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《International Journal of Hydrogen Energy》2023,48(54):20613-20632
Research focused on reusing lignocellulosic waste has been gaining ground, both for the purpose of obtaining energy from renewable sources, as well as for reducing feedstock costs and preventing environmental pollution. Despite being currently evaluated as a promising feedstock, large-scale application of lignocellulosic waste to obtain bioenergy is still scarce. One of the obstacles in terms of reusing it is its recalcitrant composition, often requiring pretreatment applications to break its fibers, increasing its bioavailability. In addition to the type of substrate, there are many operational parameters that may affect the process efficiency, including the type of reactor, temperature, pH, inoculum source, among others. Considering this, it is interesting to consider using statistical tools instead of “one-factor-at-a-time” methods for simultaneous optimization of these variables to increase the production of value-added compounds, such as Plackett-Burman screening design and Central Composite Rotational Design. In this context, this review aimed at compiling data regarding obtaining value-added compounds, focusing on bio-H2 and bio-CH4, from different lignocellulosic waste, such as sugarcane bagasse, citrus peel waste, coffee and cereal husks, brewer's spent grain, cocoa processing waste, sawdust, among others, considering the main operational parameters involved (temperature, pH, inoculum) and the type of pretreatment applied (physical, chemical and/or biological). The results described here may support future research on reusing residual lignocellulosic waste, in addition to elucidating the importance of different operational parameters to convert this waste into H2 and/or CH4. 相似文献
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Pretreatments are crucial to achieve efficient conversion of lignocellulosic biomass to soluble sugars. In this light, switchgrass was subjected to 13 pretreatments including steam explosion alone (195 °C for 5, 10 and 15 min) and after impregnation with the following catalysts: Ca(OH)2 at low (0.4%) and high (0.7%) concentration; Ca(OH)2 at high concentration and higher temperature (205 °C for 5, 10 and 15 min); H2SO4 (0.2% at 195 °C for 10 min) as reference acid catalyst before steam explosion. Enzymatic hydrolysis was carried out to assess pretreatment efficiency in both solid and liquid fraction. Thereafter, in selected pretreatments the solid fraction was subjected to simultaneous saccharification and fermentation (SSF), while the liquid fraction underwent anaerobic digestion (AD). Lignin removal was lowest (12%) and highest (35%) with steam alone and 0.7% lime, respectively. In general, higher cellulose degradation and lower hemicellulose hydrolysis were observed in this study compared to others, depending on lower biomass hydration during steam explosion. Mild lime addition (0.4% at 195 °C) enhanced ethanol in SSF (+28% than steam alone), while H2SO4 boosted methane in AD (+110%). However, methane represented a lesser component in combined energy yield (ethanol, methane and energy content of residual solid). Mild lime addition was also shown less aggressive and secured more residual solid after SSF, resulting in higher energy yield per unit raw biomass. Decreased water consumption, avoidance of toxic compounds in downstream effluents, and post process recovery of Ca(OH)2 as CaCO3 represent further advantages of pretreatments involving mild lime addition before steam explosion. 相似文献
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MIL-STD-1750A指令集是星载弹载计算机常用指令集之一,为实现该类指令集CPU+FPGA的通用性验证,实现安全性、强度、单粒子翻转等异常测试,满足测试覆盖率要求,保证星载弹载计算机系统可靠性,提出了一种CPU+FPGA的仿真模型搭建方法,利用如中断和故障处理机制的实现、浮点运算单元设计方式、异常注入机制设计以及图形控制界面等关键技术,实现了一种精简1750A仿真软核。实验证明,利用该仿真软核设计的CPU+FPGA的仿真模型平台,可极大提高1750系列CPU相关接口的FPGA产品的验证效率和可靠性,也为后续星载弹载软件的测试提供了一套故障注入方便、故障定位清晰的测试平台。 相似文献
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该文重点论述了基于MIL-STD-1750A标准的嵌入式微处理器浮点执行部件EMFPU(EmbeddedFloatingPointUnit)的CPLD实现。详细介绍了FLEX10KE器件的结构特点,EMFPU的设计,以及在AlteraCPLD可编程器件上的实现,并给出了实现的结果。 相似文献
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Twelve maize genotypes, were agronomically evaluated and their stover hydrothermally pretreated in a temperature range of 210–225 °C to assess the effects of genotype and pretreatment severity on stover recalcitrance toward bioethanol conversion. Maize genotypes exhibited significant variation for biomass yield and all agronomic evaluated, while among all cell wall constituents measured in the unpretreated stover, only ash content showed differences among genotypes. The pretreatment severities assayed impacted most stover compositional traits, and the glucose recovered after enzymatic hydrolysis displayed a similar profile among genotypes with similar genetic background. Harsher pretreatment conditions maximized the potential cellulosic bioethanol production (208–239 L/t), while the mildest maximized the bioethanol from the hemicellulosic hydrolysates (137–175 L/t). Consequently, when both pentose and hexose sugars were considered, the total potential bioethanol produced at the lowest and highest pretreatment temperatures was similar in all genotypes (292–358 L/t), indicating that the lowest temperature (210 °C) was the optimal among all assayed. Importantly, the ranking of genotypes for bioethanol yield (L/ha) closely resembled the ranking for stover yield (t/ha), indicating that breeding for biomass yield would increase the bioethanol production per hectare regardless of the manufacturing process. Similarly, the genetic regulation of corn stover moisture is possible and relevant for efficient energy production as biomass moisture has a potential impact on stover transportation, storage and processing requirements. Overall, these results indicate that local landrace populations are important genetic resources to improve cultivated crops, and that simultaneous breeding for production of grain and stover bioethanol is possible in corn. 相似文献
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Karsten Trott 《电子产品世界》2010,17(3):23-26
有许多算法可以转化为纯硬件来加速处理器,诸如平均标准偏差算法、给定时间内创建最小值或最大值、滤波器以及FFT等。不过,诸如位反转等一些不常见的算法可采用合适的硬件加速器也能移植到硬件上。本文以赛灵思的MicroBlaze为例,探讨了在FPGA上采用此种硬件加速方法,使系统性能可超过标准处理器、控制器甚至DSP。 相似文献
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在FPU的设计中,乘法运算电路是设计高精度高速度的乘法电路的重要部分,对提高整个FPU的性能具有重要的意义。通过对浮点处理单元(FPU)的体系结构的分析,比较了速度和规模分析并行通用乘法器之间的优缺点,结合FPU整体设计以及兼顾速度和规模,提出一种不同于通用乘法器设计的方法。该方法采用指数、尾数两条数据通道,用基-4的Booth算法和桶形移位寄存器,通过迭代完成乘法计算,并用VerilogHDL语言编写模块,用Modelsim进行仿真验证。这种方法速度快、占用硬件资源少,适于在FPU中实现,也可以做为一个独立的乘法器使用。 相似文献