Starch nanoparticles (SNPs) were produced by batch nanoprecipitation (BNP) and continuous techniques such as flash nanoprecipitation (FNP) and microfluidic nanoprecipitation (MNP). Water and absolute ethanol were used as solvent (5) and antisolvent (AS), respectively, while they can be mixed either dmpwise or direct mixing at once. The effects of processing parameters on SNPs properties were investigated including antisolvent/solvent (AS/S) ratio, starch concentration, mixing technique and flow rate. Field emission scanning electronic microscopy (FE-SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectrophotometry were used to characterize the nature of molecular interactions and structure within SNP. The results indicated that BNP can be successfully achieved in a shorter time with a smaller particle size and narrower particle size distribution, even at AS/5 ratio as low as 1:1, using direct mixing at once method than the dropwise technique. Increasing the starch concentration at a fixed AS/5 ratio of 1:1, initially decreased the average particle size from 135 (2.5 mg/mL) to 123 nm (10 mg/mL), and then increased to similar to 430 nm (50 mg/mL). Based on the optimized conditions for BNP, continuous methods (FNP and MNP), were investigated in the commercial prospective for potential scale up processing. Under the same conditions, FNP involving confined impinging jet mixer (CIJM) at an overall flow rate of 60 mL/min, had a uniform spherical shape with particle size of similar to 100 nm, which was superior to all other techniques investigated. Regardless of the techniques used, all SNPs had an amorphous structure with shortrange molecular order.

Starch nanoparticles (SNPs) were prepared for the first time via a combination of ultrasonic-assisted dissolution of starch and subsequent rapid nanoprecipitation. Purified starches from cereal (regular corn and wheat) and pulse (faba bean and field pea) grains that significantly differ in amylose content were used. The effects of starch source, concentration and amylose content as well as the ratio between antisolvent to solvent (i.e., aqueous starch solution) on the SNPs morphological, molecular, and physicochemical properties were investigated. The morphology was evaluated by scanning electron microscopy (SEM) to observe shape and surface details and dynamic light scattering (DLS) to analyze particle size and poly dispersity index (PDI). Molecular properties of the native starch and SNPs were determined by a high-performance size-exclusion chromatography equipped with a multi angle laser light scattering and a differential refractive detector (HPSEC-MALLS-RI). Physicochemical characterization of the SNPs was performed via measuring the crystallinity by X-ray diffraction (XRD), molecular order by Fourier-transform infrared spectroscopy (FTIR), and thermal properties by differential scanning colorimeter (DSC). Results showed that SNPs from all starches were spherical in shape, where pulse SNPs had smaller and more uniform size than cereal SNPs. Across all starch types, the molecular weight of amylopectin and amylose in SNPs was smaller and more uniform than in the respective native starches. Pulse SNPs with higher amylose content showed greater relative crystallinity, enhanced short-range molecular order, and better thermal stability. A schematic diagram has been proposed to explain the variations in SNP size, where amylose-amylopectin ratio plays an important role.

