Effects of long-term fertilization on soil gross N transformation rates and their implications

Application of fertilizer has been found to significantly affect soil N cycling. However, a comprehensive understanding of the effects of long-term fertilization on soil gross N transformation rates is still lacking. We compiled data of observations from 10 long-term fertilization experiments and conducted a meta-analysis of the effects of long-term fertilization on soil gross N transformation rates. The results showed that if chemical fertilizers of N, P and K were applied in balance, soil p H decreased very slightly. There was a significantly positive effect of long-term fertilization, either chemical or organic fertilizers or their combinations, on gross N mineralization rate compared to the control treatment（the mean effect size ranged from 1.21 to 1.25 at 95% confidence intervals（CI） with a mean of 1.23）, mainly due to the increasing soil total N content. The long-term application of organic fertilizer alone and combining organic and chemical fertilizer could increase the mineralization-immobilization turnover, thus enhance available N for plant while reduce N losses potential compared to the control treatment. However, long-term chemical fertilizer application did not significantly affect the gross NH4＋ immobilization rate, but accelerated gross nitrification rate（1.19; 95% CI： 1.08 to 1.31）. Thus, long-term chemical fertilizer alone would probably induce higher N losses potential through NO3– leaching and runoff than organic fertilizer application compared to the control treatment. Therefore, in the view of the effects of long-term fertilization on gross N transformation rates, it also supports that organic fertilizer alone or combination of organic and chemical fertilizer could not only improve crop yield, but also increase soil fertility and reduce the N losses potential.

Influence of Heating Rate on Double Reversible Transformation in CuZnAlMnNi Shape Memory Alloy

The influence of heating rate on double reversible transformation in CuZnAlMnNi shape memory alloy was investigated by differential scanning calorimetry. It was found that rapid heating inhibits X -->M transformation but is favorable to the reverse martensite transformation, giving rise to the approach of the two transformation peaks. With the decrease of heating rate, the two transformation peaks separate gradually.

基于Transformer和CNN特征融合的非接触式心率检测算法

心率失调是心血管疾病的常见危险因素,如何及时地对心率失调作出预警,成为了研究的热点。传统的心率检测是接触式的,检测十分不便。远程光电容积脉搏波描记法(Remote photoplethysmography,rPPG)的提出旨在实现无须接触的测量,在许多场景中具有巨大的应用价值。然而,非接触式的测量方法容易受到环境和受试者运动的影响。针对这些问题,本文提出了基于Transformer全局表达和CNN局部特征融合的非接触式心率检测模型(TC-Net)。本文搭建了一个并联的Transformer网络和CNN网络的TC-Net模型。本模型包括两个分支,CNN分支用于提取rPPG信号的局部区域特征,Transformer用于提取rPPG信号的全局表达。由于全局表达特征和局部特征两者特征长度不一,本文提出了特征交互模块,该模块通过卷积层和上下采样模块以对齐两个分支的特征长度。随后,TC-Net通过特征交互模块将局部特征和全局表达进行融合得到最终用于检测的特征向量。最后,在远程心率测量评估中最广泛使用基准之一MAHNOB-HCI数据集上进行对比验证,模型在误差偏差(MAE)、均方根误差(RMSE)和平均绝对百分比误差(MAPE)等三个指标上都达到了最佳水平。因此,本文提出的非接触式心率检测模型TC-Net基于Transformer全局表达和CNN局部特征融合,具有较高的准确性和鲁棒性。此外,TC-Net仅由简单的几层卷积层和注意力层搭建而成,模型复杂度低,便于后续投入实际应用。

A MODEL FOR BAINITIC TRANSFORMATION KINETICS WITH PARABOLIC NUCLEATION RATE

Based on the assumptions of parabolic variation of nucleation rate versus time and transformation kinetics depending mainly on nucleation rate, a different model for bainitic transformation kinetics in hypoeutectoid steels was established. And this model was proved to be effective in the description of bainitic transformation by comparison with the result of conventional Avrami equation.

