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赤泥处理铅酸蓄电池厂硫酸雾研究

舒月红, 陈杰, 方瑜, 陈红雨

舒月红, 陈杰, 方瑜, 陈红雨. 赤泥处理铅酸蓄电池厂硫酸雾研究[J]. 华南师范大学学报(自然科学版), 2015, 47(1): 55-59. DOI: 10.6054/j.jscnun.2014.12.002
引用本文: 舒月红, 陈杰, 方瑜, 陈红雨. 赤泥处理铅酸蓄电池厂硫酸雾研究[J]. 华南师范大学学报(自然科学版), 2015, 47(1): 55-59. DOI: 10.6054/j.jscnun.2014.12.002
Shu Yuehong, Chen Jie, Fang Yu, Chen Hongyu. Removal of Sulfuric Acid Mist from LeadAcid Battery Plants by Red Mud[J]. Journal of South China Normal University (Natural Science Edition), 2015, 47(1): 55-59. DOI: 10.6054/j.jscnun.2014.12.002
Citation: Shu Yuehong, Chen Jie, Fang Yu, Chen Hongyu. Removal of Sulfuric Acid Mist from LeadAcid Battery Plants by Red Mud[J]. Journal of South China Normal University (Natural Science Edition), 2015, 47(1): 55-59. DOI: 10.6054/j.jscnun.2014.12.002

赤泥处理铅酸蓄电池厂硫酸雾研究

基金项目: 

广东省教育部产学研结合项目(2011B090400560);广州市科技计划项目 (11A92091438)

详细信息
    通讯作者:

    舒月红,副教授,Email:hongershu@163.com.

  • 中图分类号: X511

Removal of Sulfuric Acid Mist from LeadAcid Battery Plants by Red Mud

  • 摘要: 采用固定床动态吸附法研究赤泥对硫酸雾的吸附效果,探讨了赤泥不同煅烧温度、煅烧时间以及填料孔隙率对硫酸雾吸附效果的影响.结果表明,赤泥对硫酸雾具有较好的去除效果.当煅烧温度为750 ℃、煅烧时间为5 h、孔隙率为26%时,赤泥对硫酸雾的去除率最高,能达到95%以上.运用扫描电镜、X射线衍射、比表面积测定等方法分析了赤泥的结构特征和成分组成,证明赤泥具有较好的吸附性能.
    Abstract: In this paper, the dynamic sorption of sulfuric acid mist from leadacid battery plants by red mud was studied. The effect of sintering temperature, sintering time and sorbent porosity of red mud on H_2SO_4 mist removal efficiency was investigated. It was found that the sintered sorbents exhibit higher removal capacity for sulfuric acid mist when compared with that of raw red mud. The removal efficiency of sulfuric acid mist can be higher than 95% with the sintering temperature of 750 ℃, sintering time of 5 h and sorbent porosity of 26%. The physical and chemical properties of sorbents were characterized through scanning electron microscopy and Xray diffraction analyses.
  • 研究流行病的传播规律极为重要[1-3].目前, 许多学者利用数学工具描述动力学模型, 进一步预测流行病传播[4-6].疫苗接种是控制流行病传播的重要手段之一[7-9], 为了研究疫苗接种对流行病动力学行为的影响, LAHROUZ等[8]提出了如下带有疫苗接种的SIRS传染病模型:

    {dS=((1p)bμSβSIφ(I)+γR)dt,dI=((μ+c+α)I+βSIφ(I))dt,dR=(pb(μ+γ)R+αI)dt, (1)

    其中, SIR分别代表易感者、感染者、恢复者的人数;所有参数均非负, 其生物学意义如下:b为出生率, p (0≤p≤1)为疫苗接种率, μ为自然死亡率, c为因病死亡率, β为感染系数, α为恢复率, γ为恢复者免疫力丧失率, φ(I)为正函数, 且φ(0)=1, φ′(I)≥0.该模型给出了无病平衡点和地方病平衡点, 讨论了2个平衡点的全局渐近稳定性.