The nutritive value of starch, the major source of dietary energy in pigs, varies depending on its susceptibility for digestion. The botanical origin of starch determines starch structure, and therefore, digestibility. To compare digestibility of starch, fiber, gross energy (GE), crude protein, and amino acid (AA), and to characterize undigested starch of grains in growing pigs, seven ileal-cannulated barrows (initial body weight, 30 kg) were fed six diets containing 96% of one of six test ingredients (three pulse grains: zero-tannin faba bean, green field pea, or mixed-cultivar chickpea; three cereal grains: hulled barley, hard red spring wheat, or hybrid yellow, dent corn), or a N-free diet in a 7 × 7 Latin square at 2.8 × maintenance digestible energy. Grain samples were ground with a hammer mill through a 2.78-mm screen. Amylose content ranged from 29% to 34% for pulse grains and from 22% to 25% for cereal grains. The apparent ileal digestibility (AID) of starch was greater (P < 0.05) in cereal (94% to 97%) than pulse grains (85% to 90%) and was lowest (P < 0.05) in faba bean (85.3%) followed by field pea (87.2%) and chickpea (90.1%). However, apparent total tract digestibility (ATTD) of starch of all tested grains was close to 100%. Apparent hindgut fermentability (AHF, as ATTD - AID) of starch was greater (P < 0.05) in pulse grains (9.9% to 15%) than cereal grains (3.3% to 4.8%). The AHF of total dietary fiber tended to be the greatest (P < 0.10) for corn (43.5%) and lowest for wheat (25.3%). The AHF of GE was greater (P < 0.05) in pulse grains (17% to 20%) than in cereal grains (9% to 11%) and resulted in greater (P < 0.05) digestible energy (DE) contribution from hindgut fermentation for pulse grains than cereal grains (0.9 vs. 0.5 Mcal/kg). Wheat had the greatest standardized ileal digestibility of total AA (90.2%; P < 0.05). Confocal laser scanning microscopy images revealed that 20% to 30% of starch granules of pulse grains were entrapped in protein matrixes. In scanning electron microscopy images, starch granules were larger in faba bean and field pea than cereal grains. Digesta samples revealed pin holes and surface cracks in starch granules of corn and wheat, respectively. In conclusion, hindgut fermentation of starch and fiber was greater in pulse grains than cereal grains resulting in a greater DE value despite lower ileal DE for pulse grain than cereal grains. Defining the digestible and fermentable fractions of starch may enhance the accuracy of equations to predict the net energy value of these feedstuffs.

Starch nanoparticles (SNPs) were produced from pulse (faba bean and field pea) and cereal (corn and wheat) starches by rapid nanoprecipitation under identical conditions. SNP morphological features such as shape and particle size distribution (PSD) were determined by field emission scanning electron microscopy (FE-SEM) and dynamic light scattering (DLS) techniques. Static and dynamic rheological properties of the aqueous SNP suspensions were investigated by rotational and oscillatory rheometry. The SNPs from all starch sources were spherical in shape but varied in their size distribution. The viscosity and viscoelastic behavior of SNP suspensions when determined as a function of shear, frequency and temperature were dependent on starch source and SNP concentration. The SNP suspensions exhibited a viscous liquid-like behavior at low concentrations (i.e., 1% w/v), but an elastic gel-like behavior at high concentrations (i.e., 5% w/v). Interestingly, at a concentration of 5% (w/v), SNP suspensions showed an excellent flow behavior, demonstrating their capacity to instantaneously recover from the applied shear deformation. However, pulse SNPs displayed relatively greater viscosities and a more elastic behavior than cereal SNPs, indicating their potential to form extensive inter-particulate associations. A schematic diagram has been proposed to explain the observed rheological behaviors, predicting inter-particulate network formation at room temperature and the biphasic molecular network formation during heating of aqueous SNP suspensions. A careful selection of starch type and processing conditions, such as temperature and shear conditions, is required to achieve specific desired functionalities for SNP in the food industry.

In this paper, coordinate interleaved orthogonal frequency division multiplexing with index modulation‐ (CI‐OFDM‐IM) based orthogonal cooperative system (OCS) is proposed, where the source activates half of the subcarriers to convey the symbols in the first time slot (TS). The subcarrier activation patterns (SAPs) are also exploited to convey additional information. In the second TS, the relay amplifies and forwards the received signal to the destination, meanwhile, the source activates the remaining half of the subcarriers to convey the new symbols to the destination. Since the source and relay transmit different symbols to the destination on the different subcarriers in the second TS, the mutual interference is avoided at the destination. Compared with the current OFDM based OCS, the proposed CI‐OFDM‐IM‐based OCS can achieve a higher spectral efficiency, since the SAPs are exploited to convey additional information. Furthermore, the CI‐OFDM‐IM‐based OCS can achieve additional power gain for a certain average transmit power, since the power of inactive subcarriers can be reallocated on the active subcarriers. The optimal constellation rotation, in the sense of maximizing the minimum Euclidean distance between the symbols conveyed on a subcarrier over two TSs, is provided to optimize the performance of CI‐OFDM‐IM‐based OCS. Simulation results show that the proposed CI‐OFDM‐IM‐based OCS achieves a better trade‐off between spectral efficiency and bit error ratio performance.

