This paper first calculates numerically the Symmetric Information Rate (SIR) of Cotinuous Phase Modulation (CPM) schemes over Additive White Gaussian Noise (AWGN) channel, modeling CPM and channel as a Memory-less Mod...This paper first calculates numerically the Symmetric Information Rate (SIR) of Cotinuous Phase Modulation (CPM) schemes over Additive White Gaussian Noise (AWGN) channel, modeling CPM and channel as a Memory-less Modulator (MM) plus a Markov Finite State Channel (FSMC), then proposes an optimal detector, which is of BCJR based Decision Feedback Detector (DFD) but non-iterative. It can achieve the SIR as the sequence length approaches infinity while the complexity is extremely low. Finally, both theoretic proof and numerical simulation are performed to show the op- timality. Simulation results show that it nearly achieves the theoretic bound and outperforms the Viterbi Detector (VD) with 2dB in low Eb/N0.展开更多
目的研究全段食管癌调强放射治疗计划设计中7野对称式布野与8野对称式布野的靶区及危及器官剂量学特点,为全段食管癌放射治疗患者的计划设计提供一定的参考。方法选择15例全段食管癌放射治疗患者,其中男性8例,女性7例;年龄45~84岁,平均...目的研究全段食管癌调强放射治疗计划设计中7野对称式布野与8野对称式布野的靶区及危及器官剂量学特点,为全段食管癌放射治疗患者的计划设计提供一定的参考。方法选择15例全段食管癌放射治疗患者,其中男性8例,女性7例;年龄45~84岁,平均年龄62.5岁;病灶直径(2.8±1.3)cm;病灶长度(14.6±3.7)cm。采用Eclipse计划系统,全组处方剂量均为50 Gy,以95%靶区体积达到100%处方剂量为基准,剂量体积直方图(DVH)比较7野对称式布野与8野对称式布野计划设计方法的主要危及器官的受量。结果靶区均匀性指数(HI),7野对称式布野与8野对称式布野差异无统计学意义(0.55±0.01 vs 0.56±0.01。t=-2.092,P>0.05)。通过比较,全段食管癌调强放射治疗8野对称式布野肺部V_(20)、V_(5)低于7野对称式布野计划[(21.56±3.26)%vs(25.72±1.65)%、(59.60±6.02)%vs(60.48±6.40)%],其他器官差异无统计学意义。结论常规全段食管癌调强放射治疗计划中使用8野对称式布野计划设计方法可有效地减少肺部高剂量区体积,从而进一步减少放射性肺炎的发生率。展开更多
We investigate a wavelength-division-multiplexing passive optical network(WDM-PON) with centralized lightwave and direct detection. The system is demonstrated for symmetric 10 Gbit/s differential phase-shift keying(DP...We investigate a wavelength-division-multiplexing passive optical network(WDM-PON) with centralized lightwave and direct detection. The system is demonstrated for symmetric 10 Gbit/s differential phase-shift keying(DPSK) downstream signals and on-off keying(OOK) upstream signals,respectively. A wavelength reused scheme is employed to carry the upstream data by using a reflective semiconductor optical amplifier(RSOA) as an intensity modulator at the optical network unit(ONU). The constant-intensity property of the DPSK modulation format can keep high extinction ratio(ER) of downstream signal and reduce the crosstalk to the upstream signal. The bit error rate(BER) performance of our scheme shows that the proposed 10 Gbit/s symmetric WDM-PON can achieve error free transmission over 25-km-long fiber transmission with low power penalty.展开更多
Matrix rings are prominent in abstract algebra. In this paper we give an overview of the theory of matrix near-rings. A near-ring differs from a ring in that it does not need to be abelian and one of the distributive ...Matrix rings are prominent in abstract algebra. In this paper we give an overview of the theory of matrix near-rings. A near-ring differs from a ring in that it does not need to be abelian and one of the distributive laws does not hold in general. We introduce two ways in which matrix near-rings can be defined and discuss the structure of each. One is as given by Beildeman and the other is as defined by Meldrum. Beildeman defined his matrix near-rings as normal arrays under the operation of matrix multiplication and addition. He showed that we have a matrix near-ring over a near-ring if, and only if, it is a ring. In this case it is not possible to obtain a matrix near-ring from a proper near-ring. Later, in 1986, Meldrum and van der Walt defined matrix near-rings over a near-ring as mappings from the direct sum of n copies of the additive group of the near-ring to itself. In this case it can be shown that a proper near-ring is obtained. We prove several properties, introduce some special matrices and show that a matrix notation can be introduced to make calculations easier, provided that n is small.展开更多
基金Supported by the Key Industrial Research of Zhejiang Province (No. 2006C21009).