    在疾病爆发期间, 信息干预(宣传、报道、教育等)会对人们的行为产生影响, 从而影响流行病的传播速度.近年来, 有许多学者研究了信息干预对流行病传播的影响[10-12].文献[6]指出媒体报道虽然不能使感染者恢复, 但可以降低感染者人数的峰值.因此, 将媒体报道因素考虑到模型中是很有必要的.

    本文将信息干预引入到模型(1)中, 得到了新的基于信息干预和疫苗接种的SIRS传染病模型, 研究了新模型平衡点的存在性及其渐近稳定性, 给出了基本再生数, 并通过数值模拟验证了理论结果.

    将信息干预引入到模型(1)中, 得到了新的基于信息干预和疫苗接种的SIRS传染病模型:

    {dS=((1p)bμSβSIφ(I)+γRμ1mZS)dt,dI=((μ+c+α)I+βSIφ(I))dt,dR=(pb(μ+γ)R+αI+μ1mZS)dt,dZ=(aI1+a1Ia0Z)dt, (2)

    其中, Z为信息密度, mμ1aa1a0分别表示信息干预率、信息强度、信息增长率、饱和常数和信息自然消亡率.

    本文的主要结果如下:

    定理1  (ⅰ)如果0 < 1, 则无病平衡点E0是局部渐近稳定的;如果0>1,则E0是不稳定的.

    (ⅱ)模型(2)有1个地方病平衡点E*, 且当0>1并满足A1B1>C1A1(B1C1-A1C1)>C12时, E*是局部渐近稳定的.

    定理2  当0=1时, 模型(2)有1个前向分支.

    定理3  当0 < 1时, 模型(2)的无病平衡点U0=(X0, 0)是全局渐近稳定的.

    定理4  若0>1且

    a2<a03(c+2μβSγφ(I)),
    μ21m2<min{a0γ212μ2S2(c+2μβSγφ(I)),a0αμ2(μ+γ)cb2,8μ2(μ+γ)α3cγZ2,a0γ6S2,2γa20(μ+a1b)29a2b2(c+2μβSγφ(I))},

    则模型(2)的地方病平衡点E*是全局渐近稳定的.

    由文献[13]的方法, 可以得到模型(2)的基本再生数:

    0=β(1p)(μ+γ)+βγp(μ+γ)(μ+c+α). (3)

    下面考虑模型(2)的平衡点的存在性.令模型(2)右端等于零, 即

    {(1p)bμSβSIφ(I)+γRμ1mZS=0,(μ+c+α)I+βSIφ(I)=0,pb(μ+γ)R+αI+μ1mZS=0,aI1+a1Ia0Z=0. (4)

    求解方程组(4), 可得模型(2)存在2个平衡点:(1)无病平衡点E0=(μ(1p)b+γbμ(μ+γ),0,pbμ+γ,0). (2)当0>1时,存在地方病平衡点E*=(S*, I*, R*, Z*), 其中

    S=(μ+c+α)φ(I)β,
    R=1μ+γ[pb+αI+μ1ma(μ+c+α)φ(I)Ia0β(1+a1I)],
    Z=aIa0(1+a1I),

    I*是以下方程的唯一正根:

    H(I)=(1p)b(μ+c+α)φ(I)β(μ+c+α)I+γpbμ+γ+αγIμ+γ+μ1maγ(μ+c+α)φ(I)Ia0β(μ+γ)(1+a1I)=0,

    事实上, 如果0>1, 则H(0)>0, H′(I) < 0, 那么limI→∞ H(I)=-∞, 即0>1当且仅当H(I)=0有唯一的正解.

    接下来讨论模型(2)的正解.由模型(2)可得

    dSdt|S=0=(1p)b+γR0,dIdt|I=00,
    dRdt|R=0=pb+αI+μ1mZS0,dZdt|Z=0=aI1+aI0,

    如果考虑该区域内部, 由模型(2)可知人口总数N=S+I+R满足如下微分方程:

    dNdt=bμNcI.

