共查询到20条相似文献,搜索用时 31 毫秒
1.
A. Suryachandra Rao Y. Sadhuram V. V. Gopala Krishna 《Journal of Earth System Science》1995,104(4):607-611
We estimate, from the moisture budget the bulk aerodynamic coefficient for latent heat flux (C
e) during the monsoon season over the central Arabian Sea. The average value ofC
eunder active monsoon conditions was found to be 2.25 × 10−3 which is nearly 60% higher than those previously used. 相似文献
2.
Anomalous electric field changes and high flash rate beneath a thunderstorm in northeast India 总被引:1,自引:0,他引:1
In spite of many experimental and theoretical studies the relationships between storm dynamics, severe weather, and lightning
activity have been least understood. Measurements of electric field made under a severe thunderstorm at a northeastern Indian
station, Guwahati, India are reported. Lightning flash rate increases drastically to about 84 flashes per minute (fpm) during
the active stage which lasted for about 7 minutes, from about 15 flashes per minute during the initial phase of thunderstorm.
Sudden increase in lightning flash rate (‘lightning jump’) of about 65 fpm/min is also observed in the beginning of the active
stage. The dissipating stage is marked by slow and steady decrease in lightning frequency. Despite very high flash rate during
the active stage, no severe weather conditions are observed at the ground. It is proposed that the short duration of the active
stage might be the reason for the non-observance of severe weather conditions at the ground. Analysis of Skew-t graph at Guwahati
suggests that vertical distribution of Convective Available Potential Energy (CAPE) also may play some role in non-occurrence
of severe weather at ground in spite of large lightning flash rate and lightning jump observed in this thunderstorm. Further,
all electric field changes after a lightning discharge indicates the presence of strong Lower Positive Charge Centers (LPCC)
in the active and dissipation stages. This suggests that LPCC plays an important role in initiation of lightning discharges
in these stages. 相似文献
3.
Bernd Wunder 《Contributions to Mineralogy and Petrology》1998,132(2):111-120
The water-pressure and temperature stability fields of clinohumite-OH, chondrodite-OH and phase A were determined in reversed
equilibrium experiments up to 100 kbar within the system MgO–SiO2–H2O. Their PT-fields differ from results from former synthesis experiments. Bracketing experiments on the reaction phase A + low P-clinoenstatite ⇆ forsterite + water resulted in a slightly steeper dP/dT-slope compared to earlier experiments for this equilibrium. Clinohumite-OH and chondrodite-OH both have large stability fields
which extend over pressure ranges of more than 80 kbar. However, they are hardly relevant as hydrous minerals within the subducted
oceanic lithosphere. Both are too Mg-rich for a typical mantle bulk composition. In addition, the dehydration of subducted
oceanic lithosphere – due to (forsterite + water)-forming reactions – will occur before the two humite-group phases even become
stable. Restricted to the cool region of cold subducting slabs, phase A, however, might be formed via the reactions phase
A + low P-/high P-clinoenstatite ⇆ forsterite + water or antigorite + brucite ⇆ phase A + water, before dehydration of the oceanic lithosphere
occurs.
Received: 22 July 1997 / Accepted: 12 March 1998 相似文献
4.
G. Diego Gatta Romano Rinaldi K. S. Knight G. Molin G. Artioli 《Physics and Chemistry of Minerals》2007,34(3):185-200
The temperature induced structural evolution and thermoelastic behaviour of a natural (Pbca) orthopyroxene (Opx), with chemical formula M2(Mg0.856Ca0.025Fe2+
0.119) M1(Mg0.957Fe2+
0.011Fe3+
0.016Cr0.011Al0.005)Al0.032Si1.968O6, from a suite of high pressure ultramafic nodules of mantle origin, have been investigated by in-situ neutron powder diffraction
at several temperatures starting from 1,200°C down to 150°C. Unit-cell parameter variations as a function of T show no phase transition within this temperature range. The volume thermal expansion coefficient, α = V
−1(∂V/∂T) P0, varies linearly with T. The axial thermal expansion coefficients, αj = l
j−1(∂l
j/∂T)P0, increase non-linearly with T. The principal Lagrangian unit-strain coefficients (ɛ//a, ɛ//b, ɛ//c), increase continuously with T. However, the orientation of the unit-strain ellipsoid appears to change with T. With decreasing T, the values of the unit-strain coefficients along the b and c axes tend to converge. The orientation at ΔT = 1,080°C is maintained down to the lowest temperature (150°C). The two non-equivalent tetrahedral chains, TA
n
OA3n
and TB
n
OB3n
, are kinked differently. At room-T, the TB
n
OB3n
chain is more strongly kinked by about 23° than the TA
n
OA3n
chain. With increasing T, the difference decreases by 3° for the TB
n
OB3n
chain. The intersite cation exchange reaction between M1 and M2 (Mg2+ and Fe2+) shows a slight residual order at 1,200°C followed by reordering with decreasing temperature although seemingly not with
a definite progressive trend. At the lowest temperature reached (150°C), reordering has occurred with the same value of partitioning
coefficient K
D as that before heating. The absence of the expected phase transition is most likely due to the presence of minor amounts
of Fe3+, Al, Ca and Cr which must play a crucial role on the thermoelastic behaviour and phase stability fields in natural Opx, with
consequent important petrologic and geological implications. 相似文献
5.
