科研成果 by Type: Conference Paper

This paper provides the first piece of empirical evidence regarding the impact of health cost risk on individuals' annuitization decisions. We find that health cost risk increases the probability of individuals' pension participation but decreases the amount of pension contributions. We show that the substitution effect of informal insurance on pensions leads to these seemingly contradictory results. The impact of health cost risk on pension participation and contributions is negative and consistent with the mainstream theory after accounting for the effect of informal insurance. The substitution effect of informal insurance on pensions is stronger, and thus mitigates the impact of health cost risk more pronounced for households that have better-educated children, lower incomes, and more informal social networks and in regions that have a higher male–female ratio, that have higher mobility, or are less developed; but this substitution effect does not differ depending on their children's gender. This study improves our understanding of the relationship between health cost risk and individuals' annuitization decisions as well as the role of informal insurance in this relationship.

A few colonies in the Latin West (Augusta Emerita, Johnston 2017: 56-57 fn. 202-203; Abascal 2002: 284) and the Greek East (e.g. Philippi AE 1932, 21; briefly Samos IG XII,6 1:187 l. 8-11) used the annus coloniae, the year when the colony was founded, as their standard time-reckoning formula on inscriptions and perhaps other media as well. The list may include the Roman colony of Sinope, which coin issues carried legends such as C(olonia) F(elix) I(ulia) an(no) followed by (and later on simply with) Latin numerals (e.g. RPC I 2110, II 715). Curiously, since the 17th century, numismatists have observed two epochs on Sinope’s Roman period issues (e.g. Hardouin 1689: 140). There was the epoch of 45 BCE, likely the annus coloniae (e.g. RPC III 1229), as it coincided with reports of a Caesarian colony (Strab. 12.3.11). Then there was the epoch of 70 BCE (e.g. RPC VI 6501), seemingly replacing the earlier epoch, but only from the early third century onwards (Kubitschek 1908: 68-71; Magie 1950: 342 no. 42).  Changing epochs was not a rare phenomenon in Anatolia, but known examples changed an earlier epoch for a later one, apparently to adapt to new circumstances, such as an imperial victory or visit (Leschhorn 1993: 439-541), and count years from a new beginning. Sinope, however, changed the epoch that was supposedly linked to the year of its colonial foundation to an earlier epoch that coincided with Lucullus’ “liberation” of Sinope from Mithridatid control. This suggests that Sinope was adapting to new circumstances that required the adaptation of an historical epoch. It is not the beginning per se, but a recaliberation of municipal history. While historical developments of Roman Sinope is not well documented in extant literary sources, and epigraphic evidence is scarce, this paper wishes to take two approaches to assess the problem of Sinope’s changing epochs. The first approach is to consider Sinope’s time-reckoning tradition. The era system that was prevalent in northern Anatolia and elsewhere during the first three centuries CE had a strong Hellenistic tradition. In this view, there may be more nuance – 45 BCE can be the annus coloniae, but it was reflecting a recent change in the city’s history, not an overhaul of the city’s established time-reckoning system, perhaps based on the Seleucid era (found on ceramic stamps, Saprykin & Fedoseev 1999: 135-143). This approach removes the Roman symbolism attached to the 45 BCE, and opens up additional possibilities for interpretation. The second approach considers the epoch of 70 BCE regionally. This epoch was primarily used at Amastris, but also attested at Abonuteichos. Both cities were described by Roman authors as prosperous in their own ways (e.g. Luc. Alex. 9, 25; Plin. Ep. 10.98). Both cities also began to issue 3 to 4 units of local bronze coinage from the reign of Trajan onwards, including the 6-assaria, associated with economic prosperity (Zajac 2023: 30-32, Tab. 1a). Epigraphic and numismatic evidence further suggest that Amastrians were mobile across the Black Sea and the Aegean, some even serving as koinon officials of Bithynian and other regional koina (Marek 2003: 63-67). There is the possibility that Sinope changed its epoch to adhere to regional time-reckoning norms set by more dominant peers. Since the 17th century, numismatists have observed two epochs on Sinope’s Roman period coin issues (e.g. Hardouin 1689: 140). There was the epoch of 45 BCE, perhaps the annus coloniae (e.g. RPC III 1229; cf. Augusta Emerita, Johnston 2017: 56-57 fn. 202-203; Abascal 2002: 284; Philippi AE 1932, 21; briefly Samos IG XII,6 1:187 l. 8-11), as it coincided with reports of a Caesarian colony (Strab. 12.3.11). Then there was the epoch of 70 BCE (e.g. RPC VI 6501), seemingly replacing the earlier epoch, but only from the early third century onwards (Kubitschek 1908: 68-71; Magie 1950: 342 no. 42). Neither changing epochs or the use of many epochs were rare phenomena. That said, known examples show cities replacing old epochs with those that commemorate new events and circumstances (Leschhorn 1993: 439-541). It is then odd for Sinope to abandon the epoch commemorating its colonial foundation in favor of an epoch 25 years earlier. Why? Leschhorn gave two potential scenarios: perhaps 70 BCE was the outcome a pro-Severan party defeating the old guard, or there was a “Gräzisierung" movement under which Sinope opted for a symbolically more acceptable epoch (Leschhorn 1993: 162), but these suggestions are limited by lack of evidence. This paper reassesses Sinope’s changing epochs with two approaches. First is a reframing of the Leschhorn’s assumed constitutional symbolism attached to the epoch of 45 BCE that leads to factionalism, and the “Roman” nature of Sinope’s so-called Kolonieära in Leschhorn’s alternative “Gräzisierung” thesis. The question asked here is whether Sinope had an established era system in place as part of its Hellenistic past. Sinope likely used the Pontic era while under Mithridatid control (Leschhorn 1993: 150). Recent discussions of stamped amphorae further indicates that the Seleucid era system was likely present if not also used at Sinope (Saprykin & Fedoseev 1999: 135-143). Further, we now have ceramic tiles time-stamped with a formula such as "s(aeculo) S(inopensis) (colonia) i(nducta) an(no) IV" (Fedoseev 2019: 16-17). If Fedoseev’s reading of the time-stamp is correct, we may consider the possibility that the saeculum Sinopensis was a system that could have accommodated multiple epochs, and the phenomenon in question was a symptom of an entrenched but adaptative time-reckoning mechanism at work. The second approach considers the epoch of 70 BCE regionally. This epoch was primarily used at Amastris, but also attested at Abonuteichos. Both cities were described by Roman authors as prosperous in their own ways (e.g. Luc. Alex. 9, 25; Plin. Ep. 10.98). Both cities also began to issue 3 to 4 units of local bronze coinage from the reign of Trajan onwards, including the 6-assaria, associated with economic prosperity (Zajac 2023: 30-32, Tab. 1a). Epigraphic and numismatic evidence further suggest that Amastrians were mobile across the Black Sea and the Aegean, some even serving as koinon officials of Bithynian and other regional koina (Marek 2003: 63-67). There is the possibility that Sinope changed its epoch to adhere to regional time-reckoning norms set by more dominant peers.