    所以, dNdtbμN, 即supt→∞Nbμ.因此, bμSIR的上界.根据模型(2)的第4个方程和I的界, 有lim supt→∞Zaba0(μ+a1b).而且, 有以下不变集集合:

    Γ={(S,I,R,Z)R4+:S+I+Rbμ,0Zaba0(μ+a1b),S0,I0,R0,Z0}.

    综上, 在非负集R4+上, 解将保持在Γ中.

    为了方便, 给出了模型(2)的可变矩阵:

    \mathit{\boldsymbol{D}} = \left[ {\begin{array}{*{20}{c}} { - \mu - \frac{{\beta I}}{{\varphi \left( I \right)}} - c}&{ - \frac{{\beta S}}{{\varphi \left( I \right)}}}&\gamma &{ - \frac{{\beta I}}{{\varphi \left( I \right)}}}\\ {\frac{{\beta I}}{{\varphi \left( I \right)}}}&{ - \left( {pq} \right)}&0&0\\ {{\mu _1}mZ}&\alpha &{ - \left( {\mu + \gamma } \right)}&{{\mu _1}mS}\\ 0&{\frac{a}{{{{\left( {1 + {a_1}I} \right)}^2}}}}&0&{ - {a_0}} \end{array}} \right]. (5)

    对地方病平衡点E*, 其特征方程为:

    {\lambda ^4} + {A_1}{\lambda ^3} + {B_1}{\lambda ^2} + {C_1}\lambda + {D_1} = 0,

    其中,

    {A_1} = {a_0} + 2\mu + \gamma + \frac{{\beta {I^*}}}{{\varphi \left( {{I^*}} \right)}} + {\mu _1}m{Z^*},
    \begin{array}{l} {B_1} = {a_0}(\mu + \gamma ) + \left( {\mu + {a_0}} \right)\left( {\mu + \frac{{\beta {I^*}}}{{\varphi \left( {{I^*}} \right)}} + {\mu _1}m{Z^*}} \right) + \\ \;\;\;\;\;\;\;\;\gamma \left( {\mu + \frac{{\beta {I^*}}}{{\varphi \left( {{I^*}} \right)}}} \right) + \frac{{{\beta ^2}{S^*}{I^*}}}{{\varphi {{\left( {{I^*}} \right)}^2}}}, \end{array}
    \begin{array}{*{20}{c}} {{C_1} = \frac{{{\beta ^2}{S^*}{I^*}}}{{\varphi {{\left( {{I^*}} \right)}^2}}}\left( {{a_0} + \mu + \gamma } \right) + \frac{{a\beta {I^*}{\mu _1}m{S^*}}}{{{{\left( {1 + {a_1}{I^*}} \right)}^2}}} - \frac{{\beta {I^*}}}{{\varphi \left( {{I^*}} \right)}}\alpha {\gamma ^ + }}\\ {{a_0}\mu \left( {\mu + \frac{{\beta {I^*}}}{{\varphi \left( {{I^*}} \right)}} + {\mu _1}m{Z^*}} \right) + {a_0}\gamma \left( {\mu + \frac{{\beta {I^*}}}{{\varphi \left( {{I^*}} \right)}}} \right),} \end{array}
    \begin{array}{*{20}{c}} {{D_1} = \frac{{{a_0}\beta {I^*}}}{{\varphi \left( {{I^*}} \right)}}(\mu (\mu + c + \alpha ) + \gamma (\mu + c)) + }\\ {\frac{{a\beta {I^*}}}{{\varphi \left( {{I^*}} \right){{\left( {1 + {a_1}{I^*}} \right)}^2}}}\mu {\mu _1}m{S^*}.} \end{array}

    定理1的证明  (ⅰ)与文献[13]中定理2的证明类似, 此处略.