Sediment and Lower Water Column Oxygen Consumption in the Seasonally Hypoxic Region of the Louisiana Continental Shelf 总被引:1,自引:0,他引:1
We report integrated measurements of sediment oxygen consumption (SOC) and bottom water plankton community respiration rates
(WR) during eight cruises from 2003 to 2007 on the Louisiana continental shelf (LCS) where hypoxia develops annually. Averaged
by cruise, SOC ranged from 3.9 to 25.8 mmol O2 m−2 day−1, whereas WR ranged from 4.1 to 10.8 mmol O2 m−3 day−1. Total below-pycnocline respiration rates ranged from 46.4 to 104.5 mmol O2 m−2 day−1. In general, below-pycnocline respiration showed low variability over a large geographic and temporal range, and exhibited
no clear spatial or inter-annual patterns. SOC was strongly limited by dissolved oxygen (DO) in the overlying water; whereas,
WR was insensitive to low DO, a relationship that may be useful for parameterizing future models. The component measures,
WR and SOC, were similar to most prior measurements, both from the LCS and from other shallow estuarine and coastal environments.
The contribution of SOC to total below-pycnocline respiration averaged 20 ± 4%, a finding that differs from several prior
LCS studies, but one that was well supported from the broader estuarine and oceanic literature. The data reported here add
substantially to those available for the LCS, thus helping to better understand oxygen dynamics on the LCS. 相似文献
6.
Analysis of monthly momentum transport of zonal waves at 850 hPa for the period 1979 to 1993, between ‡S and ‡N for January
to April, using zonal (u) and meridional (v) components of wind taken from the ECMWF reanalysis field, shows a positive correlation (.1% level of significance) between
the Indian summer monsoon rainfall (June through September) and the momentum transport of wave zero TM(0) over latitudinal
belt between 25‡S and 5‡N (LB) during March. Northward (Southward) TM(0) observed in March over LB subsequently leads to a
good (drought) monsoon season over India which is found to be true even when the year is marked with the El-Nino event. Similarly
a strong westerly zone in the Indian Ocean during March, indicates a good monsoon season for the country, even if the year
is marked with El-Nino. The study thus suggests two predictors, TM(0) over LB and the strength of westerly zone in the Indian
Ocean during March. 相似文献
7.
Link between convection and meridional gradient of sea surface temperature in the Bay of Bengal 总被引:2,自引:0,他引:2
We use daily satellite estimates of sea surface temperature (SST) and rainfall during 1998–2005 to show that onset of convection
over the central Bay of Bengal (88–92°E, 14–18°N) during the core summer monsoon (mid-May to September) is linked to the meridional
gradient of SST in the bay. The SST gradient was computed between two boxes in the northern (88–92°E, 18–22°N) and southern
(82–88°E, 4–8°N) bay; the latter is the area of the cold tongue in the bay linked to the Summer Monsoon Current. Convection
over central bay followed the SST difference between the northern and southern bay (ΔT) exceeding 0.75°C in 28 cases. There was no instance of ΔT exceeding this threshold without a burst in convection. There were, however, five instances of convection occurring without
this SST gradient. Long rainfall events (events lasting more than a week) were associated with an SST event (ΔT ≥ 0.75°C); rainfall events tended to be short when not associated with an SST event. The SST gradient was important for the
onset of convection, but not for its persistence: convection often persisted for several days even after the SST gradient
weakened. The lag between ΔT exceeding 0.75°C and the onset of convection was 0–18 days, but the lag histogram peaked at one week. In 75% of the 28 cases,
convection occurred within a week of ΔT exceeding the threshold of 0.75°C. The northern bay SST, T
N
, contributed more to ΔT, but it was a weaker criterion for convection than the SST gradient. A sensitivity analysis showed that the corresponding
threshold for T
N
was 29°C. We hypothesise that the excess heating (∼1°C above the threshold for deep convection) required in the northern
bay to trigger convection is because this excess in SST is what is required to establish the critical SST gradient. 相似文献
8.