Cooling rate effects on the structure and transformation behavior of Cu-Zn-Al shape memory alloys

Different fragments of a hot-rolled and homogenized Cu–Zn–Al shape memory alloy（SMA） were subjected to thermal cycling by means of a differential scanning calorimetric（DSC） device. During thermal cycling, heating was performed at the same constant rate of increasing temperature while cooling was carried out at different rates of decreasing temperature. For each cooling rate, the temperature decreased in the same thermal interval. During each cooling stage, an exothermic peak（maximum） was observed on the DSC thermogram. This peak was associated with forward martensitic transformation. The DSC thermograms were analyzed with PROTEUS software： the critical martensitic transformation start（Ms） and finish（Mf） temperatures were determined by means of integral and tangent methods, and the dissipated heat was evaluated by the area between the corresponding maximum plot and a sigmoid baseline. The effects of the increase in cooling rate, assessed from a calorimetric viewpoint, consisted in the augmentation of the exothermic peak and the delay of direct martensitic transformation. The latter had the tendency to move to lower critical transformation temperatures. The martensite plates changed in morphology by becoming more oriented and by an augmenting in surface relief, which corresponded with the increase in cooling rate as observed by scanning electron microscopy（SEM） and atomic force microscopy（AFM）.

DECAY RATE OF FOURIER TRANSFORMS OF SOME SELF-SIMILAR MEASURES

This paper is concerned with the Diophantine properties of the sequence {ξθn}, where 1 ≤ξ 〈 θ and θ is a rational or an algebraic integer. We establish a combinatorial proposition which can be used to study such two cases in the same manner. It is shown that the decay rate of the Fourier transforms of self-similar measures μλ with λ = θ-1 as the uniform contractive ratio is logarithmic. This generalizes some results of Kershner and Bufetov-Solomyak, who consider the case of Bernoulli convolutions. As an application, we prove that μλ ahaost every x is normal to any base b ≥ 2, which implies that there exist infinitely many absolute normal numbers on the corresponding self-similar set. This can be seen as a complementary result of the well-known Cassels-Schmidt theorem.

任务驱动的轻量Transformer点云下采样方法

点云是一种重要的三维数据格式,能直观地描绘真实世界,然而点云的巨大数据量限制了其更加广泛的应用。为了简化点云并提高下游应用效率,提出了一种基于轻量级Transformer的任务驱动点云下采样方法。该网络包括特征提取模块和软采样模块,在特征提取模块中采用最先进的Transformer模型学习点云特征,考虑到计算和存储资源有限,将其设计为轻量化结构;在软采样模块中利用MLP和Gumbel-Softmax来模拟实际采样过程,得到下采样点云。为使采样点云适合后续应用任务,构造了一个包含任务损失、采样损失和约束损失的联合损失函数用于网络端到端训练。此外,为简化训练并方便实际应用,在基于轻量化Transformer的任务驱动点云下采样网络的基础上,还提出了多倍率下采样方法,它采用渐进式结构,结合多组采样损失,实现一个模型得到多个采样率下的点云。通过在ModelNet40和ShapeNetCore55数据集上进行点云分类任务和重建任务实验表明,所提方法在简化点云数量的同时,分类精度和重建精度得到良好保证,尤其是下采样点数较少时,相比于同类算法,任务性能更高。

Influence of temperature rate on transitory internal friction during reverse martensitic transformation for Ti_(50)Ni_(27)Cu_(23) alloy

Internal friction （IF） spectra during reverse martensitic transformation from 35 to 135°C at different temperature rates of 0.5,0.75,and 1°C/min for Ti50Ni27Cu23 shape memory alloy （SMA） samples were measured with a dynamic mechanical analyzer,respectively.The IF spectra were characterized by IF peak increasing progressively and peak shifting toward high temperature with an increase in temperature rate.An iterative approach was used to calculate the precise intrinsic and approximate transitory IF contributions to the normal IF spectrum.The quantitatively analyzed results indicate that the transitory IF of this alloy is nonlinearly dependent on the temperature rate and obeys a power law with a power coefficient of 0.55.The predicted and experimental IF spectra at different temperature rates of 0.75 and 1°C/min agree well with each other,respectively.

