Structure-driven effects on genomic DNA damage propensity at G-quadruplex sites

Our genome contains about half a million sites capable of forming G-quadruplex (G4) structures. Such structural formations, often localised at important regulatory loci, have high capability of altering the predisposition of corresponding genomic spans to endogenous and exogenous DNA damage. In this work, we devised an approach to systematically enrich and zoom onto structure-driven effects on the propensity to undergo 9 types of DNA damage: ultraviolet radiation-induced pyrimidine-pyrimidone (6-4) photoproduct PP and cyclobutane pyrimidine dimer CPD couplings (two dyad-based subtypes in each), cisplatin-mediated G-G crosslinks, reactive oxygen species induced 8-oxoguanine damage, DNA fragmentation upon natural decay and fossilisation, breakages from artificial enzymatic cleavage and ultrasound sonication. Our results indicate that the structural effects on DNA damageability at G4 sites are not a simple combination of shielding (G4 strand) and de-shielding (opposite strand) against damaging factors, and the outcomes have different patterns and variation from one damage type to another, highly dependent on the G4 strength and relative strand localisation. The results are accompanied by electronic structure calculations, detailed structural parallels and considerations.

Prediction of neck injury using multiple linear regression and bumper damage: Case study for low-speed rear-end collisions

The most frequent type of traffic accident is a low-speed rear-end collision, which can damage parts of the vehicle, including the bumper, and cause neck injury to the occupants. Even in minor damage accidents, such as scratches on bumper covers, 26.3% of occupants received treatment for bodily injuries whose main symptom was neck injuries through auto insurance. This study was conducted to evaluate the potential for neck injuries in low-speed accidents. Fifty-nine low-speed rear-end impact tests were conducted, and the motion of the struck vehicle and the neck injury criterion (NIC) of the occupant according to the test conditions were predicted using multiple linear regression derived via supervised machine learning. It was confirmed that the NIC can be predicted using vehicle motion values that can be obtained through an event data recorder. The coefficients of determination of the regression equations were 0.67–0.83. Lastly, we investigated whether neck injuries can be predicted through bumper cover damage that can be checked immediately after a vehicle accident. In the case of the vehicle damage type 1/2/3 category applied to auto insurance by the Korean government, an occupant would have a very low possibility of neck injury or symptoms. No symptoms or injuries were reported in the volunteer tests conducted for this study.

Generating and testing hypotheses about the fossil record of insect herbivory with a theoretical ecospace

A typical fossil flora examined for insect herbivory contains a few hundred leaves and a dozen or two insect damage types. Paleontologists employ a wide variety of metrics to assess differences in herbivory among assemblages: damage type diversity, intensity (the proportion of leaves, or of leaf surface area, with insect damage), the evenness of diversity, and comparisons of the evenness and diversity of the flora to the evenness and diversity of damage types. Although the number of metrics calculated is quite large, given the amount of data that is usually available, the study of insect herbivory in the fossil record still lacks a quantitative framework that can be used to distinguish among different causes of increased insect herbivory and to generate null hypotheses of the magnitude of changes in insect herbivory over time. Moreover, estimates of damage type diversity, the most common metric, are generated with inconsistent sampling standardization routines. Here we demonstrate that coverage-based rarefaction yields valid and reliable estimates of damage type diversity that are robust to differences among floral assemblages in the number of leaves examined, average leaf surface area, and the inclusion of plant organs other than leaves such as seeds and axes. We outline the potential of a theoretical ecospace that combines various metrics to distinguish between potential causes of increased herbivory. We close with a discussion of the most appropriate uses of a theoretical ecospace for insect herbivory, with the overlapping damage type diversities of Paleozoic gymnosperms and Cenozoic angiosperms as a brief case study.