The hydration state of Na- and K-exchanged clinoptilolite from Castle Creek (Idaho, U.S.A.) has been measured by a pressure
titration method to 300 °C and P
H2O<30 bars. The water content of clinoptilolite can be predicted as a function of water activity and temperature with the equation:
a
H2O = [exp[[−ΔH
h
∘/nRT] + [ΔS
h
∘/nR] − 1/nRT· [W1
X
h + W2
X
h
2]− ln(X
a/X
h)]]−1 where T is degrees in Kelvin, ΔH
h
∘ is the standard molal enthalpy of hydration, ΔS
h
∘ is the entropy of hydration, X
h and X
a are, respectively, the mole fractions of the hydrous and anhydrous components of the solid solution, W
1 and W
2 are interaction parameters, n is the maximum number of moles of H2O per formula unit (based on 12 oxygens), and R is the gas constant. This equation can be used to locate clinoptilolite-H2O isohydrons in a
H2O-T space below the liquid-vapor equilibrium curve of water. The standard molal Gibbs free energy of hydration is −47.62 ± 5.52 kJ/mol
H2O and −5.40 ± 2.71 kJ/mol H2O for the Na- and K-clinoptilolite, respectively. These standard-state thermodynamic properties of clinoptilolite hydration
are in good agreement with previous data at low H2O pressures. The experiments indicate that clinoptilolite progressively dehydrates with increasing temperature at pressures
along the liquid-vapor equilibrium curve. Kinetic data above 150 °C show that clinoptilolite dehydration and hydration reactions
are fast and reversible and that steady-state hydration states are attained in minutes.
Received: 19 June 1998 / Revision, accepted 14 December 1998 相似文献
9.
Analysis of fifty four (1951–2004) years of daily energetics of zonal waves derived from NCEP/NCAR wind (u and υ) data and daily rainfall received over the Indian landmass (real time data) during southwest monsoon season (1 June–30 September)
indicate that energetics (momentum transport and kinetic energy) of lower tropospheric ultra-long waves (waves 1 and 2) of
low latitudes hold a key to intra-seasonal variability of monsoon rainfall over India.
Correlation coefficient between climatology of daily (122 days) energetics of ultra-long waves and climatology of daily rainfall
over Indian landmass is 0.9. The relation is not only significant but also has a predictive potential. The normalised plot
of both the series clearly indicates that the response period of rainfall to the energetics is of 5–10 days during the onset
phase and 4–7 days during the withdrawal phase of monsoon over India. During the established phase of monsoon, both the series
move hand-in-hand. Normalised plot of energetics of ultra-long waves and rainfall for individual year do not show marked deviation
with respect to climatology. These results are first of its kind and are useful for the short range forecast of rainfall over
India. 相似文献
10.
T. G. Sitnik 《Astronomy Reports》2010,54(4):317-326
Using the results of our Hα interferometric observations and observational data on the 21 cm and CO lines, we have analyzed the structure and kinematics
of the interstellar medium in the extended vicinity of the star WR 137 and the supernova remnants CTB 87 and G73.9+0.9. A
shell structure with a radius of up to 40′ observable in optical lines has been discovered around WR 137. The high-velocity
motions of ionized hydrogen inside this shell can be interpreted as expansion of the gas swept out by the wind of WR 137 at
velocities of up to 60 km/s. The ionized hydrogen near WR 137 emits at the systematic velocity V
LSR ∼ 6–18 km/s. The expansion ofG73.9+0.9 at a velocity of up to 55 km/s has been confirmed. The systematic velocities of the
ionized hydrogen toward this supernova remnant are V
LSR ≃ −14…+14 km/s. An HI shell around G73.9+0.9 has been detected at velocities V
LSR≃−14…−8 km/s. A very faint optical shell of CTB 87 with a size of about 20′ has also been detected. Evidence that CTB 87 is
located in the Cygnus Arm is presented. 相似文献
11.