Field pea starch was thermally solubilized in water and subsequently ultrasonicated and then used to produce starch nanoparticles (SNPs) via a rapid nanoprecipitation method with the addition of the antisolvent (AS) ethanol into the starch solution (solvent, S). The spherical shape of SNPs with a small mean particle size was visualized by dynamic light scattering (DLS) and field emission-scanning electron microscopy (FE-SEM), which demonstrated a narrow size distribution (PSD) and good water dispersibility. Processing parameters, such as duration and amplitude of ultrasonication, AS/S ratio, starch concentration, separation and drying techniques, were investigated in relation to their effect on SNPs properties. There is an optimal AS/S ratio (1:1) and starch concentration (10 mg/mL) which gives rise to smaller SNPs with a narrower PSD. The formation of SNPs was found to follow a kinetically controlled nucleation-growth/aggregation mechanism in which amylose molecules formed the initial critical nuclei. The ultrasonication amplitude and separation and drying techniques significantly affected the size and morphology of SNPs. Moderate shear facilitated rapid starch aggregation and SNPs precipitation, enabling easy recovery by centrifugation and subsequent freeze drying. The freeze-dried SNPs were able to be dispersed quickly to form a SNP suspension in Milli-Q water. The dispersed SNPs showed good thermal stability in water and retained their particle characteristics at a temperature range of 25-60 degrees C. Further research exploring the potential of these SNPs as nutraceutical carriers for applications in both health and nutrition industries is warranted.

针对转发放大(Amplify-and-Forward,AF)模式下的双路径中继网络,为了降低训练序列设计相互约束关系的复杂度,并提升系统误码性能,本文提出了一种基于预编码的信号传输方案.新方案采用一对相互正交的预编码矩阵,分别在两个中继处对信号进行预编码,在目的点右乘相应的解码矩阵将两路叠加信号分离.新方案能够将两路信号完全分离从而使原本需要考虑三处训练序列设计的问题转化为两处,简化了训练序列设计复杂度.由于预编码方案能够在目的点压缩噪声功率,并且避免两路中继信号的互相干扰,单路径误码性能和双路径分集合并误码性能都得到提升.仿真结果验证了新方案的有效性.

To deal with problems of uncertain modulations and multiple pulse widths in pulse waveforms (PWs) during the identifying procedure, a novel specific emitter identification (SEI) method based on PW images (PWIs) and convolutional neural network is proposed. In the method, a more accurate signal model is built with considering the rising, steady and falling part of the whole PW based on actual radar pulse signals. PWI achieves transforming time-domain waveforms to 2D binary images as an SEI analysis feature. To match the PWI feature, a convolutional neural network with the small convolutional kernel is designed to extract the subtle features and finish the supervised training. By tuning the parameters of the convolutional neural network, it completes a balance of consuming time and identifying accuracy. Simulations and experiments indicate that the proposed method outperforms the existed methods on identifying radar individuals with uncertain modulations and multiple pulse widths in the intercepted pulse signals.

Coded Orthogonal frequency division multiplexing with index modulation (OFDM-IM) has been proposed, where channel coding and soft decision are employed to exploit the multipath diversity for the information conveyed by the constellation symbols. However, the performance of coded OFDM-IM is dependent on the detection performance of subcarrier activation pattern (SAP) and the diversity order of the SAPs requires further investigation. In this paper, a lower-bound of LLR detector is derived to show that the maximum achievable diversity order is the minimum Hamming distance between the SAPs for the LLR detector. Based on the analyses, iterative detection is proposed to improve the performance of coded OFDM-IM, where information-assisted LLR detector is proposed to improve the detection performance of SAP by using the soft information of the constellation symbols. Simulation results are provided to corroborate the diversity analyses and show the advantage of the coded OFDM-IM with iterative detection.

With the electromagnetic environment becoming more and more complex and the analysis demand of the radar emitter intropulse signal presenting more and more urgent, a modified method of the radar emitter intrapulse signal blind sorting under wavelet denoising is proposed. This study aims to improve the weak adaptability to the noise of the fast independent component analysis (FastICA) algorithm and its blind source separating performance. In this method, a pre-processing of noise based on the modified wavelet denoising is added. Then the FastICA algorithm is used to sort the unknown radar emitter intrapulse signal for the next intrapulse signal analysis. Simulations and analysis indicate that the modified method improves the signal to noise ratio of the received intermediate signals and the blind sorting performance.