IDENTIFIKASI KERUSAKAN TEGAKAN RAMIN (Gonystylus bancanus) DI PUNGGUALAS TAMAN NASIOANAL SEBANGAU KALIMANTAN TENGAH

The purpose of this study was to determine the damage to ramin (Gonystylus bancanus) stands in Punggualas Sebangau National Park, Central Kalimantan. The research location was determined by purposive sampling on the transect line at Punggualas. This observation is carried out by exploring the transect line that has been determined so that the data in the form of ramin stands can be found and the damage is observed in stages, then the coordinates of the ramin point are taken using GPS. In this observation, 22 ramin stands were found in which the most damage occurred in the leaves of ramin, namely as many as 35 cases of damage with the most damage type were leaf color changes as many as 20 cases of damage and with the most dominant severity level was 20-29%.From the dominant severity with a value of 20-29% it can be seen that the damage suffered by ramin stands is in the mild category.Tujuan dari penelitian ini adalah untuk mengetahui kerusakan tegakan ramin (Gonystylus bancanus) di Punggualas Taman Nasional Sebangau Kalimantan Tengah. Lokasi penelitian ditentukan secara purposive sampling pada jalur transek di Punggualas. Pengamatan ini dilakukan dengan cara menjelajah jalur transek yang sudah ditentuan agar data yang berupa tegakan ramin dapat ditemukan dan langsung diamati kerusakannya secara bertahap kemudian titik koordinat ramin diambil menggunakan GPS. Pada pengamatan ini ditemukan sebanyak 22 tegakan ramin yang mana kerusakan terbanyak terjadi pada bagian daun ramin yaitu sebanyak 35 kasus kerusakan dengan tipe kerusakan terbanyak adalah perubahan warna daun sebanyak 20 kasus kerusakan dan dengan tingakat keparahan paling dominan adalah 20-29%. Dari tingkat keparahan dominan dengan nilai 20-29% dapat diketahui bahwa kerusakan yang diderita oleh tegakan ramin di Punggualas Taman Nasional Sebangau masuk dalam kategori ringan.

Scuffing load capacity calculation of worm gears

Worm gears with wheels of harder materials, such as cast iron or steel, are often prone to the damage type scuffing, which can cause a sudden and rapid failure of the gear box. Contact temperature is a suitable criterion to determine the scuffing safety for other types of gears. However, for worm gears, a scuffing load capacity calculation is not available at the moment. This paper presents a numerical temperature simulation for worm gears that considers transient multidimensional heat transfer and local frictional loading due to the contact. Based on the results of this simulation, this paper derives a simplified calculation of worm gear contact temperatures. The calculation only contains input parameters that are already part of current standards. Its result, the contact temperature of worm gears, can be used to rate the scuffing load capacity.

Application of Pulsed Thermography and Post-processing Techniques for CFRP Industrial Components

Several studies demonstrate the effectiveness of pulsed thermography for detection and visualization of sub-superficial flaws in composites. Continuous improvement of thermal data manipulation makes active thermography an attractive and powerful inspection method for industrial process control and maintenance aims. Therefore, temperature image-processing is the major ongoing challenge in the thermographic research field. However, the particular interest for thermographic inspections is to be more addressed to its simple and relatively fast industrial application; an appropriate image processing tool should be implemented and verified on industrial components, containing manufacturing and in-service defects. In the proposed research, well-established and previously proposed methods were analysed and compared for different defect typology inside three CFRP components. The main goal is not solely focused on establishing the suitable data processing approach, providing detection limits of processed data in terms of damage type, size and distribution. The aim of proposed work is to present detailed examples of thermal imaging methods applied on similar critical defects, evaluating different results among methods in terms of defects mapping capabilities and Tanimoto evaluation criterion, coupled also with the signal-to-noise ratio as assessment of defect detectability.

The Short-Circuit Protections in Hybrid Systems with Low-Power Synchronous Generators

Single-phase short-circuits are most often faults in electrical systems. The analysis of this damage type is taken for backup power supply systems, from small power synchronous generators. For these hybrid installations, there is a need for standard protection devices, such as fuses or miniature circuit breaker (MCB) analysis. Experimental research mentioned that a typical protective apparatus in low-voltage installations, working correctly during supplying from the grid, does not guarantee fast off-switching, while short-circuits occur during supplication from the backup generator set. The analysis of single-phase short-circuits is executed both for current waveform character (including sub-transient and transient states) and the carried energy, to show the problems with the fuses and MCB usage, to protect circuits in installations fed in a hybrid way (from the grid and synchronous generator set).

Feasibility Study of Selective Laser Melting for Metal Matrix Diamond Tools

Metal matrix diamond composite samples were fabricated by selective laser melting (SLM) at different forming parameters to investigate the feasibility and new challenges when SLM is applied to diamond tools manufacturing. The surface topographies, Rockwell hardness, compactness, microstructure, and diamond thermal damage of the samples were investigated in this study. The fabricated samples had high porosity and relatively low Rockwell hardness and compactness, and some ridge-shaped bulges and textures were observed at the edges and surfaces. Microstructure analyses showed that diamond particles were homogeneously distributed and metallurgically bonded within the metal matrix. The thermal damage pits on the diamond crystals along the scanning direction were the dominant damage type for SLM, which was completely different from conventional vacuum brazing and hot-pressing sintering. Although some challenges need to be further studied, our results demonstrate that SLM has great potential to propel the development of metal matrix diamond tools.