    (ⅱ)显然A1>0, D1>0.由Routh-Hurwitz判据, 若A1B1>C1A1(B1C1-A1D1)>C12, 则JE*的特征方程的所有根要么非负, 要么有负实部.因此, 如果0>1, A1B1>C1, A1(B1C1-A1D1)>C12,则由Hartman-Grobman定理[14]可知E*是局部渐近稳定的.

    定理2的证明  当0=1时, 令x1=S, x2=I, x3=R, x4=Z, 将φ=β作为分叉参数.于是, 对φ=φ*=β*, 由0=1可得\beta^{*}=\frac{b((1-p) \mu+\gamma)}{\mu(\mu+\gamma)(\mu+c+\alpha)} .应用新的变换, 模型(2)可以改写为:

    \left\{ \begin{array}{l} \frac{{{\rm{d}}{x_1}}}{{{\rm{d}}t}} = \left( {1 - p} \right)b - \mu {x_1} - \frac{{\beta {x_1}{x_2}}}{{\varphi \left( {{x_2}} \right)}} + \gamma {x_3} - {\mu _1}m{x_1}{x_4}: = {f_1},\\ \frac{{{\rm{d}}{x_2}}}{{{\rm{d}}t}} = - (\mu + c + \alpha ){x_2} + \frac{{\beta {x_1}{x_2}}}{{\varphi \left( {{x_2}} \right)}}: = {f_2},\\ \frac{{{\rm{d}}{x_3}}}{{{\rm{d}}t}} = pb - (\mu + \gamma ){x_3} + \alpha {x_2} + {\mu _1}m{x_1}{x_4}: = {f_3},\\ \frac{{{\rm{d}}{x_4}}}{{{\rm{d}}t}} = \frac{{a{x_2}}}{{1 + {a_1}{x_2}}} - {a_0}{x_4}: = {f_4}. \end{array} \right.

    对于无病平衡点x*, 可以得到(x*, β*)的雅可比矩阵:

    \begin{array}{l} {\mathit{\boldsymbol{D}}_{{x^ * }}}\left( {{\beta ^ * }} \right) = \\ \left[ {\begin{array}{*{20}{c}} { - \mu }&{ - \left( {\mu + c + \alpha } \right)}&\gamma &{\frac{{ - {\mu _1}m\left[ {\left( {1 - p} \right)\left( {\mu + \gamma } \right) + \gamma p} \right]}}{{\varphi \left( {x_2^*} \right)\left( {\mu + \gamma } \right)}}}\\ 0&0&0&0\\ 0&\alpha &{ - \left( {\mu + \gamma } \right)}&{\frac{{{\mu _1}m\left[ {\left( {1 - p} \right)\left( {\mu + \gamma } \right) + \gamma p} \right]}}{{\varphi \left( {x_2^*} \right)\left( {\mu + \gamma } \right)}}}\\ 0&a&0&{ - {a_0}} \end{array}} \right]. \end{array}

    0=1时, Dx*(β*)有1个零特征值, 且其他特征值都是非负的. Dx*(β*)相应于零特征值的右特征向量为y=(y1, y2, y3, y4)′,其中

    \left\{ \begin{array}{l} {y_1} = \frac{1}{\mu }\left\{ {\frac{{\gamma \alpha }}{{\left( {\mu + \gamma } \right)a}} - \frac{{\mu + c + \alpha }}{a} - \frac{{\mu {\mu _1}m[(1 - p)(\mu + \gamma ) + \gamma p]}}{{\varphi \left( {x_2^*} \right){a_0}{{(\mu + \gamma )}^2}}}} \right\},\\ {y_2} = \frac{1}{a},\\ {y_3} = \frac{1}{{(\mu + \gamma )}}\left\{ {\frac{\alpha }{a} + \frac{{{\mu _1}m[(1 - p)(\mu + \gamma ) + \gamma p]}}{{{a_0}\varphi \left( {x_2^*} \right)(\mu + \gamma )}}} \right\},\\ {y_4} = \frac{1}{{{a_0}}}. \end{array} \right.