A low complexity channel estimation scheme using data-dependent superimposed training (DDST) is proposed in this paper, where the pilots are inserted in more than one block, rather than the single block of the original DDST. Comparing with the original DDST (which improves the performance of channel estimation at the cost of huge computational overheads), the proposed DDST scheme improves the performance of channel estimation with only a slight increase in the consumption of computation resources. The optimal precoder is designed to minimize the data distortion caused by the rank-deficient precoding. The optimal pilots and placement are also provided to improve the performance of channel estimation. In addition, the impact of power allocation between the data and pilots on symbol detection is analyzed, the optimal power allocation scheme is derived to maximize the effective signal-to-noise ratio at the receiver. Simulation results are presented to show the computational advantage of the proposed scheme, and the advantages of the optimal pilots and power allocation scheme.

Orthogonal frequency-division multiplexing with index modulation (OFDM-IM) is an emerging and promising multicarrier transmission technique; however, frequency diversity achievement requires further investigation for the OFDM-IM. In this paper, the linear constellation precoded OFDM with interleaved subcarrier index modulation (LCP-OFDM-ISIM) is proposed, where a unitary matrix is employed to spread the constellation symbols over all the active subcarriers of the block and the binary constant weight code (BCWC) is utilized as the subcarrier activation pattern (SAP). At the receiver, energy detection is employed to initialize the SAP estimation, and then, the cascaded feedback detection is proposed to refine the detection performance by passing the detection results between the symbol detection and the data-assisted SAP detection. For L-taps channel, conditioned on the BCWC with the minimum Hamming distance of d, energy detection can achieve the diversity order of min(d/2, r), and a closed-form expression is derived for the energy detection. It is shown, via the pair-wise error probability, that the data-assisted SAP detection included in cascaded feedback detection can achieve the diversity order of min(d, L). The simulation results are provided to show the superiority of the LCP-OFDM-ISIM over the benchmarks.

针对转发放大(amplify-and-forward,AF)模式下双路径连续中继(two-path successive relay,TPSR)存在的中继间干扰(inter-relay interference,IRl)问题,提出了新颖的基于行空间映射的中继干扰消除方案.新方案对源节点信号进行交替行空间预编码,从而将接收期望信号与IRI信号映射到不依赖信道的正交子空间,在未知信道下实现IRI和累计噪声的完美消除,从而消除非理想信道估计带来的剩余自干扰和累积噪声对TPSR性能的影响.在这基础上,推导不同信道估计误差下系统平均误比特率(bit error ratio,BER)的闭合表达式和近似表达式,并通过仿真验证理论推导的正确性.通过对比该方案与传统基于信道估计的干扰消除方案在不同估计误差下的检测性能,表明新方案能够完全消除IRI和累积噪声,有效提升连续中继网络性能.

The current orthogonal cooperative system (OCS) achieves diversity through the use of relays and the consumption of an additional time slot (TS). To guarantee the orthogonality of the received signal and avoid the mutual interference at the destination, the source has to be mute in the second TS. Consequently, the spectral efficiency (SE) is halved. In this paper, linear constellation precoded orthogonal frequency division multiplexing with index modulation (LCP-OFDM-IM) based OCS is proposed, where the source activates the complementary subcarriers to convey the symbols over two TSs. Hence the source can consecutively transmit information to the destination without the mutual interference. Compared with the current OFDM based OCS, the LCP-OFDM-IM based OCS can achieve a higher SE, since the subcarrier activation patterns (SAPs) can be exploited to convey additional information. Furthermore, the optimal precoder, in the sense of maximizing the minimum Euclidean distance of the symbols conveyed on each subcarrier over two TSs, is provided. Simulation results show the superiority of the LCP-OFDM-IM based OCS over the current OFDM based OCS.