EFFECTS OF TEST TEMPERATURE AND STRAIN RATE ON THE MECHANICAL PROPERTIES IN AN INTERCRITICALLYHEAT-TREATED BAINITE-TRANSFORMED STEEL

Larger amount of austenite could be retained in an intercritically heat-treated bainite- transformed steel. The elongation and the strength-ductility balance of the steel could be enhanced considerably due to strain-induced martensite transformation and transformation- induced plasticity (TRIP) of retained austenite. The effects of test temperature and strain rate on the mechanical properties and strain induced transformation behavior of retained austenite in the steel were investigated. Total elongation and strength-ductility balance of the specimen reached maximum when it strained at a strain rate of 2.8×10-4s-1 and at 350℃. The relation between test temperature and tensile properties showed the same tendency at three kinds of strain rates. Flow stress increased considerably with decreasing the strain rate.

Chirp-Rate Resolution of Fractional Fourier Transform in Multi-component LFM Signal

Distinguishing close chirp-rates of different linear frequency modulation （LFM） signals under concentrated and complicated signal environment was studied. Firstly, detection and parameter estimation of multi-component LFM signal were used by discrete fast fractional Fourier transform （FrFT）. Then the expression of chirp-rate resolution in fractional Fourier domain （FrFD） was deduced from discrete normalize time-frequency distribution, when multi-component LFM signal had only one center frequency. Furthermore, the detail influence of the sampling time, sampling frequency and chirp-rate upon the resolution was analyzed by partial differential equation. Simulation results and analysis indicate that increasing the sampling time can enhance the resolution, but the influence of the sampling frequency can he omitted. What＇s more, in multi-component LFM signal, the chirp-rate resolution of FrFT is no less than a minimal value, and it mainly dependent on the biggest value of chirp-rates, with which it has an approximately positive exponential relationship.

Very Low Bit-Rate Video Coding Based on Wavelet Transform

Two video coding schemes based on wavelet transform achieving very low bit rate are presented in this paper. The first is a hybrid motion compensated wavelet transform(MC WT)system which behaves better at very low bit rates than the block DCT residual coder. The second is a new efficient coding system based on a simple frame differencing wavelet transform(FD WT)which performs well in both PSNR and visual quality with substantially reduced complexity.

马铃薯高效再生及遗传转化体系的优化

为优化马铃薯高效再生及遗传转化体系,研究鄂马铃薯3号茎段外植体在不同激素浓度配比下愈伤组织及分化情况,获得最佳愈伤组织及分化激素配比,再采用根癌农杆菌的遗传转化进行筛选,获得最佳转化体系,为马铃薯优质品种的基因工程育种提供依据。结果表明,不同激素浓度配比下愈伤组织及分化率差异较大,其中2.0 mg/L ZR+0.1 mg/L IAA激素配比下可高效再生出芽,出芽率高达100%,芽长势粗壮。通过构建植物表达载体pCambia1301,以GV3101为介导菌株,预培养2~3 d,共培养2~3 d,350 mg/L羧苄青霉素,50 mg/L卡那霉素筛选浓度转化效果较好,转化效率可达65%,其中转化苗在0.8 mg/L IBA+0.2 mg/L NAA激素配比的培养基中可形成再生植株,再生率达80%,苗茎粗壮,根系发达。

Improvement of Misclassification Rates of Classifying Objects under Box Cox Transformation and Bootstrap Approach