    类似地, 可以得到Dx*(β*)相应于零特征值的左特征向量为z=(z1, z2, z3, z4), 其中z1=0, z2=1, z3=0, z4=0.由文献[12]可知,当0=1时, 常数a2b2可决定无病平衡点的稳定性.下面计算a2b2. f=(f1, f2, f3, f4)在(x*, β*)处的非零二阶偏导为:

    \frac{{{\partial ^2}{f_2}}}{{\partial {x_2}\partial {x_1}}} = {\beta ^*},\frac{{{\partial ^2}{f_2}}}{{\partial {x_1}\partial {x_2}}} = {\beta ^*},\frac{{{\partial ^2}{f_2}}}{{\partial {x_2}\partial \beta }} = x_1^*,

    \begin{array}{l} {a_2} = \frac{{ - 2((1 - p)(\mu + \gamma ) + \gamma p)}}{{{a_0}{a^2}\mu {{(\mu + \gamma )}^3}(\mu + c + \alpha )\varphi \left( {x_2^*} \right)}}\left\{ {{a_0}\varphi \left( {x_2^*} \right) \times } \right.\\ \;\;\;\;\;\;\;(\mu + c + \alpha )(\mu + \gamma ) + {a_0}\varphi \left( {x_2^*} \right)\gamma (\mu + c)(\mu + \gamma ) + \\ \;\;\;\;\;\;\;\left. {a\mu {\mu _1}m[(1 - p)(\mu + \gamma ) + \gamma p]} \right\}, \end{array}
    {b_2} = \frac{{(\mu + \gamma )(1 - p) + \gamma p}}{{a\varphi \left( {x_2^*} \right)(\mu + \gamma )}}.

    显然, a2 < 0, b2>0.得证.

    假设模型(2)可改写为[15]:

    \frac{{{\rm{d}}\mathit{\boldsymbol{X}}}}{{{\rm{d}}t}} = F(\mathit{\boldsymbol{X}},Y),\frac{{{\rm{d}}Y}}{{{\rm{d}}t}} = G(\mathit{\boldsymbol{X}},Y),G(\mathit{\boldsymbol{X}},0) = 0,

    其中, \boldsymbol{X} \in \mathbb{R}^{3} Y \in \mathbb{R} 分别代表未感染者和感染者的人数.令U0=(X0, 0)为无病平衡点.

    引理1[15]  若0 < 1且以下条件满足:

    (ⅰ)对\frac{\mathrm{d} \boldsymbol{X}}{\mathrm{d} t}=F(\boldsymbol{X}, 0), \boldsymbol{X}_{0} 是全局渐近稳定的;

    (ⅱ)∀(X, Y)∈Γ, 有G(X, Y)=DYG(X0, 0)Y- \hat{G}(\boldsymbol{X}, Y), \hat{G}(\boldsymbol{X}, Y) \geqslant 0, 其中, DYG(X0, 0)为M-矩阵, 则模型(2)的无病平衡点U0=(X0, 0)是全局渐近稳定的.

    定理3的证明  类似文献[12]中定理2的证明, 有

    \begin{array}{l} F(\mathit{\boldsymbol{X}},Y) = \left( {(1 - p)b - \mu S - \frac{{\beta SI}}{{\varphi (I)}} + \gamma R - {\mu _1}mZS,} \right.\\ \left. {pb - (\mu + \gamma )R + \alpha I + {\mu _1}mZS,\frac{{aI}}{{1 + {a_1}I}} - {a_0}Z} \right), \end{array}
    G(\mathit{\boldsymbol{X}},Y) = - (\mu + c + \alpha )I + \frac{{\beta SI}}{{\varphi (I)}},G(\mathit{\boldsymbol{X}},0) = 0,