Automotive audio systems often face sub-optimal sound quality due to the intricate acoustic properties of car cabins. Acoustic channel equalization methods are generally employed to improve sound reproduction quality in such environments. In this paper, we propose an acoustic channel equalization method using convex optimization in the modal domain. The modal domain representation is used to model the whole sound field to be equalized. Besides integrating it into the convex formulation of the acoustic channel reshaping problem, to further control the prering artifacts, the temporal window function modified according to the backward masking effect of the human auditory system is used during equalizer design. Objective and subjective experiments in a real automotive cabin proved that the proposed method enhances spatial robustness and avoids the audible prering artifacts.

The multiple-channel[1] sound source enhancement methods have made a great progress in recent years, especially when combined with the learning-based algorithms. However, the performance of these techniques is limited by the completeness of the training dataset, which may degrade in mismatched environments. In this paper, we propose a reconstruction Model based Self-supervised Learning (RMSL) method for sound source enhancement. A reconstruction module is used to integrate the estimated target signal and noise components to regenerate the multi-channel mixed signals, and it is connected with a separating model to form a closed loop.In this case, the optimization of the separation model can be achieved by continuously iterating the separation-reconstruction process. We use the separation error, the reconstruction error, and the signal-noise independence error as lossfunctions in the self-supervised learning process. This method is applied to the state-of-the-art sound source separation model (ADL-MVDR) and evaluated under different scenarios. Experimental results demonstrate that the proposed method can improve the performance of ADL-MVDR algorithm under different number of sound sources, bringing about 0.5 dB to 1 dB Si-SNR gain, while maintaining good clarity and intelligibility in practical application.

Deep neural networks can be employed for estimating the direction of arrival (DOA) of individual sound sources from audio signals. Existing methods mostly focus on estimating the DOA of each source on individual frames, without utilizing the motion information of the sources. This paper proposes a method for estimating trajectories of sources, leveraging the differential of trajectories across different time scales. Additionally, a neural network is employed for enhancing the trajectories wrongly estimated especially for sound sources with low-energy. Experimental evaluations conducted on simulated dataset validate that the proposed method achieves more precise localization and tracking performance and encounters less interference when the sound source energy is low.