A worldwide dataset of organic material from 553 samples belonging to coal and carbonaceous materials was used to analyze
the evolution of hydrogen index (HI) and bitumen index (BI) with increasing thermal maturity. Basic statistical analyses were
applied to detect the boundary lines of HImax and BImax in delineating the upper and lower limits of the HI and BI bands for the majority of samples. In addition, cross-plots of
HI or BI versus maturity (Ro% and T
max) also provide criteria for defining the HImax and BImax boundary lines. The constructed HI and BI bands are broad at low maturities and become narrower with increasing thermal maturities.
The petroleum generation potential is completely exhausted at the vitrinite reflectance of 2.0–2.2% or T
max of 510–520°C. An increase in HI implies extra petroleum generation which was related to changes in structure of organic materials.
A declining BI means that the oil expulsion window starts to occur at the vitrinite reflectance range of 0.75–1.05%. The petroleum
potential can be divided into four different areas based on the cross-plot of HI versus Ro%. The highest petroleum potential
area is located in section II with Ro = 0.6–1.0% and HI > 100. The oil generation potential is rapidly exhausted at section
III with Ro > 1.0%. This result is also in accordance with the result of curve regression of HI versus Ro% based on 80 samples
with Ro = 1.02–3.43% (R
2 = 0.72). Overall, the total oil window can be extended up to Ro = ~1.25–1.95%. Finally, in the cross-plots of S1 versus S2,
shale or C-shale exhibits a higher and slowly decreased slope, compared with a lower and then sharply increased slope of coal
samples, which is attributable to their compositional difference in organic material. 相似文献
12.
J. Zhang 《Physics and Chemistry of Minerals》2000,27(3):145-148
Isobaric volume measurements for MgO were carried out at 2.6, 5.4, and 8.2 GPa in the temperature range 300–1073 K using
a DIA-type, large-volume apparatus in conjunction with synchrotron X-ray powder diffraction. Linear fit of the thermal expansion
data over the experimental pressure range yields the pressure derivative, (∂α/∂P)
T
, of −1.04(8) × 10−6 GPa−1 K−1 and the mean zero-pressure thermal expansion α0,
T
= 4.09(6) × 10−5 K−1. The α0,
T
value is in good agreement with results of Suzuki (1975) and Utsumi et al. (1998) over the same temperature range, whereas
(∂α/∂P)
T
is determined for the first time on MgO by direct measurements. The cross-derivative (∂α2/∂P∂T) cannot be resolved because of large uncertainties associated with the temperature derivative of α at all pressures. The
temperature derivative of the bulk modulus, (∂K
T/∂T)
P
, of −0.025(3) GPa K−1, obtained from the measured (∂α/∂P)
T
value, is in accord with previous findings.
Received: 2 April 1999 / Revised, accepted: 22 June 1999 相似文献
13.
M SHRAVAN KUMAR V K ANANDAN AMIT KESARKAR P NARASIMHA REDDY 《Journal of Earth System Science》2011,120(1):65-72
Doppler SODAR (Sound Detection and Ranging) measurements over a tropical Indian station at National Atmospheric Research Laboratory
(NARL), Gadanki (13.5°N, 79.2°E) during two consecutive monsoon seasons, 2007 and 2008, are investigated to study the influence
of mechanically generated turbulence on temperature structure parameter (CT2)_{\rm T}^{2}) in the convective boundary layer. Increase in the CT2_{\rm T}^{2} is observed after the arrival of monsoon for both seasons. Contribution of vertical wind shear in horizontal wind component
to CT2_{\rm T}^{2} due to zonal winds is responsible for the increase observed in the temperature structure parameter which is inferred from
the results obtained. CT2_{\rm T}^{2} is found to be increased by an order of 2 in both the lower and upper altitudes, respectively. Magnitude of wind speed is
reported to be doubled with the arrival of monsoon. It is also observed that, southwest monsoon wind modulates the day-to-day
variations of wind pattern over this station during the onset phase of monsoon season. The lower variability observed at lower
height is attributed to the complex topography surrounding this region. 相似文献
14.