    其中, X=(S, R, Z)′, Y=I.无病平衡点U0=E1=(X0, 0)且 \boldsymbol{X}_{0}=\left(\frac{\mu(1-p) b+\gamma b}{\mu(\mu+\gamma)}, \frac{p b}{\mu+\gamma}, 0\right).取t→∞, 则有 \boldsymbol{X} \rightarrow\left(\frac{\mu(1-p) b+\gamma b}{\mu(\mu+\gamma)}, \frac{p b}{\mu+\gamma}, 0\right).显然X0是全局渐近稳定的.更进一步地,

    \begin{array}{l} G(\mathit{\boldsymbol{X}},Y) = - (\mu + c + \alpha )\left( {1 - {\Re _0}} \right)I - \\ \;\;\;\;\;\;\;\frac{{\beta I}}{{\varphi (I)}}\left[ {\frac{{\varphi (I)(\mu (1 - p)b + \gamma b)}}{{\mu (\mu + \gamma )}} - S} \right]. \end{array}

    S \leqslant \frac{\mu(1-p) b+\gamma b}{\mu(\mu+\gamma)}, 则

    \hat G(\mathit{\boldsymbol{X}},Y) = \frac{{\beta I}}{{\varphi (I)}}\left[ {\frac{{\varphi (I)(\mu (1 - p)b + \gamma b)}}{{\mu (\mu + \gamma )}} - S} \right] \ge 0.

    所以条件(ⅰ)、(ⅱ)满足.因此, 当0 < 1时, 模型(2)的无病平衡点是全局渐近稳定的.

    定理4的证明  在区间Γ上, 考虑函数V:

    \begin{array}{l} V(S,I,R,Z) = \frac{1}{2}{\left[ {\left( {S - {S^*}} \right) + \left( {I - {I^*}} \right) + \left( {R - {R^*}} \right)} \right]^2} + \\ \;\;\;\;{m_1}\left( {I - {I^*} - {I^*}\log \frac{I}{{{I^*}}}} \right) + \frac{{{m_2}}}{2}{\left( {S - {S^*} + I - {I^*}} \right)^2} + \frac{{{m_3}}}{2}{\left( {R - {R^*}} \right)^2} + \\ \;\;\;\;\frac{1}{2}{\left( {Z - {Z^*}} \right)^2} = {V_1} + {m_1}{V_2} + {m_2}{V_3} + {m_3}{V_4} + {V_5}, \end{array} (6)

    其中,m1m2m3都是正常数.可以得到Vi(i=1, 2, …, 5)的导数如下:

    \begin{array}{l} {{\dot V}_1} = - \mu {\left( {S - {S^*}} \right)^2} - (\mu + c){\left( {I - {I^*}} \right)^2} - \mu {\left( {R - {R^*}} \right)^2} - \\ \;\;\;\;\;\;(2\mu + c)\left( {S - {S^*}} \right)\left( {I - {I^*}} \right) - 2\mu \left( {S - {S^*}} \right)\left( {R - {R^*}} \right) - \\ \;\;\;\;\;\;(2\mu + c)\left( {I - {I^*}} \right)\left( {R - {R^*}} \right), \end{array}
    \begin{array}{l} {{\dot V}_2} = - \frac{{\beta S}}{{\varphi (I)\varphi \left( {{I^*}} \right)}}\left( {\varphi (I) - \varphi \left( {{I^*}} \right)} \right)\left( {I - {I^*}} \right) + \\ \;\;\;\;\;\;\;\frac{\beta }{{\varphi \left( {{I^*}} \right)}}\left( {S - {S^*}} \right)\left( {I - {I^*}} \right), \end{array}
    \begin{array}{l} {{\dot V}_3} = - \mu {\left( {S - {S^*}} \right)^2} - \frac{{\beta {S^*}}}{{\varphi \left( {{I^*}} \right)}}{\left( {I - {I^*}} \right)^2} + \gamma \left( {S - {S^*}} \right)\left( {R - {R^*}} \right) - \\ \;\;\;\;\;{\mu _1}m{S^*}\left( {S - {S^*}} \right)\left( {Z - {Z^*}} \right) - {\mu _1}mZ{\left( {S - {S^*}} \right)^2} - \\ \;\;\;\;\;\left( {\mu + \frac{{\beta {S^*}}}{{\varphi \left( {{I^*}} \right)}}} \right)\left( {S - {S^*}} \right)\left( {I - {I^*}} \right) + \gamma \left( {I - {I^*}} \right)\left( {R - {R^*}} \right) - \\ \;\;\;\;\;{\mu _1}mZ\left( {I - {I^*}} \right)\left( {S - {S^*}} \right) - {\mu _1}m{S^*}\left( {I - {I^*}} \right)\left( {Z - {Z^*}} \right), \end{array}
    \begin{array}{l} {{\dot V}_4} = - (\mu + \gamma ){\left( {R - {R^*}} \right)^2} + \alpha \left( {R - {R^*}} \right)\left( {I - {I^*}} \right) + \\ \;\;\;\;\;{\mu _1}m{Z^*}\left( {R - {R^*}} \right)\left( {S - {S^*}} \right) + {\mu _1}mS\left( {R - {R^*}} \right)\left( {Z - {Z^*}} \right), \end{array}
    {{\dot V}_5} = \frac{{a\left( {I - {I^*}} \right)\left( {Z - {Z^*}} \right)}}{{\left( {1 + {a_1}I} \right)\left( {1 + {a_1}{I^*}} \right)}} - {a_0}{\left( {Z - {Z^*}} \right)^2}.