Discrimination and classification rules are based on different types of assumptions. Also, all most statistical methods are based on some necessary assumptions. Parametric methods are the best choice if it follows all the underlying assumptions. When assumptions are violated, parametric approaches do not provide a better solution and nonparametric techniques are preferred. After Box-Cox transformation, when assumptions are satisfied, parametric methods provide fewer misclassification rates. With this problem in mind, our concern is to compare the classification accuracy of parametric and non-parametric approaches with the aid of Box-Cox transformation and Bootstrapping. We carried Support Vector Machines (SVMs) and different discrimination and classification rules to classify objects. The attention is to critically compare the SVMs with Linear discrimination Analysis (LDA), and Quadratic discrimination Analysis (QDA) for measuring the performance of these techniques before and after Box-Cox transformation using misclassification rates. From the apparent error rates, we observe that before Box-Cox transformation, SVMs perform better than existing classification techniques, on the other hand, after Box-Cox transformation, parametric techniques provide fewer misclassification rates compared to nonparametric method. We also investigated the performances of classification techniques using the Bootstrap approach and observed that Bootstrap-based classification techniques significantly reduce the classification error rate than the usual techniques of small samples. Thus, this paper proposes to apply classification techniques under the Bootstrap approach for classifying objects in case of small sample. A real and simulated datasets application is carried out to see the performance.

Dynamics of Nitrogen Transformation and Removal in a Pilot High Rate Pond

The transformation and removal of nitrogen was studied in a pilot high rate pond with a surface area of 10.2 m2 and water depth of 60 cm. The pilot unit received wastewater from an existing field scale primary facultative pond at the University of Dar es Salaam. Wastewater samples were collected from the influent and effluent of high rate pond and were analyzed for physical-chemical parameters in the laboratory and in situ. An appropriate model complexity was selected, from which a conceptual model was then developed to model various processes in the system using STELLA 6.0.1 software. The study demonstrated that dominant nitrogen transformation processes in HRP were nitrification and denitrification, which transformed 0.95 and 0.87 gN/m2·d, respectively. These were followed by mineralization (0.37 gN/m2·d), ammonia uptake by microorganisms (0.34 gN/m2·d), volatilization (0.30 gN/m2·d), sedimentation (0.24 gN/m2·d), and regeneration (0.15 gN/m2·d). Uptake of nitrate was not observed because of microorganisms preference for ammonia, which was abundant in the pond. The major nitrogen transformation mechanisms in high rate pond were denitrification, net sedimentation and volatilization, which accounted for 69.1%, 7.1% and 23.8% of the total permanent removal mechanisms of nitrogen in High Rate Pond.

3-D Wavelet Transform for Very Low Bit-Rate Video Coding

A new improved Goh's 3 D wavelet transform(WT) coding scheme is presented in this paper. The new scheme has great advantages including a simple code structure, low computation cost and good performance in PSNR, compression ratios and visual quality of reconstructions, when compared to the other existing 3 D WT coding methods and the 2 D WT based coding methods. The new 3 D WT coding scheme is suitable for very low bit rate video coding.

Very Low Bit Rate Video Coding Using Motion Compensated 3 D Wavelet Transform

A new motion compensated 3 D wavelet transform (MC 3DWT) video coding scheme is presented in this paper. The new coding scheme has a good performance in average PSNR, compression ratio and visual quality of reconstructions compared with the existing 3 D wavelet transform (3DWT) coding methods and motion compensated 2 D wavelet transform (MC WT) coding method. The new MC 3DWT coding scheme is suitable for very low bit rate video coding.