G. Gruau J. Bernard-Griffiths C. Lécuyer O. Henin J. Macé M. Cannat 《Contributions to Mineralogy and Petrology》1995,121(4):337-350
Peridotites, dykes and gabbros from the 470–420 Ma Trinity Ophiolite Complex of northern California exhibit large geochemical
rare earth element (REE) and Nd isotopic variations on the small scales which are indicative of a complex history. The Trinity
Ophiolite, which covers an area of ≈1600 km2, consists of three distinct units: (1) a ∼2–4 km-thick sheet of plastically deformed peridotites, including various ultrabasic
lithologies (plagioclase and spinel lherzolite, harzburgite, wherlite and dunite); the peridotite unit is a fragment of mantle
lithosphere of oceanic affinity; (2) a series of small (∼1 km diameter) undeformed gabbroic massifs; (3) several generations
of basic dykes. The peridotites display the largest geochemical and isotopic variations, with ɛNd(T) values ranging from +10 down to 0. In the gabbroic massifs and intrusive dykes, the variation in model ɛNd(T) values is reduced to 7 ɛNd units: 0 to +7. As a general rule, peridotites, gabbros and dykes with ɛNd(T) values around 0 or +3 give less depleted L(light)REE patterns than do those with ɛNd(T) values in the range +7 to +10. In the peridotites, the Nd isotopic variations take place over very short distances, with
jumps as large as 7 ɛNd units occurring on scales of less than 20 m. Comparison with available age data indicates that the peridotites with ɛNd(T)≈+10 could be slightly older than the intrusive gabbro massifs and basic dykes (470 Ma vs. 420 Ma). Strontium isotopic data
used in connection with Sm-Nd results demonstrate that the 10 ɛNd units variation displayed by the Trinity Peridotite is a primary feature and not an artefact due to REE mobility during seawater
interaction. The variable Nd isotopic signatures and variable LREE patterns in the Trinity Peridotite cannot represent mantle
source characteristics as there is evidence that this unit was partially melted when it rose as part of the upwelling convecting
mantle. Field, petrographic, geochemical and isotopic data rather suggest that the observed heterogeneity is due to local
reactions between a 470 Ma proto-peridotite with ɛNd(T)=+10 and younger (420 Ma) basaltic melts with lower ɛNd(T) values (i.e. the gabbroic massifs and the dykes). The gabbros and basic dykes of the Trinity Complex have geochemical and
isotopic compositions similar to the arc basalts from the adjacent Copley Formation, so it is proposed that the younger melts
are related to arc magmatism.
Received: 13 January 1995/Accepted 5 May 1995 相似文献
15.
This study presents data on the composition of organic matter from the Late Silurian sediments of the Chernov uplift. These sediments are characterized by low Corg contents, which may reach 1–3% in individual layers. A relatively high thermal maturity of organic matter is confirmed by polycyclic biomarker distributions and Rock-Eval pyrolyisis data. Despite its higher thermal maturity level (T max = 456°C), kerogen in carbonaceous shales from the Padymeityvis River exhibits good preservation of long-chain n-alkyl structures, which are readily identified in the 13C NMR spectra and by the molecular analysis of the kerogen pyrolysis products. 相似文献
16.
Yongsik Sin Bonggil Hyun Quang-Dung Bach Sungryull Yang Chul Park 《Estuaries and Coasts》2012,35(3):839-852
Temporal and spatial variations in phytoplankton in Asan Bay, a temperate estuary under the influence of monsoon, were investigated
over an annual cycle (2004). Phytoplankton blooms started in February (>20 μg chl l−1) and continued until April (>13 μg chl l−1) during the dry season, especially in upstream regions. The percentage contribution of large phytoplankton (micro-sized)
was high (78–95%) during the blooms, and diatoms such as Skeletonema costatum and Thalassiosira spp. were dominant. The precipitation and freshwater discharge from embankments peaked and supplied nutrients into the bay
during the monsoon event, especially in July. Species that favor freshwater, such as Oscillatoria spp. (cyanobacteria), dominated during the monsoon period. The phytoplankton biomass was minimal in this season despite nutrient
concentrations that were relatively sufficient (enriched), and this pattern differed from that in tropical estuaries affected
by monsoon and in temperate estuaries where phytoplankton respond to nutrient inputs during wet seasons. The flushing time
estimated from the salinity was shorter than the doubling time in Asan Bay, which suggests that exports of phytoplankton maximized
by high discharge directly from embankments differentiate this bay from other estuaries in temperate and tropical regions.
