Prediction of the color variation of moso bamboo during CO2 laser thermal modification

Thermal modification is widely used for bamboo materials as an efficient modification method. CO2 laser with the advantages of high energy density, short process period, non-pollution, etc. could be applied as a novel thermal treatment for wooden and bamboo materials processing. The laser intensity argumentation of power, motion arguments of feed rate, and sweep width for laser emitter were selected as input arguments for treating the Moso bamboo surface. The lightness variation and total color variation (∆L* and ∆E*) were collected using a portable colorimeter to describe the bamboo surface color variation after laser irradiation. Response surface methodology was chosen for designing experiments and modeling. The results showed that the increase of laser power had a positive influence on increasing the absolute values of ∆L* and ∆E*, but the feed rate of laser emitter and sweep width increasing had opposite effects on absolute values of ∆L* and ∆E*. The quadratic models of ∆L* and ∆E* created by response surface methodology were competent for describing the relationship between laser processing arguments and color indexes of ∆L* and ∆E*. This approach will be useful for selecting suitable and desirable processing arguments to get the surface color of bamboo productions.

Characterization of Frequency-Chirped Dynamic Nuclear Polarization in Rotating Solids

Continuous wave (CW) dynamic nuclear polarization (DNP) is used with magic angle spinning (MAS) to enhance the typically poor sensitivity of nuclear magnetic resonance (NMR) by orders of magnitude. In a recent publication we show that further enhancement is obtained by using a frequency-agile gyrotron to chirp incident microwave frequency through the electron resonance frequency during DNP transfer. Here we characterize the effect of chirped MAS DNP by investigating the sweep time, sweep width, center-frequency, and electron Rabi frequency of the chirps. We show the advantages of chirped DNP with a trityl nitroxide biradical, and a lack of improvement with chirped DNP using AMUPol, a nitroxide biradical. Frequency-chirped DNP on a model system of urea in a cryoprotecting matrix yields an enhancement of 142, 21% greater than that obtained with CW DNP. We then go beyond this model system and apply chirped DNP to intact human cells. In human Jurkat cells, frequency-chirped DNP improves enhancement by 24% over CW DNP. The characterization of the chirped DNP effect reveals instrument limitations on sweep time and sweep width, promising even greater increases in sensitivity with further technology development. These improvements in gyrotron technology, frequency-agile methods, and in cell applications are expected to play a significant role in the advancement of MAS DNP.<br>

Characterization of Frequency-Chirped Dynamic Nuclear Polarization in Rotating Solids

Continuous wave (CW) dynamic nuclear polarization (DNP) is used with magic angle spinning (MAS) to enhance the typically poor sensitivity of nuclear magnetic resonance (NMR) by orders of magnitude. In a recent publication we show that further enhancement is obtained by using a frequency-agile gyrotron to chirp incident microwave frequency through the electron resonance frequency during DNP transfer. Here we characterize the effect of chirped MAS DNP by investigating the sweep time, sweep width, center-frequency, and electron Rabi frequency of the chirps. We show the advantages of chirped DNP with a trityl nitroxide biradical, and a lack of improvement with chirped DNP using AMUPol, a nitroxide biradical. Frequency-chirped DNP on a model system of urea in a cryoprotecting matrix yields an enhancement of 142, 21% greater than that obtained with CW DNP. We then go beyond this model system and apply chirped DNP to intact human cells. In human Jurkat cells, frequency-chirped DNP improves enhancement by 24% over CW DNP. The characterization of the chirped DNP effect reveals instrument limitations on sweep time and sweep width, promising even greater increases in sensitivity with further technology development. These improvements in gyrotron technology, frequency-agile methods, and in cell applications are expected to play a significant role in the advancement of MAS DNP.<br>

Effective sweep-width for barrier missions against an evasive target

An effective sweep-width, to be used in predicting the performance of a barrier patrol against a smart, evasive intruder is defined. Following Washburn’s example for a two-dimensional area search, the nominal sweep-width of the searcher is reduced to account for the target’s evasive ability. The formulation presented here allows for the barrier to be either stationary or advancing. Two different definitions are offered for an effective sweep-width: one that focuses solely on the probability of detecting the intruder and one that includes deterrence as a form of success for the searcher.