天山中段2次6级地震前钻孔应变高频异常分析

2014年以来,天山中段分量钻孔应变仪空前增多,这些高采样率的应变观测资料蕴含着丰富的构造信息。如何从高采样率观测资料中提取有效的前兆异常信息,是分析研究人员亟待解决的问题。文章通过对天山中段分量钻孔应变观测数据进行S变换和超限率分析发现,在天山中段2次6级地震前有5套应变资料出现高频信息异常。这些异常均在震前出现,随后达到峰值,临震前或地震后衰减,其中短周期异常信号主要集中在10~720 min频段,且S变换与超限率分析结果具有很好的同步性。结合精河地震震源区及附近的GPS分析结果,发现高频异常信息的分布与该地区地壳运动场具有很好的一致性,进一步验证了高频信息异常的可信度。

高比例分布式电源配电网中低压柔性互联协调规划

柔性互联技术是解决高比例分布式电源(distributed generation,DG)配电网面临诸多问题的有效手段之一。提出了一种基于多层优化的配电网中压与低压柔性互联协调规划方法。首先,建立基于电力电子柔性互联设备(flexible interconnected devices,FID)的中低压柔性互联配电网潮流模型。然后,构建三层协调规划模型,上层以低压FID年运行成本及台区变压器负载率的年方差最小为目标,中层以中压FID年运行成本及从上级电网年购电成本最小为目标,分别决策低压和中压FID的安装位置与容量,下层以各场景的从上级电网购电成本最小为目标优化系统运行,并采用自适应粒子群优化和二阶锥规划相结合的混合算法求解。最后,采用含高比例DG的IEEE 33节点配电网进行算例分析,通过柔性互联规划系统的年综合运行成本降低了19.01%,台区变压器负载率的年方差减少了82.59%,验证了所提规划模型的有效性。

盾构隧道衬砌结构偏心破坏转化临界锈蚀率预测

盾构隧道管片中的钢筋锈蚀会对结构的承载性能和破坏形态产生重要影响。一般盾构隧道结构多呈现小偏心受压状态,当钢筋锈蚀发展到一定程度时会出现小偏心向大偏心受力状态的转变,导致结构承载力下降、危及隧道运营安全。基于盾构隧道衬砌结构压弯受荷特点,设计小偏心加载的锈蚀试验柱,等效地模拟隧道衬砌的实际受力状态,分析不同锈蚀程度下试验柱跨中应变、极限承载力及裂缝的全过程演变。随锈蚀程度加重,试验柱承载力、混凝土应变、受压区高度下降速度逐渐加快,最大锈蚀率达到68.32%时,承载力最大降幅达到53.23%。试验发现高锈蚀程度(η≥46.25%)试验柱由小偏心破坏转化为大偏心破坏的现象。基于受弯构件正截面承载力理论分析,提出隧道衬砌结构由小偏心向大偏心破坏转化的临界锈蚀率理论计算方法,通过设计有限元计算流程验证了该方法的正确性。研究结果可为盾构隧道衬砌结构耐久性设计和安全评价提供理论支撑。

企业数字化转型对劳动收入份额的影响

数字化转型作为企业未来发展的新动能,其是否能够提高企业劳动收入份额,优化内部收入分配格局仍存在争议。为厘清二者之间的作用关系,需要在从理论上廓清数字化转型影响企业劳动收入份额的经济逻辑的基础上,利用2012—2020年中国沪深A股上市公司数据进行实证检验。研究发现:数字化转型从整体上提升了企业劳动收入份额,实现了“分好蛋糕”的目标;数字化转型通过工资率和劳动生产率影响劳动收入份额,且对工资率的影响大于对劳动生产率的影响,从而产生数字化转型提高企业劳动收入份额的净效应;数字化转型能够提高企业增加值,实现“做大蛋糕”的目标;与劳动密集型企业相比,资本技术密集型企业的数字化转型对劳动收入份额的提升作用更大;与非国有上市公司相比,国有上市公司的数字化转型对劳动收入份额的影响程度有所下降,主要原因在于国有企业对社会责任的特殊承担。通过揭示数字化转型影响劳动收入份额的内在机理,可以为二者之间作用关系的争议提供微观层面的实证依据,也为数字经济背景下企业如何兼顾效率与公平,实现共同富裕提供有益的政策启示。