This implies that the change in physical properties, especially in the freshwater discharge rates, has mainly been a regulator
of phytoplankton dynamics since the construction of embankments in Asan Bay. 相似文献
17.
Timotej Verbovšek 《Environmental Geology》2008,53(6):1173-1182
Diagenetic effects upon the hydraulic parameters of dolomite aquifers were examined. Results indicate that dolomites affected
only by late (burial) diagenesis are economically more interesting to exploit than those formed first by early and then also
affected by late diagenesis, as the values of most studied hydraulic parameters (transmissivity, specific capacity, linearized
specific capacity and maximum yields) are higher in the former group. Data were collected from the hydrogeological reports
of 298 wells in dolomites from Permian to Cretaceous age in Slovenia, classified in a relational hydrogeological database
and analyzed by statistical methods. The studied parameters are hydraulic conductivity K, transmissivity T, specific capacity q (=Q/s), linearized specific capacity Ql (=q/d) and maximum yields Q
max. Values of the studied parameters are distributed log-normally according to most normality tests and span several orders
of magnitude. Statistical tests show significant differences between the “late” and “early + late” groups for parameters q, Ql and T, and non-significant differences for K and Q
max. 相似文献
18.
R. T. Ratheesh Kumar Tanmay K. Maji Rajesh R. Nair 《Journal of Earth System Science》2010,119(5):717-730
Indian Ocean subduction zone is one of the most active plate margins of the globe as evident from its vast record of great
magnitude earthquake and tsunami events. We use Bouguer admittance (Morlet isostatic response function) in Sumatra-Java subduction
zones comprising both the subduction and over-riding plates to determine the lithospheric mechanical strength variations.
We determine effective elastic thickness (T
e
) for five oceanic windows (size 990 × 990 km2) by analyzing the admittance using Bouguer gravity and bathymetry data. The results show bimodal T
e
values < 20 km for Sumatra and 20−40 km for Java. The lower bimodal values obtained for Sumatra appears to correlate well
with the zones of historical seismicity. This is in sharp contrast with Java subduction zone, which shows higher T
e
values (20–40 km) and apparently associated with low magnitude earthquakes. We suggest a strong and wide interseismic coupling
for Sumatra between the subducting and over-riding plates, and deeper mantle contributing to low strength, shallow focus —
high magnitude seismicity and vice versa for Java, leading to their seismogenic zonation. 相似文献
19.
T. G. Sitnik 《Astronomy Reports》2011,55(7):616-621
The structure and kinematics of the ISM in an extended vicinity of the star WR 139 is analyzed using the results of original
Hα interferometric observations together with radio and infrared data. A CO cavity with a size of up to 40′ has been detected
around the star at velocities of V
LSR ∼ 2.5–10 km/s; the cavity is bounded to the North by a shell radiating in the optical. Ionized hydrogen emits at the systematic
velocities V
LSR ∼ 6–14 km/s toward the CO cavity, and at V
LSR ≃ 4–11 km/s toward the shell. High-velocity motions of ionized hydrogen inside the cavity testify to the probable expansion
of gas that has been swept out by the stellar wind of WR 139 at velocities of up to 60–80 km/s. 相似文献
20.
In this paper, acoustic sounder (sodar) derived vertical velocity variance (σ
w
2
) and inversion height (Z
i) are used to compute the surface heat flux during the convective activity in the morning hours. The surface heat flux computed
by these methods is found to be of the same order of magnitude as that obtained from tower measurements. Inversion heights
derived from sodar reflectivity profiles averaged for an hour are compared with those obtained from the σ
w
2
/Z profile. Variation of σ
w
2
in the mixed layer is discussed. The data were collected during the Monsoon Trough Boundary Layer Experiment 1990 at Kharagpur.
The analysis is made for four days which represent the pre-monsoon, onset, active and relatively weak phases of the summer
monsoon 1990. The interaction of the ABL with the monsoon activity is studied in terms of the variation of inversion height,
vertical velocity variance and surface heat flux as monsoon progresses from June to August. 相似文献