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Focusing on the high peak-to-average power ratio （PAPR） problem in orthogonal frequency division multiplexing （OFDM） systems， a generalized hybrid of rayleigh and sine distribution based nonlinear companding algorithm for PAPR reduction in OFDM systems was provided.For the proposed algorithm， signal samples with small amplitudes remain unchanged.For the signal samples with large amplitudes， their probability density function were changed from rayleigh distribution to sine-based distribution.The proposed algorithm can effectively reduce the PAPR， and at the same time， maintain the bit error rate performance and power spectral density performance.Simulation results indicate that with the same PAPR performance， compared with referred companding schemes， the proposed algorithm has lower bit error rate and out of band radiation.

Author affiliations *Corresponding authors Sulfur isotopes serve as critical tracers for understanding the material sources and cycling in earth science. The in situ sulfur isotope ratio analysis by laser ablation multiple-collector inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS) has been a proven important technique, yet the precision and accuracy of measurement are limited by matrix-matched reference materials. In this study, we investigated three new potential reference materials (pyrite NWU-Py, gypsum NWU-Gy and arsenopyrite NWU-Apy) for sulfur isotope ratio analysis by LA-MC-ICP-MS. The ultra-fine powders of pyrite, gypsum and arsenopyrite were synthesized into a solid block using the fast-hot-pressing sintering method (FHP). The reliability of these reference materials was evaluated by large quantities of sulfur isotope measurements by LA-MC-ICP-MS, with mean δ34S values of 3.48 ± 0.26‰ (2SD, n = 787) for NWU-Py, 18.19 ± 0.32‰ (2SD, n = 290) for NWU-Gy, and -0.19 ± 0.32‰ (2SD, n = 383) for NWU-Apy, which are highly consistent with those obtained from isotope ratio mass spectrometry (IRMS). Furthermore, the F-testing and H-index indicate that the three materials have excellent homogeneity of sulfur isotope compositions. Therefore, NWU-Py, NWU-Gy, and NWU-Apy can serve as bracketing matrix-matched reference materials for in situ sulfur isotope measurement by LA-MC-ICP-MS. [ABSTRACT FROM AUTHOR]

This study developed a new method for in situ measurement of stable Mo isotope ratio using femtosecond laser ablation connected to a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS). We assessed how laser fluence, laser repetition rate, and signal intensity impact Mo isotope mass fractionation, using synthetic molybdenite Mo-H8 as the reference material. Findings reveal that the laser repetition rate has negligible impact on Mo isotope fractionation, while signal intensity and laser fluence slightly influence the precision of d98Mo. Significant signal intensity disparities between samples and reference materials can markedly affect the results of Mo isotopes. We analyzed natural molybdenite samples from various deposits in China with this new method, with the optimal laser parameters including a repetition rate of 10 Hz, a spot size of 20 mm, and a fluence of 1 J cm-2. The d98MoNIST SRM 3134 values for nine natural samples (GD-1, GD-2, YN-1, YN-2, YN-3, SX-1, SX-2, SX-3, and GX-1) align with those obtained by solution nebulization MC-ICP-MS within analytical uncertainty, demonstrating the accuracy of this new in situ Mo isotope analytical method. This new technique offers a reliable alternative to solution nebulization MC-ICP-MS in bulk analysis, enabling precise detection of Mo isotope ratio variations at a finer scale, which provides valuable insights into mineralization processes. [ABSTRACT FROM AUTHOR]