文摘This paper first calculates numerically the Symmetric Information Rate (SIR) of Cotinuous Phase Modulation (CPM) schemes over Additive White Gaussian Noise (AWGN) channel, modeling CPM and channel as a Memory-less Modulator (MM) plus a Markov Finite State Channel (FSMC), then proposes an optimal detector, which is of BCJR based Decision Feedback Detector (DFD) but non-iterative. It can achieve the SIR as the sequence length approaches infinity while the complexity is extremely low. Finally, both theoretic proof and numerical simulation are performed to show the op- timality. Simulation results show that it nearly achieves the theoretic bound and outperforms the Viterbi Detector (VD) with 2dB in low Eb/N0.
文摘目的研究全段食管癌调强放射治疗计划设计中7野对称式布野与8野对称式布野的靶区及危及器官剂量学特点,为全段食管癌放射治疗患者的计划设计提供一定的参考。方法选择15例全段食管癌放射治疗患者,其中男性8例,女性7例;年龄45~84岁,平均年龄62.5岁;病灶直径(2.8±1.3)cm;病灶长度(14.6±3.7)cm。采用Eclipse计划系统,全组处方剂量均为50 Gy,以95%靶区体积达到100%处方剂量为基准,剂量体积直方图(DVH)比较7野对称式布野与8野对称式布野计划设计方法的主要危及器官的受量。结果靶区均匀性指数(HI),7野对称式布野与8野对称式布野差异无统计学意义(0.55±0.01 vs 0.56±0.01。t=-2.092,P>0.05)。通过比较,全段食管癌调强放射治疗8野对称式布野肺部V_(20)、V_(5)低于7野对称式布野计划[(21.56±3.26)%vs(25.72±1.65)%、(59.60±6.02)%vs(60.48±6.40)%],其他器官差异无统计学意义。结论常规全段食管癌调强放射治疗计划中使用8野对称式布野计划设计方法可有效地减少肺部高剂量区体积,从而进一步减少放射性肺炎的发生率。
基金the Alexander von Humboldt Foundation for their support
文摘We investigate a wavelength-division-multiplexing passive optical network(WDM-PON) with centralized lightwave and direct detection. The system is demonstrated for symmetric 10 Gbit/s differential phase-shift keying(DPSK) downstream signals and on-off keying(OOK) upstream signals,respectively. A wavelength reused scheme is employed to carry the upstream data by using a reflective semiconductor optical amplifier(RSOA) as an intensity modulator at the optical network unit(ONU). The constant-intensity property of the DPSK modulation format can keep high extinction ratio(ER) of downstream signal and reduce the crosstalk to the upstream signal. The bit error rate(BER) performance of our scheme shows that the proposed 10 Gbit/s symmetric WDM-PON can achieve error free transmission over 25-km-long fiber transmission with low power penalty.
文摘Matrix rings are prominent in abstract algebra. In this paper we give an overview of the theory of matrix near-rings. A near-ring differs from a ring in that it does not need to be abelian and one of the distributive laws does not hold in general. We introduce two ways in which matrix near-rings can be defined and discuss the structure of each. One is as given by Beildeman and the other is as defined by Meldrum. Beildeman defined his matrix near-rings as normal arrays under the operation of matrix multiplication and addition. He showed that we have a matrix near-ring over a near-ring if, and only if, it is a ring. In this case it is not possible to obtain a matrix near-ring from a proper near-ring. Later, in 1986, Meldrum and van der Walt defined matrix near-rings over a near-ring as mappings from the direct sum of n copies of the additive group of the near-ring to itself. In this case it can be shown that a proper near-ring is obtained. We prove several properties, introduce some special matrices and show that a matrix notation can be introduced to make calculations easier, provided that n is small.