    m_{1}=\frac{\varphi\left(I^{*}\right)}{\beta}\left((2 \mu+c)+\frac{2 \mu}{\gamma}\left(\mu+\frac{\beta S^{*}}{\varphi\left(I^{*}\right)}\right)\right) , m_{2}=\frac{2 \mu}{\gamma}, m_{3}=\frac{c}{\alpha}, 可得到:

    \begin{array}{l} \dot V \le - \mu {\left( {S - {S^*}} \right)^2} - \left( {\mu + c} \right){\left( {I - {I^*}} \right)^2} - \mu {\left( {R - {R^*}} \right)^2} - \\ \;\;\;\;\;\frac{{2\mu }}{\gamma }\left( {\mu {{\left( {S - {S^*}} \right)}^2} + \frac{{\beta {S^*}}}{{\varphi \left( {{I^*}} \right)}}{{\left( {I - {I^*}} \right)}^2} + {\mu _1}mZ{{\left( {S - {S^*}} \right)}^2}} \right) - \\ \;\;\;\;\;\frac{{2\mu }}{\gamma }\left( {{\mu _1}m{S^*}\left( {S - {S^*}} \right)\left( {Z - {Z^*}} \right) + {\mu _1}mZ\left( {I - {I^*}} \right)\left( {S - {S^*}} \right) + } \right.\\ \;\;\;\;\;\left. {{\mu _1}m{S^*}\left( {I - {I^*}} \right)\left( {Z - {Z^*}} \right)} \right) - \frac{c}{\alpha }\left( {\mu + \gamma } \right){\left( {R - {R^*}} \right)^2} + \\ \;\;\;\;\;\frac{c}{\alpha }\left( {{\mu _1}m{Z^*}\left( {R - {R^*}} \right)\left( {S - {S^*}} \right) + {\mu _1}mS\left( {R - {R^*}} \right)\left( {Z - {Z^*}} \right)} \right) + \\ \;\;\;\;\;\frac{{a\left( {I - {I^*}} \right)\left( {Z - {Z^*}} \right)}}{{\left( {1 + {a_1}I} \right)\left( {1 + {a_1}{I^*}} \right)}} - {a_0}{\left( {Z - {Z^*}} \right)^2}. \end{array}