ZONE OF SOIL LOOSENING WITH CULTIVATOR SWEEPS

Cultivator sweeps are placed remotely relative to each other or as parts of combined working tools with spherical discs, chisels and other parts, so the propagation of a zone of soil deformation during their operation at different depths and at different speeds is studied by designers for the calculation of technological runs in order to avoid their clogging with soil. (Research purpose) To determine the dependence of the width of the soil loosening zone with a cultivator sweep on the depth of travel and the speed of travel. (Materials and methods) Studies have been conducted on a stubble soil background after harvesting of winter wheat. Humidity and hardness of soil at a depth of 0 to 30 centimeters varied accordingly from 9 to 13 percent and from 0.28 to 0.87 MPa. The structure of the unit has been represented by the tractor MTZ Belarus 1221,2 and the cultivator KRN-5,6. Each section of the cultivator housed a universal sweep with a design working width of 220 mm. (Results and discussion) It has been found that a sweep forms a loosened strip and a strip of soil scattering, the width of which depends linearly on the tillage depth ranging from 10 to 22 cm and varies in the range from 31 to 42 and 38 to 58 cm, respectively. The unit travel speed ranging from 3 to 13 km/h does not affect the width of the loosening zone, and the zone of soil scattering increases according to the law of a weakly expressed quadratic parabola. The authors present empirical dependences of the width of the loosening and scattering zones on the tillage depth, the travel speed and the sweep width. (Conclusions) It has been found that the interval between the sweeps in one row should not be less than the specified width of the loosening zone, which has been confirmed as exemplified by a successful arrangement of working elements with a width of 410 mm on the combined units of the RVK series. Combined tools work with high technological reliability for sunflower stubble, without being clogged with soil and plant residues during the main field operations performed according to the minimal impact technology.

I smell a rat! Estimating effective sweep width for searches using wildlife-detector dogs

Context Dogs are often used to find rare or cryptic species, but search methods are not standardised, making it difficult to interpret and compare results. Standardised approaches are needed to optimise search effectiveness and/or efficiency. Designing an optimal search strategy requires knowledge of the effective sweep width, which is related to the probability of detection (POD) at various distances between the searcher and the search object. Aims Our primary aim was to estimate effective sweep width for wildlife-detector dogs searching for rodents. We also tested whether dogs differed in their reaction on encountering a laboratory rat (Rattus norvegicus) or a wild-caught Norway rat (wild-type R. norvegicus). Methods We conducted field trials using trained rodent-detector dogs to locate dead laboratory rats. We used the numbers of detections and non-detections at distances of 0–100 m to estimate detection probability and effective sweep width. Key results Dog teams located 100% of rats (regardless of strain) placed directly in their search path. POD declined rapidly with an increasing distance, yielding an observed detection rate of 33% at 10 m, and close to zero at ≥20 m. The data were best described by an exponential decay function. Effective sweep width was estimated to be 16.8 m (95% confidence interval 12.3–21.4 m), corresponding to a strip extending 8.4 m on either side of a walked track. Handlers could not consistently judge whether a dog had encountered a laboratory rat or a wild rat. Conclusions Our results suggest that when dogs are >10 m from a source of rat odour, POD declines sharply. We estimate that the effective distance explored when searching for a stationary rodent is 8.4 m either side of the search path. Implications This information will allow users to optimise the search pattern that dog teams should follow for a given search scenario.

Evaluation of Inter-Row Sweeps with Different Working Widths

Little information is available on the performance of inter-row sweeps. The aim of this study was to evaluate the potential of inter-row sweeps for mechanical weed control. Sweeps with different working widths (153, 280, and 330 mm) were tested at different working speeds (0.70, 1.53, and 2.22 m s-1) and a constant working depth (50 mm) in an indoor soil bin with a sandy loam soil. Measurements included soil disturbance characteristics: distance of soil throw (L), width of disturbed soil (W), mass of soil throw (M), height of soil ridge (H), and draft force (Fd). Results showed that L increased linearly with the working speed, but L was not affected by the working width of the sweeps. In contrast, W was slightly affected by the speed, but it was significantly increased if a wider sweep was used. Effects of working speed on M and H depended on the sweep width, and the smallest sweep traveling at 2.22 m s-1 resulted in the highest M and H. Draft force was higher for a wider sweep and a higher working speed. Considering the potential weeding efficiency (defined as the ratio of W and Fd), the width of sweep would not make any differences, and a lower working speed would result in better performance. Keywords: Draft force, Inter-row, Soil disturbance, Speed, Sweep, Weeding.

A New Microwave Asphalt Radar Rover for Thin Surface Civil Engineering Applications

This paper presents a beyond state-of-the-art, sweeping microwave asphalt radar mounted on a small radio controlled four-wheel-drive rover. The quasi-monostatic, remote-controllable radar operates at Ku-band and has an output power of +10 dBm. Detection follows the zero intermediate frequency principle. The sweep width allows for a depth resolution better than 10 mm. With its four microprocessors and laptop computer processing, the radar system can provide pavement permittivity data with an uncertainty close to 0.1. This is a considerable advancement when applying electromagnetic measurement techniques for applications where near surface or thin surface layer measurements are needed.