双向中继网络(two-way relay network,TWRN)在提高频谱效率的同时会引入额外的自干扰,针对放大转发模式下的自干扰抵消问题,从消除非理想信道估计带来的剩余自干扰着手,提出一种基于正交预编码的盲干扰抵消方案。新方案通过对端节点信号进行"右乘"正交预编码,将期望目标信号与自干扰信号映射到不依赖于信道状态信息的正交子空间,实现未知信道状态下自干扰抵消和期望信号分离,从而消除非理想信道估计带来的剩余自干扰对TWRN性能的影响,提高了系统的鲁棒性。在此基础上,通过推导平均误比特率(bit error rate,BER)的闭合表达式和渐进表达式,分析不同方案下信道估计误差对平均BER的影响,并通过仿真对比验证了理论推导的正确性。

针对放大转发(Amplify-and-Forward,AF)模式下的菱形中继网络,为了高效获取级联和单跳链路信道状态信息(Channel State Information,CSI),本文提出基于叠加训练的信道估计方案,以消除多址接入干扰和训练间互干扰为目标,进行最优的多训练序列设计.新方案将中继训练叠加到源训练序列上,通过对中继识别符号以及中继训练组进行联合优化设计,设计了一种基于频域循环移位的正交扩展序列组生成算法.为了消除非高斯复合噪声对单跳信道估计造成的严重干扰,进而提出中继噪声消除算法.该方案能够准确获取CSI,在端节点实现分集合并,有效提高符号检测性能.仿真实验对比了同类型的信道估计方案,分析验证了方案的有效性.

In this letter, we deal with the problem of individual channel estimation in amplify-and-forward (AF) relaying systems. A novel superimposed training (ST) scheme is proposed where the relay superimposes its own training sequence directly on top of the received data signal without bandwidth expansion. As a result, the training sequences from the source and relay nodes are independent of each other and can be viewed as a time-multiplexed (TM) mode in the proposed scheme, thus making it more flexible and robust in relay-training design. To remove the data-induced interference and relaying-propagated noise during channel estimation, a modified ST scheme is designed by discarding some relaying data to accommodate the relay-training sequence. Simulation results are presented to assess the performances of the proposed scheme and to obtain the optimal power allocation.

For the OFDM-based Amplify-and-Forward cooperative system, a novel relay-superimposed pilot strategy is proposed, where the source pilot symbols are frequency division multiplexed to estimate the cascaded channel while relay pilot sequence is superimposed onto the top of the cooperative data stream for second-hop channel estimation. This method avoids the loss of data rate for additional pilot subcarriers but results in the interference of unknown cooperative data. To remove the interference of cooperative data during the estimation of second-hop channel, the Cooperative Interference Cancelation scheme assisted by cooperative data from direct link is proposed. We derive the approximated lower bound for the MSE of second-hop channel estimation. Simulation results are presented to validate the performance of the proposed schemes.

In an amplify-and-forward (AF) cooperative relay network,the combined training scheme is proposed to acquire channel state information (CSI) of different links.The combined training mode consists time-division multiplexing (TM) training and superimposed training (ST),where the TM training is employed at source node to estimate the cascaded channel (S-R-D) while the relay training sequence is added on top of the information-beating received signal to estimate the second-hop channel (R-D).In order to improve the estimation performance of R-D link,a novel cooperative interference suppression (CIS) scheme is proposed to remove cooperative data interference using detected symbols of S-D links.The new scheme employs combined training mode to make the individual channel and cascaded channel estimated independently,decreasing the complexity of training sequence design.Simulation results are presented to validate the performance of the proposed schemes.

In this letter, we consider the inter-relay interference (IRI) problem for amplify-and-forward (AF) two-path successive relay networks. To reduce processing burden for IRI cancelation at the relay nodes, a novel precoding-based interference cancelation scheme based on row-space mapping is proposed, where a pair of orthogonal precoding matrices is alternately utilized to project the source data onto the null space of the received data that is independent of channel state information (CSI). By designing a combined decoding and re-encoding scheme, both the IRI signal and accumulated noise are perfectly suppressed at the relay nodes. Simulation results show that the proposed scheme is significantly better than the channel estimate based interference cancelation schemes.