    在区间Γ上, 取SZ的上界, 若满足

    {a^2} < \frac{{{a_0}}}{3}\left( {c + \frac{{2\mu \beta {S^*}}}{{\gamma \varphi \left( {{I^*}} \right)}}} \right),
    \begin{array}{l} \mu _1^2{m^2} < \min \left\{ {\frac{{{a_0}{\gamma ^2}}}{{12{\mu ^2}{S^{*2}}}}\left( {c + \frac{{2\mu \beta {S^*}}}{{\gamma \varphi \left( {{I^*}} \right)}}} \right),\frac{{{a_0}\alpha {\mu ^2}(\mu + \gamma )}}{{c{b^2}}},} \right.\\ \;\;\;\left. {\frac{{8{\mu ^2}(\mu + \gamma )\alpha }}{{3c\gamma {Z^{*2}}}},\frac{{{a_0}\gamma }}{{6{S^{*2}}}},\frac{{2\gamma a_0^2{{\left( {\mu + {a_1}b} \right)}^2}}}{{9{a^2}{b^2}}}\left( {c + \frac{{2\mu \beta {S^*}}}{{\gamma \varphi \left( {{I^*}} \right)}}} \right)} \right\}, \end{array}

    易得LV≤0.因此, 可知在Γ区间, 如果S=S*, I=I*, R=R*, Z=Z*, 则有LV < 0或LV=0.最后, 由LaSalle不变原理可知E*Γ区间是全局渐近稳定的.

    本节将通过一系列的数值例子来验证模型(2)的无病平衡点和地方病平衡点的稳定性.

    例1  模型(2)的参数取值如下:

    p=0.5, b=1, β=0.01, μ=0.01, μ1=0.01, m=0.017, c=0.005, γ=0.001, α=0.8, a=0.01, a0=0.045, a1=1.令φ(I)=1+I2, 可得0=0.669 3 < 1, E0=(54.545 5, 0, 45.454 5, 0)且E*不存在.显然, 图 1A验证了定理3.

    图  1  模型(2)中疾病的灭绝性分析
    Figure  1.  The extinction analysis of disease for model (2)

    此外, 给出了信息强度μ1对传染病的影响.对于模型(2), 给出了关于I(t)的不同参数μ1(μ1=0, μ1=0.10, μ1=0.20)的时间序列(图 1B).可知在疾病爆发期间, 若增加信息强度μ1, 则可以减少感染者的数量并加速疾病的灭绝.

    例2  模型(2)的参数取值如下:

    p=0.5, b=4, β=0.04, μ=0.02, μ1=0.009, m=0.01, c=0.005, γ=0.01, α=0.7, a=0.02, a0=0.045, a1=1.令φ(I)=1+I2, 可知0=3.174 6>1, a2=4.000 0×10-4 < 0.033 1, μ12m2=8.100 00×10-9 < min{6.634 0×10-7, 1.771 9×10-5, 13.889 7, 2.701 6×10-8, 0.050 5}且E0=(93.333 3, 0, 40.000 0, 0), E*=(74.512 9, 1.238 7, 57.371 4, 0.245 9).显然, 图 2A验证了定理4.

    图  2  模型(2)中疾病的持久性分析
    Figure  2.  The persistence analysis of disease for model (2)

    类似地, 给出了在不同的信息强度μ1(μ1=0, μ1=0.10, μ1=0.20)的时间序列I(t)(图 2B).可知若增加信息强度μ1, 则可降低感染者数量.

    本文研究了基于信息干预和疫苗接种的SIRS传染病模型(2), 分析了该模型中无病平衡点和地方病平衡点的局部、全局稳定性.研究结果表明:

    (1) 通过疫苗接种率0, 可以进一步知道疫苗接种如何影响疾病传播.事实上, 0可以被写成如下形式:

    {\Re _0} = - p\frac{{\beta \mu }}{{(\mu + \gamma )(\mu + c + \alpha )}} + \frac{\beta }{{\mu + c + \alpha }}.

    如果增加疫苗接种率p, 则基本再生数0将会减少.换言之, 疫苗接种率的增加可以抑制疾病的传播.

    (2) 疾病爆发时, 信息强度的增加可以降低感染者的数量并且加速疾病的灭亡.

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出版历程
  • 收稿日期:  2014-02-25
  • 刊出日期:  2015-03-19

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